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1
EC135 Classic 
B1 
Training Manual
Intro – 1Iss. August 2018For instruction only
Intro – Introduction
EC135 Classic
Training Manual
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2
EC135 Classic 
B1 
Training Manual
Intro – 2Iss. August 2018For instruction only
Intro – Introduction
Introduction
Foreword
Welcome to the Airbus EC135 Classic Training Course.This course 
was designed to train pilots and maintenance personnel on the EC135 
helicopter.
The training manual consists of several modules and takes into 
consideration most of ATA 104 specifications. It correlates to the 
sequence of the theoretical training you will receive.
Annotation to the Training Manual
This training manual is not a subject for revision service. It is the 
manufacturer’s practice to continuously improve its products and 
therefore the right is reserved to make without notice alterations in 
design or manufacture which may be deemed necessary.
© All rights reserved.
Reproduction or translation in whole or in part of the contents of this 
publication without permission of Airbus Helicopters Deutschland 
GmbH is not authorized.
Edition 2................................................................................ July 2006
Revision 1 ..................................................................... February 2011
Revision 2 ......................................................................... March 2014
Revision 3 ............................................................................June 2014
Revision 4 ............................................................................. July 2015
Revision 5 .......................................................................October 2015
Revision 6 ........................................................................ August 2018
Airbus Helicopters Deutschland GmbH
Training Academy
P.O. Box 1353
D-86603 Donauwörth
Phone: (0049) 906 71-4481
Fax: (0049) 906 71-4499
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3
EC135 Classic 
B1 
Training Manual
Intro – 3Iss. August 2018For instruction only
Intro – Introduction
Modules
01..........................................General Information
02..........................................Lifting System
03..........................................Fuselage
04..........................................Tail Unit
05..........................................Flight Control
06..........................................Landing Gear
07..........................................Power Plant
08..........................................Standard Equipment
09..........................................Optional Equipment
10..........................................Electrical System
11 .......................................... Inspections
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4
EC135 Classic 
B1 
Training Manual
Intro – 4Iss. August 2018For instruction only
Intro – Introduction
Abbreviations
A
A ...........................................Ampere
AC.........................................Alternating Current
ACK ......................................Acknowledgement
ACP ......................................Audio Control Panel
ADC ......................................Air Data Computer
ADF ......................................Automatic Direction Finder
AEO ......................................All Engines Operative
AFCS ....................................Automatic Flight Control System; 
complete Autopilot system consists 
of APM, AP SAS, Actuator, Sensors, 
Y FOG, P FOG, etc.
AHD ......................................Airbus Helicopters Deutschland
AHRS....................................Attitude and Heading Reference System
ALT.A ....................................Altitude Acquire Mode
AM ........................................Amplitude Modulation
AMM .....................................Aircraft Maintenance Manual
AMU ......................................Audio Management Unit
AP .........................................Autopilot System
APM ......................................Autopilot Module
APMS ...................................Autopilot Mode Selector
AR.........................................Autorotation
ARINC ..................................Digital Bus (Aeronautical Radio 
Incorporated)
ARIS .....................................Anti Resonance Isolation System
ASB ......................................Alert Service Bulletin
ATA .......................................Air Transport Association
ATC .......................................Air Traffic Control
ATT .......................................Attitude
A.TRIM .................................Autopilot Automatic Trim; Attitude Hold 
Function provided by APM as default
AVM ......................................Avionic Manual
B
BAT .......................................Battery
BAT MSTR ............................Battery Master
BFO ......................................Beat Frequency Oscillator
BIT ........................................Built In Test
BL .........................................Buttock Line
BMB ......................................Battery Master Box
BRG ......................................Bearing
BRT ......................................Brightness Key
BTC ......................................Bus Tie Connector
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Intro – Introduction EC135 Classic 
B1 
Training Manual
Intro – 5Iss. August 2018For instruction only
C
CAD ......................................Caution and Advisory Display
CBIT .....................................Continuous Built IN Test
CDI .......................................Course Deviation Indicator
CDS ......................................Cockpit Display System
CDU ......................................Control Display Unit
CECG ...................................Corrosion Erosion Control Guide
CG ........................................Center of Gravity
CLP .......................................Collective Lever Position
CMA ......................................Canadian Marconi NMS Equipment 
(CMA 3000, CMA 9000, etc.)
CMM .....................................Components Maintenance Manual
CMP ......................................Continous Maintenance Program
COM .....................................Communication System
CONT ...................................Control
CPDS....................................Central Panel Display System
CRS ......................................Course
CT .........................................Continuity Test
D
DACS....................................Digital Audio Control System
DC ........................................Direct Current
DCPL ....................................De-Couple
DCU ......................................Data Collection Unit
DDM .....................................Difference in Depth of Modulation
DH ........................................Decision Height
DISCH ..................................Discharge
DME ......................................Distance Measuring Equipment
DP .........................................Dual Pilot
DPIFR ...................................Dual Pilot Instrument Flight Rules
DST ......................................Distance to go
E
EASB ....................................Emergency Alert Service Bulletin
EC.........................................Eurocopter
EEC ......................................Electronic Engine Control (PW)
EECU....................................Electronic Control Unit (TM)
EFIS......................................Electronic Flight Instrument System
e.g.........................................For Example (exempli gratia)
EGT ......................................ExhaustGas Temperature
EHA ......................................Electro-Hydraulic Actuator
ELT .......................................Emergency Locator Transmitter
EMB ......................................Electrical Master Box
ENG ......................................Engine
EPC ......................................Engine Power Check
EPU ......................................External Power Unit
ERR ......................................E-RepaiR
ESS ......................................Essential
ESS BUS ..............................Essential Bus
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Intro – Introduction EC135 Classic 
B1 
Training Manual
Intro – 6Iss. August 2018For instruction only
F
FAA .......................................Federal Aviation Administration
FADEC..................................Full Authority Digital Engine Control
FCDM ...................................Flight Control Display Module
FCDS ....................................Flight Control Dsplay System
fh...........................................Flight Hours
FLIR ......................................Forward Looking Infrared
FLI ........................................First Limit Indication
FLM ......................................Flight Manual
FMCW ..................................Frequency Modulated Continuous Wave
FMM .....................................Fuel Management Module (PW)
FMU ......................................Fuel Metering Unit (TM)
FOG ......................................Fibre Optic Gyros
FRP ......................................Fibre Reinforced Plastic
FS .........................................Fuselage Station
ft............................................Foot (feet)
FWD .....................................Forward
G
GA.........................................Go Around
GBS ......................................Ground Base Software
GCUB ...................................Generator Control Unit Board
GEN ......................................Generator
GLC ......................................Generator Line Contactor
GNS ......................................Garmin single unit COM, NAV & GPS 
equipment (GNS 430, GNS 530 etc.)
GPS ......................................Global Positioning System
GRP ......................................Glassfiber Reinforced Plastic
GS ........................................Glide Slope
GSM .....................................Global System for Mobile Communication
GTN ......................................Garmin Single Unit COM, NAV and GPS 
Equipment (GTN 750)
H
h............................................Hours of time
H/C .......................................Helicopter
HDG ......................................Heading
HIGE .....................................Hover In Ground Effect
HLC ......................................High Load Contactor
HPC ......................................High Power Contactor
HSI........................................Horizontal Situation Indicator
HTG ......................................Heating
HYD ......................................Hydraulic
I
IAS ........................................ Indicated Air Speed
IBF ........................................ Inlet Barrier Filter
IBIT ....................................... Initialized Built In Test
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Intro – Introduction EC135 Classic 
B1 
Training Manual
Intro – 7Iss. August 2018For instruction only
IC .......................................... Intercommunication
ICP ........................................ Instrument Control Panel
ICS........................................ Intercom System
i.e. .........................................That is (id est)
IFR ........................................ Instrument Flight Rules
IGN ....................................... Ignition
ILS ........................................ Instrument Landing System (incl. 
LOC&GS)
IM .......................................... Inner Marker
IN .......................................... Information Notice
INSTR ................................... Instrument
INV........................................ Inverter
IPC........................................ Illustrated Parts Catalog
IPS ........................................ Inches per Second
K
kg ..........................................Kilogram
KIAS .....................................Knots Indicated Air Speed
km .........................................Kilometer
kts .........................................Knots
kW ........................................Kilowatt
L
l. ............................................ liter
lb ...........................................Pound
LBA .......................................Luftfahrt-Bundesamt
LDG ......................................Landing
LED.......................................Light Emitting Diode
LH .........................................Left Hand Side
LOAP ....................................List of Applicable Publications
LOC ......................................Localizer
LOEP ....................................List of Effective Pages
LRU ......................................Line Replaceable Unit
LVDT .....................................Linear Voltage Differential Transducer
LWC ......................................Liquid Water Content
M
m ...........................................Meter
MAN ......................................Manual Mode
max. ......................................Maximum
MB ........................................Magnetic Bearing
MBB ......................................Messerschmitt-Bölkow-Blohm
MCP ......................................Maximum Continous Power
MCP ......................................Multifunctional Control Panel
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Intro – Introduction EC135 Classic 
B1 
Training Manual
Intro – 8Iss. August 2018For instruction only
MGB .....................................Main Gearbox
MGT ......................................Measured Gas Temperature
MHA ......................................Mechano-Hydraulic Actuator
MIKE .....................................Microphone
MIL ........................................Military Standard, Military Specification
min. .......................................Minimum
MISC .....................................Miscellaneous
MM ........................................Mast Moment
MM ........................................Middle Marker
mm ........................................Millimeter
MMEL ...................................Master Minimum Equipment List
MN ........................................Magnetic North
MSM .....................................Master Servicing Manual
MSTR ...................................Master
MTC ......................................Manuel Technique Courant (Standard 
Practices Manual)
MTOM ...................................Maximum Take-Off Mass
N
N1 .........................................Gas Generator Speed
N2 .........................................Power Turbine Speed
NACA ....................................National Advisory Committee for 
Aeronautics
NAV ......................................Navigation System
ND ........................................Navigation Display
NDB ......................................Non Directional Beacon
NMS ......................................Navigation Management System
NORM ...................................Normal Mode of Operation
O
OAT ......................................Outside Air Temperature
OEI .......................................One Engine Inoperative
OVHT ....................................Overheat
OVSP ....................................Overspeed
P
PA .........................................Pressure Altitude
PA .........................................ParallelActuator
PAX .......................................Passenger
PBIT ......................................Power Up Built In Test
PCL .......................................Pilot Check List
PELICAN ..............................Packing Equipment Line for Integrated 
Concept of Avionique Nouvelle
PFD ......................................Primary Flight Display
PIO .......................................Pilot Induced Oscillation
PLB .......................................Prediction Logic Board
PMA ......................................Permanent Magnet Alternator
P/N........................................Part Number
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Intro – Introduction EC135 Classic 
B1 
Training Manual
Intro – 9Iss. August 2018For instruction only
PTT .......................................Press to Talk
PW ........................................Pratt&Whitney
PWR .....................................Power
Q
QDM .....................................Question for Direction, Magnetic 
Heading
QDR ......................................Question for Direction, Magnetic 
Heading ± 180°
QTY ......................................Quantity
R
RA .........................................Radar Altimeter
RCC ......................................Remote Charge Converter
RCU ......................................Reconfiguration Unit
RCP ......................................Remote Control Panel
RD ........................................Reference Datum
REL .......................................Relay
rev.........................................Revolution
RH ........................................Right Hand Side
RMI .......................................Radio Magnetic Indicator
RPM ......................................Revolutions Per Minute
RVDT ....................................Rotary Variable Differential Transducer
S
SAS ......................................Stability Augmentation System (digital); 
SAS functionality used as backup for 
autopilot, provided by YAW SAS, P&R 
SAS. It is a hands on operation.
SAS ......................................Sun Angle Shaded
SB .........................................Service Bulletin
SBAS ....................................Satellite Based Augumentation System
SBC ......................................Shedding Bus Connector
SDS ......................................System Description Section
SEMA....................................Smart Electro-Mechanical Actuator
SHED....................................Shedding
SI .......................................... International System of Units
SIN........................................Safety Information Notice
SN.........................................Serial Number
S/N........................................Serial Number
SMD ......................................Smart Multifunction Display
SN.........................................Serial Number
S/N........................................Serial Number
SQUAWK ..............................Reply to Interrogation Signal (XPD)
SP .........................................Single Pilot
SPD ......................................Speed
SPIFR ...................................Single Pilot Instrument Flight Rules
SPU ......................................Signal Processing Unit
SRD ......................................Status Revision Document
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Intro – Introduction EC135 Classic 
B1 
Training Manual
Intro – 10Iss. August 2018For instruction only
SRM ......................................Structural Repair Manual
SSR ......................................Secondary Surveillance Radar
STBY ....................................Standby
SW ........................................Switch
SW ........................................Software
SYS ......................................System
T
T1 .........................................Engine Temperature at station 1
TCAS ....................................Traffic Alert and Collision Avoidance 
System
TEMP ....................................Temperature
TIP ........................................Technical Improvement Proposal
TM ........................................Turbomeca
TOT ......................................Turbine Outlet Temperature
TQ .........................................Torque
TSN ......................................Time Since New
TST .......................................Test
TTG ......................................Time to Go
TRQ ......................................Torque
TST .......................................Test
TTG ......................................Time To Go
TX .........................................Transceiver
U
UL .........................................Upper Limit
USB ......................................Universal Serial Bus
V
VDC ......................................Voltage - Direct Current
VEH ......................................Vehicle
VEMD ...................................Vehicle and Engine Monitoring Display
VENT ....................................Ventilation
VFR ......................................Visual Flight Rules
VHF ......................................Very High Frequency
VLOC ....................................VOR Localizer
VNE ......................................Never Exceed Speed
VOL ......................................Volume
VOR ......................................Very High Frequency Omnidirectional 
Radio Ranging
VORTAC ...............................VHF Omnidirectional Range Tactical Air 
Navigation System
VOX ......................................Voice Operated Transmission
VS .........................................Vertical Speed
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Intro – Introduction EC135 Classic 
B1 
Training Manual
Intro – 11Iss. August 2018For instruction only
W
WAAS ...................................Wide Area Augmentation System
WDM .....................................Wiring Diagram Manual
WL ........................................Waterline
WXR .....................................Weather Radar
X
XMSN ...................................Transmission
XPDR....................................Transponder
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EC135 Classic
B1
Training Manual
Intro – Introduction
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1
EC135 Classic 
B1 
Training Manual
01 – 1Iss. August 2018For instruction only
01 – General Information
Chapter 01
General Information
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2
EC135 Classic 
B1 
Training Manual
01 – 2Iss. August 2018For instruction only
Table of contents
1.1 The Development of the EC135 ...................................... 6
1.2 General Description of the EC135 ................................ 10
1.2.1 General ............................................................................ 10
1.2.2 Fuselage .......................................................................... 12
1.2.3 Cabin Dimensions ............................................................ 14
1.3 Maintenance Concept .................................................... 16
1.4 Documentation of the EC135 ........................................ 18
1.4.1 General ............................................................................ 18
1.4.2 Mechanic's Documentation .............................................. 20
1.5 llustrated Parts Catalog ................................................22
1.6 Detailed Part List ........................................................... 24
1.7 Cockpit Arrangement .................................................... 28
1.8 Instrument Panel with CDS ........................................... 30
1.8.1 Triple Indication .............................................................. 32
1.8.2 Torque Indicator ............................................................... 32
1.8.3 Dual TOT Indicator ........................................................... 32
1.8.4 Dual ∆N1 Indicator T1 ...................................................... 34
1.8.5 Dual Indicator ................................................................. 34
1.8.6 Oil Temperature and Pressure Indicator .......................... 36
1.8.7 Cockpit Display System (CDS) ........................................ 38
1.8.8 Configuration ................................................................... 40
1.8.9 CDS Operation ................................................................ 42
1.8.10 CDS Caution Display ....................................................... 44
1.8.11 CDS Advisory Display ...................................................... 48
1.8.12 DISPLAY SELECT Switch / SCROLL Button ................... 48
1.8.13 Engine Parameter Indication ........................................... 52
1.8.14 Torque Indication ............................................................ 52
1.8.15 Electrical Parameter Indication ....................................... 52
1.8.16 Outside Air Indication ...................................................... 52
1.8.17 Mast Moment Indication .................................................. 52
1.8.18 Fuel Indications ............................................................... 52
1.9 Instrument Panel with CPDS ........................................ 54
1.9.1 General ............................................................................ 54
1.9.2 CAD (Caution and Advisory Display) ............................... 56
1.9.3 Color Code Ranges and their Meaning ........................... 58
1.9.4 Function of the CPDS ...................................................... 60
1.9.5 Test Pattern ...................................................................... 62
1.9.6 CPDS Modes ................................................................... 66
1.9.7 CAUTION / FUEL – Page ................................................ 68
1.9.8 CPDS Cautions ................................................................ 70
1.9.9 Advisories ........................................................................ 70
1.9.10 First Limit Page (FLI) P1 / T1 ........................................... 74
1.9.11 FLI ZONE P1 / T1 ............................................................ 76
1.9.12 Limit Light / Counter ......................................................... 76
1.9.13 First Limit Page (FLI) P2 / T2 and P2+ / T2+ ................... 78
1.9.14 High Information Zone ..................................................... 80
01 – General Information
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01 – General Information EC135 Classic 
B1 
Training Manual
01 – 3Iss. August 2018For instruction only
1.9.15 AEO Power Bands ........................................................... 82
1.9.16 OEI Power Bands ........................................................... 82
1.9.17 Limit Light ....................................................................... 82
1.9.18 Countdown Timer ............................................................ 82
1.9.19 ENG EXCEED Caution .................................................... 84
1.9.20 Warnings ......................................................................... 84
1.9.21 Electrical and Vehicle Parameters (ELEC/VEH) .............. 88
1.9.22 VNE ................................................................................. 90
1.9.23 SYSTEM STATUS Page .................................................. 92
1.9.24 Inflight Engine Power Check Page .................................. 98
1.9.25 EPC Fail Page ............................................................... 100
1.9.26 CPDS Switch Over Functions ........................................ 102
1.9.27 Derivative Mode with one VEMD Lane off ..................... 104
1.9.28 Derivative Mode with CAD off ........................................ 106
1.9.29 CAUTION / FUEL FAIL Page ......................................... 108
1.9.30 Backup Mode with CAD and one VEMD Lanes off ........110
1.9.31 Backup Mode with both VEMD Lanes off ......................112
1.9.32 CAUTION / BACKUP Page ............................................114
1.9.33 FLIGHT REPORT Page ..................................................116
1.9.34 Maintenance Menu ........................................................118
1.9.35 Flight Report .................................................................. 120
1.9.36 Failure ............................................................................ 122
1.9.37 Inflight Engine Power Check (Inflight EPC) ................... 126
1.9.38 Transfer Data ................................................................ 128
1.9.39 Functional Times ........................................................... 128
1.9.40 A/C CONFIG Page ........................................................ 132
1.9.41 CPDS Software Versions Overview ............................... 136
1.9.42 Hardware Changes according to H/C Serial Numbers in 
Production ...................................................................... 140
1.10 Warning Unit................................................................. 142
1.10.1 General .......................................................................... 142
1.10.2 AP. A. TRIM ................................................................... 144
1.10.3 Rotor RPM ..................................................................... 144
1.10.4 BAT TEMP ..................................................................... 144
1.10.5 BAT DISCH ................................................................... 144
1.10.6 XMSN OIL P ................................................................. 144
1.10.7 CARGO SMOKE ........................................................... 144
1.10.8 LOW FUEL Warning ..................................................... 144
1.10.9 FIRE Warning with EMER OFF SW Switch ................... 146
1.10.10 Fire Extinguisher System (optional) .............................. 146
1.10.11 N1 RPM Monitoring ...................................................... 146
1.10.12 Audio Warnings ............................................................. 146
1.11 Switch Unit ................................................................... 148
1.12 Overhead Console ....................................................... 150
1.12.1 General .......................................................................... 150
1.12.2 Switch SHED BUS ......................................................... 152
1.13 Pitot–Static System (FCDS) ........................................ 154
1.14 Handling of the EC135 ................................................. 156
1.14.1 Lifting ............................................................................. 156
1.14.2 Jacking ........................................................................... 158
1.14.3 Shoring .......................................................................... 158
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01 – General Information EC135 Classic 
B1 
Training Manual
01 – 4Iss. August 2018For instruction only
1.14.4 Weighing ........................................................................ 160
1.14.5 Towing and Pushing .......................................................162
1.14.6 Parking and Mooring ...................................................... 164
This training document comprises the following ATA chapters:
General Description of the EC135 ATA 06
Maintenance Concept ATA 05, 12
Cockpit Arrangement ATA 31
Instrument Panel with CDS ATA 31
Instrument Panel with CPDS ATA 31
Warning Unit ATA 31
Switch Unit ATA 24, 80
Overhead Console ATA 24
Pitot–Static System (FCDS) ATA 30, 34
Handling of the EC135 ATA 07, 08, 09, 10
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EC135 Classic
B1
Training Manual
01 – General Information
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6
EC135 Classic 
B1 
Training Manual
01 – 6Iss. August 2018For instruction only
01 – General Information
1.1 The Development of the EC135
1.1 The Development of the EC135
History
The first Airbus Helicopters (former, EUROCOPTER, former MBB, 
former BÖLKOW) helicopter with glass fiber rotor blades was the 
single blade helicopter BO 102, a captive trainer, operating for the 
first time in 1957. In 1961 the single seater BO 103 followed, the only 
helicopter to fly with one rotor blade. 
In 1962 / 63, a new hingeless rotor system was created and successfully 
tried on an Alouette II in Marignane, France. 
From 1960 to 1964, the high speed helicopter BO 46 was designed 
with the Derschmidt rotor system. 
In 1964 these helicopters were followed by themulti purpose 2 1/2 ton 
twin engine helicopter BO 105. 
To substitute the BO 105 after 20 years in duty, the BO 108 was 
created and flown on Okt. 15th, 1988 for the first time. Consultations 
with potential customers ‒ operators of Airbus Helicopters products 
and of competing types ‒ showed that cabin volume should be 
increased and visibility improved and that greater emphasis should be 
put on mission flexibility (the cabin floor for instance should be flat and 
unobstructed to allow easy conversion from passenger transportation 
to cargo operation). In late 1992, the design was modified to provide 
accommodation for max. six passengers and two crew members. The 
Aerospatiale developed Fenestron® Anti Torque system was adapted, 
and the EC135 as it is today took shape. 
In the middle of 1996, the certification by the German (LBA) and the 
American Airworthiness Authorities (FAA) was completed.
Engine Versions
The following engine versions are existing:
 – EC135 P1 
equipped with Pratt & Whitney PW 206 B engines. 
 – EC135 P2 / P2+ 
equipped with Pratt & Whitney PW 206 B2 engines. 
 – EC135 P3 
equipped with Pratt & Whitney PW 206 B3 engines. 
 – EC135 T1 
equipped with Turbomeca ARRIUS 2B1, 2B1A, 2B1A_1 
 – EC135 T2 / T2+ 
equipped with Turbomeca ARRIUS 2B2 engines. 
 – EC135 T3 
equipped with Turbomeca ARRIUS 2B2 plus engines
Both engine types are in the 450 kW class. The maximum take–off 
mass for both original versions is 2720 kg (upgrade to 2835 kg MTOM 
is possible), and 2900 kg with external load. 
The EC135 P2+, T2+ is certified for a MTOM of 2910 kg (S/N 505 and 
up). An upgrade up to 2950 kg MTOM (SB EC135-62-028) is possible.
The EC135 P3, T3 is certified for a MTOM of 2980 kg.
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EC135 Classic 
B1 
Training Manual
01 – 7Iss. August 2018For instruction only
EC 135 Variants
01 – General Information
1.1 The Development of the EC135
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01 – General Information
1.1 The Development of the EC135
EC135 Classic 
B1 
Training Manual
01 – 8Iss. August 2018For instruction only
Cockpit Versions
Two major cockpit versions are existing: 
 – CPDS (Central Panel Display System with multifunction 
screens) together with analog flight instruments or as an 
option with FCDS (Flight Control Display System). 
 – CDS (Cockpit Display System) with analog flight instruments 
or EFIS (Electronic Flight Instrument System) 
♦ NOTE CDS Standard cockpit has been replaced by CPDS 
cockpit (S/N 169 and up).
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01 – General Information
1.1 The Development of the EC135
EC135 Classic 
B1 
Training Manual
01 – 9Iss. August 2018For instruction only
EC 135 Variants
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01 – General Information
1.2 General Description of the EC135
1.2.1 General
EC135 Classic 
B1 
Training Manual
01 – 10Iss. August 2018For instruction only
1.2 General Description of the EC135
1.2.1 General
The EC135 is a light multi purpose twin engine helicopter according to 
certification specification for small rotorcraft CS–27 of the European 
Aviation Safety Agency EASA. There are seven seats in the basic 
version, the number can be increased up to eight seats. 
Engines 
The EC135 T is powered by two engines Turbomeca ARRIUS 2B, the 
EC135 P is powered by two engines Pratt &Whitney PW 206 B. They 
are equipped with a digital engine control system. 
Transmission 
The main transmission is a two-stage flat gearbox (produced by 
Zahnradfabrik Friedrichshafen ZF), which is mounted by an anti–
resonance rotor isolation system (ARIS) on the transmission deck. 
Main Rotor 
The helicopter is equipped with a four–bladed hingeless and 
bearingless main rotor (BMR). The inboard flexbeam enables 
movement of the blades in all axes. Blade pitch angles are controlled 
through integrated glass / carbon fibre control cuffs. 
The main rotor control linkage system is of conventional design. The 
hydraulic system for the main rotor controls is designed as a duplex 
system with tandem pistons (both systems are active). In case of a 
failure of one system, the remaining system has sufficient power to 
ensure safe flight operation and a safe landing. 
Tail Rotor System 
The helicopter is equipped with a Fenestron® tail rotor system. There 
are 10 blades rotating in a housing integrated in the tail boom. 
The Fenestron® is controlled via a Flexball type cable, routed from the 
pedals to the input control rod of the Fenestron®. 
Tail Boom 
The tail boom can be separated from the fuselage, and consists of 
tail boom cone, horizontal stabilizer with end–plates, vertical fin with 
integrated tail rotor, tail rotor gearbox and fairing. 
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EC135 Classic 
B1 
Training Manual
01 – 11Iss. August 2018For instruction only
External Dimensions (P1, P2, P2+, T1, T2, T2+)
01 – General Information
1.2 General Description of the EC135
1.2.1 General
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01 – General Information
1.2 General Description of the EC135
1.2.2 Fuselage
EC135 Classic 
B1 
Training Manual
01 – 12Iss. August 2018For instruction only
1.2.2 Fuselage
The primary structure consists mainly of sheet metal design. Cabin 
frame, bottom shell, doors, engine cowling, nose access panel and 
the entire tail boom are made of composite material. 
The cabin is accessible through six doors: two hinged doors for the 
crew, two sliding doors for the passengers, and two aft clamshell 
doors for the rear compartment. 
Fuel System 
The fuel system comprises two fuel tanks, a fuel supply system, a 
refueling and grounding equipment and a monitoring system. The 
main tank and the separated supply tankwith overflowto themain tank 
are installed under the cabin floor. 
ElectricalSystem 
The fully redundant electrical 28 VDC system is supplied by two 
generators and the battery. 
Landing Gear 
The EC135 has two cross tubes and two skids. The cross tubes are 
constructed to be bent to absorb forces during touch down of the 
helicopter.
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EC135 Classic 
B1 
Training Manual
01 – 13Iss. August 2018For instruction only
External Dimensions (P3 / T3)
01 – General Information
1.2.2 Fuselage
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01 – General Information
1.2 General Description of the EC135
1.2.3 Cabin Dimensions
EC135 Classic 
B1 
Training Manual
01 – 14Iss. August 2018For instruction only
1.2.3 Cabin Dimensions
For the cabin dimensions refer to the following graphic.
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EC135 Classic 
B1 
Training Manual
01 – 15Iss. August 2018For instruction only
Cabin Dimensions (P1, P2, P2+, P3, T1, T2, T2+, T3)
01 – General Information
1.2.3 Cabin Dimensions
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01 – General Information
1.3 Maintenance Concept
1.2.3 Cabin Dimensions
EC135 Classic 
B1 
Training Manual
01 – 16Iss. August 2018For instruction only
1.3 Maintenance Concept
General 
Maintenance covers all scheduled and unscheduled maintenance 
activities. It also applies to the on condition maintenance. It is based 
on condition monitoring by visual checks / inspections and diagnostic 
features such as chip detectors, filter bypass indicators, boroscope 
access, failure code indications, built–in tests, warning lights etc.
Maintenance Levels 
EC135 maintenance is split into three maintenance levels: 
 – Organizational Level (O) 
 – Intermediate Level (I) 
 – Depot Level (D) 
Organizational Level 
The organizational level covers tasks of the daily servicing, maintenance 
checks, inspections for condition, exchange of components (LRU’s) 
and quick, simple repairs as specified in the aircraft maintenance 
manual (AMM).
The work generally takes place at the operator’s site, according to 
national regulations. 
Intermediate Level 
The intermediate level covers repairs on/off helicopter and extended 
periodical inspections as specified in the AMM. To fulfill these tasks, 
maintenance facility, qualified personel, test equipment and special 
tools are required.
♦ NOTE The maintenance manual covers all tasks of 
organizational level and intermediate level. 
Depot Level (D) 
Depot level covers major repair or overhaul at the manufacturer or at 
authorized service stations under industrial premises. 
More extensive tools / test equipment and specialized personnel are 
necessary.
♦ NOTE Documentation and spares for depot level tasks will 
be delivered to authorized customers only.
♦ NOTE Information about inspections and intervals are to 
be found in chapter 10 of this training manual.
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EC135 Classic 
B1 
Training Manual
01 – 17Iss. August 2018For instruction only
Maintenance Concept
01 – General Information
1.3 Maintenance Concept
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01 – General Information
1.4 Documentation of the EC135
1.4.1 General
EC135 Classic 
B1 
Training Manual
01 – 18Iss. August 2018For instruction only
1.4 Documentation of the EC135
1.4.1 General
The documentation of the EC135 consists of two main groups:
 – EC135 helicopter documentation written by Airbus Helicopters 
 – other manufacturers’ documentations. 
The whole documentation library is prepared in general compliance 
with Air Transport Association Specification ATA iSpec2200. The 
customized documentation is available for certain H/C serial numbers 
or a group of H/C serial numbers. 
Revision / Reissue 
Changes in the helicopter equipment, maintenance practices, 
procedures etc. make it necessary to update the manual content. The 
documents are distributed by paper, DVD or online.
ATA Numbering 
The numbering system provides a procedure for dividing material into 
chapter, section, subject and page. The number is composed of three 
elements, which have two numbers each. The chapter and section 
element are established by ATA iSpec2200. Subject and unit element 
numbers are assigned by AHD. 
Page Number Blocks 
Page number blocks are used for the different sections of the 
maintenance manual to logically place the activities in sequence as 
follows: Procedures have either a brief subtopic or a combination of 
subtopics i.e. Removal / Installation, Inspection / Test. If subtopics 
are brief, then they are combined in one topic under Maintenance 
Practices. If the subtopics become too long so that a combination 
would require numerous pages, the topics are broken up into page 
number blocks. 
 – Pageblock 1– 99 System Description 
 – Pageblock 101–199 Troubleshooting 
 – Pageblock 201–299 Maintenance Procedures 
 – Pageblock 301–399 Servicing 
 – Pageblock 401–499 Removal/Installation 
 – Pageblock 501–599 Adjustment/Test 
 – Pageblock 601–699 Inspection 
 – Pageblock 701–799 Cleaning/Painting 
 – Pageblock 801–899 Repair 
 – Pageblock 901–999 Storage 
♦ NOTE Element 1, element 2 and the pageblocks are set 
by the ATA iSpec2200 schematic. The following 
elements can be defined by the aircraft manufacturer 
as required.
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EC135 Classic 
B1 
Training Manual
01 – 19Iss. August 2018For instruction only
ATA Numbering
01 – General Information
1.4 Documentation of the EC135
1.4.1 General
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01 – General Information
1.4 Documentation of the EC135
1.4.2 Mechanic's Documentation
EC135 Classic 
B1 
Training Manual
01 – 20Iss. August 2018For instruction only
1.4.2 Mechanic's Documentation
The mechanic’s documentation compromises of: 
 – Aircraft Maintenance Manual (AMM) 
 – Systems Description Section (SDS) 
 – Master Servicing Manual (MSM) 
 – Wiring Diagram Manual (WDM) 
 – Illustrated Parts Catalog including Tools Catalog (IPC) 
 – Corrosion and Erosion Control Guide (CECG) 
 – Avionic Manual (AVM)
 – Standard Practices Manual (MTC) 
 – Structural Repair Manual (SRM)
 – Electronic Component Maintenance Manual (ECMM)
 – E-RepairR (ERR) 
The AMM, SDS and WDM are available in customized versions. The 
customer can choose in between the following variants: 
 – Serial number documentation system (one S/N only) 
 – Fleet documentation system (several S/N) 
 – Global documentation system (all S/N) 
Operator’s Technical Control Documentation 
The following documents are kept by the operator’s technical control: 
 – Historical Record 
 – Status Revision Documentation (SRD / LOAP)
 – Service Bulletins (SB) / Alert Service Bulletins (ASB)
 – Emergency Alert Service Bulletins (EASB)
 – Information Notice (IN) / Safety Information Notice (SIN)
 – Technical Improvement Proposal (TIP) 
Pilot’s Documentation 
The pilot has four documents available:
 – Master Minimum Equipment List (MMEL) 
 – Flight Manual (FLM), according Helicopter Association 
International, (HAI)
 – Log Book 
 – Pilot’s Checklist (PCL) 
♦ NOTE The Flight Manual and the Log Book must always be 
present in the helicopter. 
Other Manufacturer’s Documentation 
The other manufacturers (engines, avionics and optional equipment) 
deliver their own documentation:– Engine Maintenance Manual 
 – Engine Illustrated Parts Catalog 
 – Engine Service Bulletins / Service Letters 
 – Component Maintenance Manuals (CMM) 
 – Special optional equipment (e.g. external hoist system) 
♦ NOTE The valid manuals incl. the revision status are 
published in the SRD, formally List of Applicable 
Publications (LOAP).
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EC135 Classic 
B1 
Training Manual
01 – 21Iss. August 2018For instruction only
Helicopter Documentation
01 – General Information
1.4.2 Mechanic's Documentation
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01 – General Information
1.5 llustrated Parts Catalog
1.4.2 Mechanic's Documentation
EC135 Classic 
B1 
Training Manual
01 – 22Iss. August 2018For instruction only
1.5 llustrated Parts Catalog
General
The Illustrated Parts Catalog (IPC) contains exploded views of parts 
belonging to the EC135. The arrangement of the IPC is shown in the 
figure below and is described in the following. 
Manual Structure 
The IPC consists of three main parts. Each main part is divided into 
several sections: 
 – First part: General Information 
The general information contains the record of revisions 
and temporary revisions, a chapter listing, an introduction 
explaining how to use the catalog, a list of effective pages, a 
table of content, a vendor list, a list of all incorporated service 
bulletins and a list of abbreviations;
 – Second Part: Part Numerical Index and Electrical Identifier 
Index contains two alpha–numerical listings, one of all 
electrical identification indices, designator equipment 
orientated and one of all part numbers, P/N orientated;
 – Third Part: Detailed Parts List 
“Detailed Parts List“ contains of the illustrated nomenclatures 
orientated by ATA chapter.
Page Numbering
The pages of the first part (RECORD OF REVISIONS / RECORD 
OF TEMPORARY REVISIONS, LOEP, INTRODUCTION, TABLE OF 
CONTENTS, SERVICE BULLETIN LIST, LIST OF ABBREVIATIONS) 
are numbered consecutively within each section.
The pages of the second part (PART NUMERICAL INDEX, 
ELECTRICAL IDENTIFIER INDEX) are numbered consecutively 
within each section.
The pages of the third part (DETAILED PART LIST) are consecutively 
numbered within each figure.
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EC135 Classic 
B1 
Training Manual
01 – 23Iss. August 2018For instruction only
Illustrated Parts Catalog
01 – General Information
1.5 llustrated Parts Catalog
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01 – General Information
1.6 Detailed Part List
1.4.2 Mechanic's Documentation
EC135 Classic 
B1 
Training Manual
01 – 24Iss. August 2018For instruction only
1.6 Detailed Part List
Figure Number 
The Figure Number refers to the corresponding illustration. 
If modification or system variant necessitate an additional figure this 
will be introduced with a sequential alphasuffix, for example a modified 
version to Fig. 1 would be Fig. 1A ; further variant of the same Figure 
would be Fig. 1B and so on. 
Item Number 
The item number corresponds to the item number shown for the part 
in the illustration. Items are initially numbered 10 by 10. 
A modification implies the addition of a part between two existing 
parts; this new part will be inserted with the item number 5 to allow 
further additions. 
Example: a part inserted between item 100 and 110 will be entered as 
105, between 105 and 110 as item 108, and so on. Alpha variants are 
used to indicate evolution of parts. Parts with item numbers preceded 
by a dash are not illustrated. 
Part Number Column 
Each part, assembly or installation is assigned a “Part Number” showing 
the manufacturer part number, vendor part number or standard part 
number. This part number has to be used for ordering spare parts. 
The term “NO NUMBER” is used within the PART NUMBER column 
if a specific grouping of parts is required for establishing the most 
suitable breakdown. 
Sequence of Breakdown of the list 
This sequence includes up to 7 steps: 
Installation 
● Part of Installation
● Assy
● Attaching Parts of Assy 
● – – – – – – – * ● – – – – – – – 
● ● Detail Parts of Sub–Assy 
● ● Sub–Assy 
● ● Attaching Parts of Sub--Assy 
● ● – – – – – – – * ● – – – – – – –
● ● ● Detail Parts of Sub–Assy 
● ● ● Secondary Sub–Assy 
● ● ● Attaching Parts of Secondary Sub–Assy 
● – – – – – – – * ● – – – – – – –
● ● ● ● Detail Parts of Secondary Sub–Assy etc ... up to 7th step
Fig. 01-1: Sequence of Breakdown of the list
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EC135 Classic 
B1 
Training Manual
01 – 25Iss. August 2018For instruction only
Example Part Number
01 – General Information
1.6 Detailed Part List
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EC135 Classic 
B1 
Training Manual
01 – 26Iss. August 2018For instruction only
INTENTIONALLy LEFT BLANK
01 – General Information
1.6 Detailed Part List
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EC135 Classic 
B1 
Training Manual
01 – 27Iss. August 2018For instruction only
Illustrated Parts Catalog
01 – General Information
1.6 Detailed Part List
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01 – General Information
1.7 Cockpit Arrangement
1.4.2 Mechanic's Documentation
EC135 Classic 
B1 
Training Manual
01 – 28Iss. August 2018For instruction only
1.7 Cockpit Arrangement
General 
The EC135 is provided with several units for monitoring, warning and 
control purposes. 
Flight Controls 
The flight controls within the cockpit comprise the following elements: 
 – cyclic stick 
 – collective lever 
 – pedals 
 – center post (encases the vertical control rods). 
Overhead Console 
The overhead console carries the most important circuit breakers and 
several control switches. 
Center Instrument Panel 
The center of the instrument panel contains the CDS (Cockpit Display 
System) in earlier versions or the CPDS (Central Panel Display 
System) with analog back up instruments. The warning unit displays 
system / engine conditions. A chronograph is also included. A number 
of switches for engine and electrical system operation are located on 
the center instrument panel, too.
RH Pilot’s Extension 
The RH section of the instrument panel contains the instruments / 
displays for flight control and navigation. A number of switches may 
be provided for controlling the radio / navigation system. A nozzle is 
provided for regulating fresh air supply. 
LH Copilot’s Extension 
The LH section of the instrument panel is specified for the copilot. 
The configuration of the LH section varies according to helicopter 
equipment. 
Slant Console 
The slant console houses the COM / NAV control panels. 
Center Console
Within the center console, the control panels for the optional equipment 
are mounted.
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EC135 Classic 
B1 
Training Manual
01 – 29Iss. August 2018For instruction only
Cockpit Arrangement (CPDS, FCDS)
01 – General Information
1.7 Cockpit Arrangement
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01 – General Information
1.8 Instrument Panel with CDS
1.4.2 Mechanic's DocumentationEC135 Classic 
B1 
Training Manual
01 – 30Iss. August 2018For instruction only
1.8 Instrument Panel with CDS
General
All the instruments and indications for monitoring the helicopter 
systems are installed in the center section of the instrument panel.
Configuration 
The following instruments, indicators and switches are installed in the 
center section of the instrument panel:
 – Warning unit 
 – triple RPM indicator (NR and N2 from engine one and two)
 – torque indicator 
 – dual TOT indicator 
 – dual ∆N1 indicator (T1 only) 
 – dual N1 indicator (P1 only) 
 – chronograph 
 – switch unit
 – oil temperature and pressure indicators for engines and main 
transmission
 – Cockpit Display System (CDS).
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EC135 Classic 
B1 
Training Manual
01 – 31Iss. August 2018For instruction only
Instrument Panel (CDS, Analog Flight Instruments)
01 – General Information
1.8 Instrument Panel with CDS
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01 – General Information
1.8 Instrument Panel with CDS
1.8.1 Triple RPM Indication
EC135 Classic 
B1 
Training Manual
01 – 32Iss. August 2018For instruction only
1.8.1 Triple RPM Indication
General 
The triple RPM indicator is part of the speed sensing system. It is a 
3–pointer instrument and indicates the RPM of the following:
 – rotor RPM [ % ] 
 – power turbine speed engine 1 [ % ] 
 – power turbine speed engine 2 [ % ]
Operation
The system is combined of inductive pickups at the engines and at the 
main transmission, each generating a voltage peak whenever a tooth 
of the appropriate gear passes. 
Rotor RPM 
The rotor RPM is indicated by the small pointer labelled “R”. The 
indication range is 0 to 120 %. 
Power Turbine Speed N2 
The power turbine speed of engine 1 and engine 2 is indicated by 2 
pointers, labelled “1” and “2”. The indication range is 0 to 120 %.
1.8.2 Torque Indicator
General
The torque indicator shows the torque, measured at each engine 
output shaft. It is a 2–pointer instrument. The pointers are labelled “1” 
and “2”. 
The indication range is 0 to 140 %.
1.8.3 Dual TOT Indicator
General
The TOT indicator shows the turbine outlet temperature at each 
engine. It is a 2–pointer instrument. The pointers are labelled “1” 
and “2”. 
The indication range is 0 to 100 °C x 10.
♦ NOTE The limit values may be different according to the 
engine version installed.
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EC135 Classic 
B1 
Training Manual
01 – 33Iss. August 2018For instruction only
Engine Monitoring Instruments TM
01 – General Information
1.8.3 Dual TOT Indicator
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01 – General Information
1.8 Instrument Panel with CDS
1.8.4 Dual ∆N1 Indicator T1
EC135 Classic 
B1 
Training Manual
01 – 34Iss. August 2018For instruction only
1.8.4 Dual ∆N1 Indicator T1
General
The dual ∆N1 indicator is part of the speed sensing system. It is a 2–
pointer instrument and indicates the RPM of the following: 
 – ∆ gas producer RPM between the max. allowed (computed 
by the FADEC) RPM and the present RPM for engine 1 and 
engine 2. 
The pointers are labelled “1” and “2”. The indication range is from - 
8 % to + 4 %.
1.8.5 Dual N1 Indicator P1
General
The dual N1 indicator is part of the speed sensing system. It is a 2–
pointer instrument and indicates the RPM of the following:
 – gas producer RPM for engine 1 and engine 2. 
The pointers are labelled “1” and “2”. The indication range is from 0 % 
to + 120 %.
♦ NOTE The limit values may be different according to the 
engine version installed.
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EC135 Classic 
B1 
Training Manual
01 – 35Iss. August 2018For instruction only
Engine Monitoring Instruments P1
01 – General Information
1.8.5 Dual N1 Indicator P1
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01 – General Information
1.8 Instrument Panel with CDS
1.8.6 Oil Temperature and Pressure Indicator
EC135 Classic 
B1 
Training Manual
01 – 36Iss. August 2018For instruction only
1.8.6 Oil Temperature and Pressure Indicator
General
The oil temperature and pressure indicator is an instrument cluster 
indicating oil temperature and oil pressure for each engine and for the 
main transmission on six individual indicators. 
 – The temperature is shown in °C. 
 – The pressure is shown in bar.
According to the engine type installed (TM or PW), the indicators have 
different scaling and different limit markers. 
The indicator lighting is adjusted with the potentiometer INSTR in the 
overhead panel.
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EC135 Classic 
B1 
Training Manual
01 – 37Iss. August 2018For instruction only
Oil Temperature and Pressure Indicator
01 – General Information
1.8.6 Oil Temperature and Pressure Indicator
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01 – General Information
1.8 Instrument Panel with CDS
1.8.7 Cockpit Display System (CDS)
EC135 Classic 
B1 
Training Manual
01 – 38Iss. August 2018For instruction only
1.8.7 Cockpit Display System (CDS)
Introduction
The Cockpit Display System (CDS) provides indication of aircraft 
status information such as caution and advisory messages. It consists 
of a self contained unit installed in the center section of the instrument 
panel. 
Various switches facilitate operation of the device and allow control of 
the indications. The brightness is automatically controlled with the aid 
of a sensor. 
If internal malfunctions are detected during the self test, the annunciator 
“CDS FAIL” illuminates at the front panel oft the CDS. Additionally the 
caution “CDS FAILED” is displayed at the Caution Display centre part 
(MISC). 
The CDS is capable of identifying the type of engine installed according 
to the wiring of the connectors. 
The casing of the CDS is cooled by the cabin ventilation system or the 
air-conditioning system, if installed. 
Associated Controls and Indicators 
In order to provide proper function and handling, the following controls 
and indicators beside the CDS are available:
 – MASTER CAUTION light 
The MASTER CAUTION light is installed in the center part of the 
instrument panel RH of the warning unit. 
 – Switch CDS/AUDIO RES 
The switch CDS/AUDIO RES is installed in the grip of the cyclic 
control stick and enables the pilot and copilot (if dual pilot controls are 
installed) to acknowledge the cautions. 
 – Test switch TEST/CDS 
The test switch TEST/CDS is installed in the overhead panel. It triggers 
the testing of the CDS indications. 
 – CDS OVTP light 
The CDS OVTP indication light is installed in the center part of the 
instrument panel below the CDS on the left side. The light comes on if 
the internal temperature is higher than 63 °C. 
Power Supply 
In order to guarantee continuous operation even in the event of 
failure of one of the essential busbars, the CDS is supplied by both 
ESSENTIAL busbars via the circuit breakers located in the overhead 
panel. 
 – CDS / SYS 1 
 – CDS / SYS 2 
Data Storage 
A CDS integrated memory has two functions which are as follows: 
 – Storage of all of the CAUTION indications having occurred 
within the penultimate minute. 
 – Storage of the failures reported to the CDS by the engine 
control units along with their respectivefailure codes.
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EC135 Classic 
B1 
Training Manual
01 – 39Iss. August 2018For instruction only
CDS - General Arrangement
01 – General Information
1.8.7 Cockpit Display System (CDS)
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01 – General Information
1.8 Instrument Panel with CDS
1.8.8 Configuration
EC135 Classic 
B1 
Training Manual
01 – 40Iss. August 2018For instruction only
1.8.8 Configuration
The CDS provides the crew with information while at the same time 
indicating the present state of various systems of the helicopter. 
The CDS performs the following tasks: 
 – Caution indication 
 – Advisory indication 
 – indication of engine parameter (engine cycle counter), 
FADEC-MEM-codes and malfunction indications 
 – indication of helicopter’s power supply voltage and current 
 – outside air temperature indication 
 – mast moment bargraph with limit warning light* 
 – fuel system indication 
 – calculation and indication of Vne velocity ** 
 – radar altimeter indication 
 – indication of length of rescue winch cable* 
 – indication of load attached to external cargo hook* 
 – engine operating hours counter. 
* Only available when the resp. systems are installed in the helicopter. 
** The WEIGHT key (Vne) is installed in early CDS versions only. 
The CDS is divided into several panels to enhance overall view. Each 
of these panels serve assigned functions. 
The basic brightness of the indications is controlled through the keys 
BRIGHTNESS. 
Colors of Indications 
Amber:
The upper displaywhich is the primary display is split into four sections. 
In the upper part cautions are displayed separately for SYST I/II and 
MISC. The color of the cautions is amber. 
Green: 
The lower part of the upper display shows the advisories The color of 
the advisories is green. 
White: 
The color in the lower displaywhich is the secondary display in general 
is white. 
Exceptions are made with the mast moment indication which is green 
- yellow - red and fuel low indications in the fuel display which are red.
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EC135 Classic 
B1 
Training Manual
01 – 41Iss. August 2018For instruction only
CDS - Display and Controls
01 – General Information
1.8.8 Configuration
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1.8 Instrument Panel with CDS
1.8.9 CDS Operation
EC135 Classic 
B1 
Training Manual
01 – 42Iss. August 2018For instruction only
1.8.9 CDS Operation
Power Supply and Self Test 
The CDS is activated by setting the battery master switch BAT MSTR 
in ON position. This causes the CDS self test to be carried out. The 
CDS checks also the presence of the following engine cautions for 
SYS I and SYS II: Engine Cautions 
ENG FAIL ENG FAIL
ENG OIL P ENG OIL P
FUEL PRESS FUEL PRESS
HYD PRESS HYD PRESS
XMSN OIL P XMSN OIL P
GEN DISCON GEN DISCON
If the cautions have been successfully detected INP PASSED comes 
on on the advisory display below the message CDS PASSED and 
engine configuration (early CDS versions only). If a caution is missing, 
INP FAIL appears in the center column of the caution display, followed 
by the missing caution to the left / right. 
The pilot has to acknowledge the messages by pushing the CDS/AUDIO 
RES button on the stick grip. Subsequent to the acknowledgement the 
CDS starts normal operation. If the self test was not successful CDS 
FAIL will appear on the display. 
The indication light CDS FAIL comes on only when the CDS self test 
is faulty.
Mast Moment Failure
If there is a failure of the mast moment system detected, the caution 
MM FAILED comes up in the MISC field (depends on the part number). 
Continuity Test 
Continuity tests of the connecting cables between some sensors 
and the CDS are made during CDS power – ON self test. A failure 
is indicated by displaying the respective detector name with an 
additional ...CT at the end of the respective caution. If a ...CT – caution 
is indicated, the monitoring circuit of the corresponding system must 
be assumed to be unable to activate the real system caution in case 
of system failure. 
CDS Test Switch 
The CDS test switch, located on the test switch panel of the overhead 
console provides test function of the display screen and lights of the 
CDS. Activation of the test switch causes the screen, the lights of the 
CDS and the CDS OVTP light to illuminate.
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B1 
Training Manual
01 – 43Iss. August 2018For instruction only
CDS Self Test
01 – General Information
1.8.9 CDS Operation
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01 – General Information
1.8 Instrument Panel with CDS
1.8.10 CDS Caution Display
EC135 Classic 
B1 
Training Manual
01 – 44Iss. August 2018For instruction only
1.8.10 CDS Caution Display
General
The cautions are displayed in the CAUTION display, separately for 
system 1, system 2 and miscellaneous. 
New cautions emerging on the screen are accompanied by flashing 
bars above and below the caution. Cautions displayed before are 
extinguished from the display but stored in the background. 
Each new caution indication causes the MASTER CAUTION light to 
come on (The master caution light is located right beside the warning 
panel). 
The cautions must be acknowledged by pressing the CDS/AUDIO 
RES button which is located on the cyclic stick. 
After pressing the CDS/AUDIO RES button the MASTER CAUTION 
light goes off and the CDS changes to the prioritized display mode. 
That means, that all active cautions are displayed in sequence of 
priority.
If there are more acknowledged cautions than can be displayed on the 
screen simultaneously, the PAGE light illuminates and the additional 
cautions can be called up from the second page by pressing the 
CAUTION PAGE button. If the CAUTION PAGE button has not been 
pressed for 10 seconds, the top priority cautions are displayed.
♦ NOTE The following two listings show all possible cautions 
/ advisories at the time this manual has been 
printed. The caution configuration in the individual 
helicopter depends on the helicopter serial number, 
CDS configuration and optional equipment installed. 
The cautions will be explained in the respective 
chapters.
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EC135 Classic 
B1 
Training Manual
01 – 45Iss. August 2018For instruction only
Advisory Display, Display Select and Scroll Switch
01 – General Information
1.8.10 CDS Caution Display
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01 – General Information
1.8 Instrument Panel with CDS
1.8.10 CDS Caution Display
EC135 Classic 
B1 
Training Manual
01 – 46Iss. August 2018For instruction only
CDS Priority of Cautions
SyS I / II MISC
1 ENG FAIL CDS PWR
2 ENG OIL P XMSN CHIP
3 ENG CHIP TRGB CHIP
4 FADEC FAIL XMSN OIL T
5 FUEL PRESS ROTOR BRAKE
6 FUEL FILT AUTOPILOT
7 ENG O FILT DOORS
8 ENG EXCEED TRIM
9 ENG MANUAL GYRO
10 TWIST GRIP ACTUATION
11 FUEL VALVE F PUMP AFT
12 F VALVE CL F PUMP FWD
13 FADEC MINR (PW only) F QTY FAIL
14 DEGRADE (TM only) F QTY DEGR
15 REDUND (TM only) HTG OVTEMP
16 PRIME PUMP EPU DOOR
17 HYD PRESS BAT DISCON
18 XMSN OIL P EXT POWER
19 OVSP (TM only) SHED EMER
20 OVSP FAIL (TM only) DG
21 GEN OVHT HOR BAT
22 GEN DISCON APREDUCED
23 INVERTER ADC
24 FIRE EXT FLOATS ARM
25 FIRE E TST DECOUPLE
26 BUSTIE OPN AVAD FAIL
27 STARTER P/R SAS
28 ENG CHIP CT YAW SAS
29 ENG OF CT XMSN CHP CT
30 F FILT CT XMSN OT CT
31 INP FAIL TRGB CHP CT
32 INP PASSED MM FAIL
33 DAMPER
34 CDS TEMP
35 ALT ALERT
36 MSG
37 AUX F XFER
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01 – General Information
1.8.10 CDS Caution Display
EC135 Classic 
B1 
Training Manual
01 – 47Iss. August 2018For instruction only
Advisory Display, Display Select and Scroll Switch
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01 – General Information
1.8 Instrument Panel with CDS
1.8.11 CDS Advisory Display
EC135 Classic 
B1 
Training Manual
01 – 48Iss. August 2018For instruction only
1.8.11 CDS Advisory Display
General 
The section below the caution display contains the advisory display 
which keeps the pilot informed about operating conditions of additional 
equipment which is not essential for the flight. 
The following advisories are possible (depending on optional 
equipment):
Tab. 01-3: CDS Advisories
BLEED AIR Bleed air supply has been activated
LDG LIGHT Standard and/or optional landing light on
P/S-HTR-P Heating of the pitot pilot side is active
P/S-HTR-CP Heating of the pilot copilot side is active
LDG L RETR Search and landing light retracts at rest
LDG L EXTD Search and landing light extended
AIR COND Air condition system active
HOOK UNLD Load is < 5 kg
AX FVLV CL Aux. fuel valve is in closed position
CA CUT ARM Cable cut circuit test is passed
IR Infra red light is active
IFCO The IR filter is pivoted in front of the SX16
SAND FILT The sand filter is active
1.8.12 DISPLAy SELECT Switch / SCROLL Button
General
The DISPLAY SELECT switch has six selectable positions which 
provide information and data about several engine parameters, failure 
codes, operation parameters etc. 
The information can be displayed by selecting a certain switch position 
and pressing the SCROLL buttons to scroll within the respective line. 
Selectable Parameters 
The following table describes the possible parameters in dependency 
on the chosen DISPLAY SELECT switch position.
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01 – General Information
1.8.12 DISPLAY SELECT Switch / SCROLL Button
EC135 Classic 
B1 
Training Manual
01 – 49Iss. August 2018For instruction only
Advisory Display, Display Select and Scroll Switch
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Training Manual
01 – 50Iss. August 2018For instruction only
01 – General Information
1.8.12 DISPLAY SELECT Switch / SCROLL Button
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Training Manual
01 – 51Iss. August 2018For instruction only
01 – General Information
1.8.12 DISPLAY SELECT Switch / SCROLL Button
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01 – General Information
1.8 Instrument Panel with CDS
1.8.13 Engine Parameter Indication
EC135 Classic 
B1 
Training Manual
01 – 52Iss. August 2018For instruction only
1.8.13 Engine Parameter Indication
In the upper line of the CDS display the FADEC provided engine 
parameters can be displayed. 
1.8.14 Torque Indication 
The torque is permanently displayed on the TORQUE display in %.
1.8.15 Electrical Parameter Indication 
The aircraft‘s electrical voltages and currents can be shown on the 
electrical system display. The VOLT / AMP button enables the crew 
to select between DC VOLTS, GEN AMPS or BAT AMPS. The default 
setting is DC VOLTS. 
1.8.16 Outside Air Indication 
Outside air temperature is permanently displayed in °C. The value is 
also internally used for VNE calculation. 
1.8.17 Mast Moment Indication 
The EC135 is equipped with a hingeless and bearingless rotor 
system and therefore high bending moments occur at the rotormast, 
particularly during close ground operation. The bending of the main 
rotor hub–shaft is monitored by a mast moment measuring system.
The mast moment indication consists of a bargraph and a limit light.
The bargraph is a three–color indication, indicating the mast moment 
linear from 0 to 100 % in green, yellow and finally red. 
The limit light remains on until a “cold start” of the CDS occurs. 
If the input signal from the mast moment measuring system is out of 
specified values, the caution MM FAIL will be displayed. 
1.8.18 Fuel Indications 
The CDS displays the fuel masses and fuel system status of the supply 
tank 1, supply tank 2, main tank and (if installed) auxiliary tank. Each 
of the tank displays contain a bargraph display and a numeric display. 
The supply 1 and supply 2 displays contain a red LOW indication 
which illuminates when the resp. tank‘s content is below a specified 
value. 
The FREE indication comes on when the free volume of the main tank 
is greater than the current volume of the auxiliary tank. 
The XFER indication comes on when fuel is being transferred into the 
main tank (transfer valve open).
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EC135 Classic 
B1 
Training Manual
01 – 53Iss. August 2018For instruction only
System Parameter Indications
01 – General Information
1.8.18 Fuel Indications 
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.1 General
EC135 Classic 
B1 
Training Manual
01 – 54Iss. August 2018For instruction only
1.9 Instrument Panel with CPDS
1.9.1 General
The Central Panel Display System is an electronic indicating system 
and presents various parameters of the onboard systems on three 
screens. 
The instrument panel contains most of the displays and instruments and 
some of the control units installed in the helicopter. The configuration 
of the instrument panel varies according to operators needs and the 
associated equipment.
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B1 
Training Manual
01 – 55Iss. August 2018For instruction only
Instrument Panel (CPDS, FCDS)
01 – General Information
1.9 Instrument Panel with CPDS
1.9.1 General
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.2 CAD (Caution and Advisory Display)
EC135 Classic 
B1 
Training Manual
01 – 56Iss. August 2018For instruction only
1.9.2 CAD (Caution and Advisory Display)
The CAD displays cautions, advisory messages and fuel system 
indications. The CAD consists of one screen and one processing 
module (lane), both of which are integrated in a common housing. If 
the VEMD or one of its modules/screens fail, the CAD can take over 
and display selected parameters from it. 
The display instrument of the CAD consists of a color screen, integrated 
in the left-hand side of the center section of the instrument panel. 
VEMD (Vehicle and Engine Monitoring Display) 
The VEMD will display engine and dynamic system parameters. In 
addition, it can present data relating to onboard systems (e.g. aircraft 
electrical system, autopilot) and to optional equipment (e.g. cargo 
hook). 
The VEMD consists of a housing with two integral screens and two 
processing modules (lanes) which are each plugged intoone of the 
screenswithin the housing. Although they are logically linked, they can 
also operate independent of each other.
If the CAD fails, the VEMD displays selected CAUTIONs. The 
duplex configuration of the VEMD provides redundancy so that two 
processing modules are each individually capable of taking over most 
of the tasks. 
Both the VEMD screens are installed on the right-hand side of the 
center section of the instrument panel. 
Test Switch 
The test switch triggers the CPDS to display the test page with the 
complete color spectrum and the software version. 
Circuit Breakers 
The CAD and the VEMD are supplied with voltage, each via two circuit 
breakers, from the ESSENTIAL busbars 1 and 2. The circuit breakers 
are arranged in the overhead panel. 
CDS/AUDIO RES Switch 
The CDS/AUDIO RES switch is used by the pilot and copilot to 
acknowledge displayed cautions. It has the same function as the 
SELECT key on the CAD. The switch is installed in the grip of the 
pilot’s cyclic stick and, if dual controls are installed, one is also installed 
in the copilot’s cyclic stick grip. 
Voltage Adjusting Element 
An adjusting element for each voltage indication of the VEMD is 
integrated in the sensor units 41VE / 42VE, mounted to the inner side 
of the bottom shell, accessable through the forward access panel. 
With the adjusting element the voltage reading on the VEMD can be 
corrected. 
Maintenance Connector 
Two maintenance connectors are mounted to the rear part of the slant 
console (S/N 218 and up). 
CPDS OVHT Caution 
The CPDS OVHT caution is triggered by a temperature switch in the 
instrument panel. If the temperature exceeds a specified value, the 
vent blower will be switched on automatically in order to avoid an 
overtemperature situation.
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EC135 Classic 
B1 
Training Manual
01 – 57Iss. August 2018For instruction only
CAD and VEMD
01 – General Information
1.9.2 CAD (Caution and Advisory Display)
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.3 Color Code Ranges and their Meaning
EC135 Classic 
B1 
Training Manual
01 – 58Iss. August 2018For instruction only
1.9.3 Color Code Ranges and their Meaning
The range of colors used for displays on the screens of the CPDS 
covers different colors in addition to black and white. Each individual 
color has a specific significance.
Black Background, text on colored background
White Scales, display arrows (pointers), numbers, etc.
Yellow Limits, defect symbols, cautions, messages
Red Limits, warnings
Green Advisories
Cyan Tech. units, selections, demarcations etc.
Blue Fuel quantity level
CAD Operation
The CAD is operated by the following keys in the front panel:
Key Function
OFF Switches CAD on / off
SCROLL Selects different screen pages (e.g. second page with cautions)
SELECT Acknowledges new cautions
BRT + Increases brightness of screen
BRT - Decreases brightness of screen
VEMD Operation
The VEMD is operated by the following keys located on the front panel 
of the display monitor:
Key Function
OFF 1 Switches upper screen and processing module 1 on / off
OFF 2 Switches lower screen and processing module 2 on / off
SCROLL Scrolls to next page, depending on operating mode and status
RESET Initiates return to normal screen display or to previously displayed page (depending on the operating mode)
SELECT Selects a particular data field
+ / - Input of changes to data field
ENTER Acknowledges selection of a data field or a data entry to a data field
BRT + Increases brightness of screen by continuous adjustment
BRT - Decreases brightness of screen by continuous adjustment
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EC135 Classic 
B1 
Training Manual
01 – 59Iss. August 2018For instruction only
CPDS (Example)
01 – General Information
1.9.3 Color Code Ranges and their Meaning
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1.9 Instrument Panel with CPDS
1.9.4 Function of the CPDS
EC135 Classic 
B1 
Training Manual
01 – 60Iss. August 2018For instruction only
1.9.4 Function of the CPDS
The CAD and VEMD are powered by two independent power supplies 
each. Their respective circuits are protected by two circuit breakers 
each. As both are connected to ESSENTIAL busbars 1 and 2, their 
operational integrity is ensured if one of the busbars should fail.
Switch-on Sequence (Power up) 
The CPDS is activated as soon as the aircraft’s electrical system is 
energized on the ground. An internal self-test and an external self–test 
are run to establish the functional integrity of the CPDS:
While the internal self-test is running, the message TEST IN 
PROGRESS will be displayed on the CAD / VEMD and the soft– and 
hardware is checked. 
After the internal self test has passed, the external self test is performed. 
While the presence of the following parameters is verified the message 
EXTERNAL SELF TEST IN PROGRESS will be displayed on the CAD 
/ VEMD.
SyS I MISC SyS II
ENG CHIP CT TRGB CHP CT ENG CHIP CT
ENG OF CT XMSN CHP CT ENG OF CT
F FILT CT XMSN OT CT F FILT CT
During the external test, the wiring of certain sensors is checked with 
a continuity test (CT). If a failure occurs, the respective sensor is 
displayed on the CAD as a caution with CT as a supplement.
After the external self–test the functional integrity of the peripheral 
assemblies is tested (INP–Test; INP=Input). After the test has run, the 
following cautions will be displayed on the CAD:
SyS I MISC SyS II
ENG FAIL+ F PUMP AFT** ENG FAIL+
ENG OIL P+ F PUMP FWD** ENG OIL P+
FADEC FAIL* EPU DOOR FADEC FAIL*
FUEL PRESS+ BAT DISCON FUEL PRESS+
HYD PRESS+ EXT POWER HYD PRESS+
XMSN OIL P+ XMSN OIL P+
GEN DISCON+ GEN DISCON+
INVERTER*** INVERTER***
PITOT HTR PITOT HTR
FLI FAIL* FLI FAIL*
* only when the FADEC is switched off 
** only when the fuel pumps are switched off 
*** only if the respective system is installed 
+ only these cautions trigger the INP FAIL, if they are not active during 
the test. 
If an error occurs during the test, INP FAIL will appear at the bottom 
edge of column MISC and a yellow bar above and below the respective 
caution will flash. The corresponding caution will appear on the CAD. 
After 8 seconds, the ACK NEEDED prompt is displayed on the upper 
VEMD screen.
In case of a malfunction the respective caution will flash with a yellow 
bar, above and below. This message has to be acknowledged by the 
CDS / AUDIO RES or the select button.
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EC135 Classic 
B1 
Training Manual
01 – 61Iss. August 2018For instruction only
Functional Schematic CPDS
01 – General Information
1.9.4 Function of the CPDS
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.5 Test Pattern
EC135 Classic 
B1 
Training Manual
01 – 62Iss. August 2018For instruction only
1.9.5 Test Pattern
If the switch TEST CDS/WARN UNIT is set to position CDS, a test 
pattern appears with Cyclic Redundant Code (CRC), part number and 
configuration file number. 
Cyclic Redundant Code 
Check sum for the configuration file deviations (manufacturer only). 
Part Number 
Last two digits of the part number identify the software version. 
Example: 
B19030GB10 corresponds to software version V2010.
For the EC135 P3/T3 the software version V2012 is required.
Configuration File 
All software versions are delivered witha basic configuration file. 
Necessary changes (e.g. after installation of optional equipment) 
might require the upload of a customized configuration file delivered 
by Airbus Helicopters. 
Example: 
Customized configuration files L316M30S0001 
♦ NOTE The CPDS description shows the latest standards. 
Major changes with part numbers and serial 
numbers are shown in an overview page at the end 
of the CPDS description. 
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B1 
Training Manual
01 – 63Iss. August 2018For instruction only
Test Pattern - Example Software Version V2010
01 – General Information
1.9.5 Test Pattern
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Training Manual
01 – 64Iss. August 2018For instruction only
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01 – General Information
1.9.5 Test Pattern
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EC135 Classic 
B1 
Training Manual
01 – 65Iss. August 2018For instruction only
CPDS-Architekture for N1 (∆N1), TOT, TQ
01 – General Information
1.9.5 Test Pattern
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1.9 Instrument Panel with CPDS
1.9.6 CPDS Modes
EC135 Classic 
B1 
Training Manual
01 – 66Iss. August 2018For instruction only
1.9.6 CPDS Modes
General 
The following modes are available: 
Flight Status 
 – CAU / FUEL (Caution and fuel page) 
 – FLI (First Limit Indicator) 
 – ELEC / VEH (Electrical and vehicle parameters) 
 – System Status 
 – Inflight Engine Power Check (Trend monitoring) 
 – Caution Fuel Fail 
 – CAU Backup 
Ground Status (Engines Shut Down) 
In addition to the Flight Status the following modes are available: 
 – Flight Report 
 – Maintenance Menu 
 – Configuration (A/C Config Page)
Status of the CPDS
The CPDS distinguishes between GROUND and FLIGHT status 
according to the following parameters:
GROUND Status:
 – N1 RPM engine 1 and engine 2 < 50 %
 – XMSN oil pressure < 1 bar
FLIGHT Status:
 – N1 RPM engine 1 or engine 2 > 50 %
 – XMSN oil pressure > 1 bar
 – collective lever position (CLP) > 28.5 % (Turbomeca) or 
17 % (Pratt&Whitney).
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Training Manual
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01 – General Information
1.9.6 CPDS Modes
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1.9 Instrument Panel with CPDS
1.9.7 CAUTION / FUEL – Page
EC135 Classic 
B1 
Training Manual
01 – 68Iss. August 2018For instruction only
1.9.7 CAUTION / FUEL – Page
The CAUTION / FUEL page is displayed automatically on the CAD.
The fuel quantity parameters are displayed only on the CAD and are 
no longer available if the CAD fails. The units of measurement on this 
page can be changed in the configuration mode (A/C CONFIG page).
The cautions inform the crew of defects in onboard systems. They 
appear in yellow characters in the three columns of the upper half of 
the CAD. The columns are divided as follows: 
 – left column: messages relating to eng. 1 and system 1 
 – center column: messages relating to non–redundant systems 
 – right column: messages relating to eng. 2 and system 2
Cautions are listed in the order of their importance. If there is not 
enough room on the page to display all the cautions, e.g., “1 of 2” 
will appear at the top of the center column to indicate the presence 
of a second page with cautions. This page can be accessed with the 
SCROLL key, but there will be an automatic return to page 1 after 15 
seconds. 
When a new caution appears, all the acknowledged cautions on the 
display will disappear, and a yellow bar will flash above and below the 
new caution. At the same time, the MASTER CAUTION caption next 
to the warning unit will illuminate. 
The crew has to acknowledge the caution(s) by operating the CDS/
AUDIO RES switch on the cyclic stick or the SELECT key on the CAD. 
If the CAD has failed, the SELECT key on the VEMD must be pressed. 
This leads to all cautions being displayed normally in the order of their 
appearance. Also, the MASTER CAUTION caption will extinguish and 
is free for the next error message (caution).
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01 – General Information
1.9.7 CAUTION / FUEL – Page
EC135 Classic 
B1 
Training Manual
01 – 69Iss. August 2018For instruction only
CAD - CAUTION / FUEL Page
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1.9 Instrument Panel with CPDS
1.9.8 CPDS Cautions
EC135 Classic 
B1 
Training Manual
01 – 70Iss. August 2018For instruction only
1.9.8 CPDS Cautions
The following CPDS cautions may be displayed on the CAD or VEMD 
(Example list. Refer to approved rotorcraft FLM).
No. SyS I/II MISC
1. FLI DEGR XMSN CHIP
2. FLI FAIL TRGB CHIP
3. ENG FAIL XMSN OIL T
4. ENG OIL P ROTOR BRK
5. ENG CHIP TRGB CHP CT
6. FADEC FAIL XMSN CHP CT
7. FUEL PRESS F PUMP AFT
8. FUEL FILT F PUMP FWD
9. ENG O FILT F QTY FAIL
10. IDLE F QTY DEGR
11. ENG MANUAL EPU DOOR
12. TWIST GRIP BAT DISCON
13. FUEL VALVE EXT POWER
14. FADEC MINR (PW only) SHED EMER
15. DEGRADE (TM only) XMSN OT CT
16. REDUND (TM only) INP FAIL
17. PRIME PUMP YAW SAS
18. HYD PRESS HTG OVTEMP
19. XMSN OIL P T1 MISCMP (TM only)
20. OVSP (TM only) P0 MISCMP (TM only)
No. SyS I/II MISC
21. GEN OVHT CAU DEGR
22. GEN DISCON CAD FAN
23. INVERTER VEMD FAN
24. BUSTIE OPN CPDS OVHT
25. STARTER FUEL (SW 2001 B and up)
26. ENG CHP CT
27. ENG OF CT
28. F FILT CT
29. PITOT HTR
30. F VALVE CL
31. ENG EXCEED (T2, T2+, P2, P2+)
♦ NOTE Cautions with the letters CT at the end indicate 
negative continuity test of the respective caution 
circuit only.
♦ NOTE If the CAD and one VEMD screen fail only a degraded 
Caution list is available on the remaining screen 
(see respective FLM).
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EC135 Classic 
B1 
Training Manual
01 – 71Iss. August 2018For instruction only
First Limit Page P1 / T1 (Example TM 2B1)
01 – General Information
1.9.8 CPDS Cautions
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.9 Advisories
EC135 Classic 
B1 
Training Manual
01 – 72Iss. August 2018For instruction only
1.9.9 Advisories
The advisories appear in green characters below the cautions in the 
MISC column and provide with information about the operational 
status and optional equipment. 
In certain cases, instead of being displayed on the first page, the 
advisories may be displayed on the second page. If a new caution 
appears, the advisories will disappear until the caution has been 
acknowledged. The green advisories appear initially in the lower part 
of the display fields and then form a column, one after another, under 
the cautions. 
The following advisories are possible (depending on optional 
equipment):
BLEED AIR Bleed air supply has been activated
AIR COND Air conditioning system is active
HOOK UNLD No load on load hook
S/L LIGHT Search and landing light is active
S/L L RETR Search and landing light is fully retracted
IFCO IFCO filter is active
IR ON The IR-filter of the SX 16 is activeSAND FILT Sand filter is active
AUX F XFER Auxiliary tank fuel valve open
TRAIN ARM Training mode is active (P2/T2, P2+/T2+, P3/T3)
PITOT HTR If Pitot Static Heating Sytem is switched on (SW 2003)
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01 – General Information
1.9.9 Advisories
EC135 Classic 
B1 
Training Manual
01 – 73Iss. August 2018For instruction only
First Limit Page P1 / T1 (Example TM 2B1)
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.10 First Limit Page (FLI) P1 / T1
EC135 Classic 
B1 
Training Manual
01 – 74Iss. August 2018For instruction only
1.9.10 First Limit Page (FLI) P1 / T1
The FLI page is displayed on the upper VEMD screen. It contains the 
following data: 
 – FLI zone for TOT, N1 (∆1 with T1), TRQ 
 – mast moment indication 
 – message zone 
 – high information zone 
 – low information zone
Mast Moment Indicator 
The mast moment indicator indicates the bending moment of the main 
rotor. When entering the yellow range (50 % MM) a yellow line appears 
under the letters MM. When entering the red range (66 % MM) the line 
reverts to red, the LIMIT symbol and the warning GONG come on. 
The time of exceedance and the maximum value (last flight and 
accumulation) can be displayed in the maintenance mode. 
♦ NOTE A logbook entry and maintenance action is required 
if the red region has been entered. Periodical 
maintenance action is required if a helicopter is 
operated without or with a defective mast moment 
system. 
Message Zone 
The message zone displays messages concerning failures and 
detected overlimits that are either not visible on the current display 
page or require action by the crew e.g. to switch off a screen. 
The following list shows the messages in the order of their priority: 
 – LANE 1 FAILED . . . . . . . . . . PRESS OFF 1 
 – LANE 2 FAILED . . . . . . . . . . PRESS OFF 2 
 – CAD FAILED . . . . . . . . . . . . PRESS OFF 
 – CAUTION DETECTED 
 – VEH PARAM OVER LIMIT 
 – GEN PARAM OVER LIMIT (normal during engine starting)
 – DC VOLT PARAM OVER LIMIT 
 – CROSSTALK FAILED . . . . . PRESS OFF 2 
 – VEMD BRIGHTNESS CONTROL FAILED 
 – CAD BRIGHTNESS CONTROL FAILED
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01 – General Information
1.9.10 First Limit Page (FLI) P1 / T1
EC135 Classic 
B1 
Training Manual
01 – 75Iss. August 2018For instruction only
First Limit Page P1 / T1 (Example TM 2B1)
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.11 FLI ZONE P1 / T1
EC135 Classic 
B1 
Training Manual
01 – 76Iss. August 2018For instruction only
1.9.11 FLI ZONE P1 / T1
The engine 1 and 2 parameters are generated by the two FADEC 
systems and are displayed on the screen as numerical values with the 
corresponding measurement units. 
In addition, the parameter that is nearest to its limit is displayed as 
an analog pointer on a scale (named First Limit Indication) and the 
numerical value of the parameter indicated by the pointer is marked 
by a white rectangle. 
If a parameter fails, it is displayed in yellow characters without its 
associated numeric value.
1.9.12 Limit Light / Counter
AEO above MCP 
Five seconds before the 5 min power (AEO) time limit is reached the 
red box, the limit light and the counter appear and the box flashes. 
When the time limit is expired, the red box is fixed. 
OEI above MCP 
When entering the 2.5 min power (OEI) the counter appears 
immediately. The limit light and the red box come on 5 sec before the 
time limit is reached. The box flashes and becomes fixed when the 
time limit is expired. 
When the pilot leaves the limited range the limit box and the audio 
tone remain active for another 5 sec.
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EC135 Classic 
B1 
Training Manual
01 – 77Iss. August 2018For instruction only
FLI-Marking Symbology on Analog Display P1 / T1 (Example TM 2B1)
01 – General Information
1.9.12 Limit Light / Counter
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.13 First Limit Page (FLI) P2 / T2 and P2+ / T2+
EC135 Classic 
B1 
Training Manual
01 – 78Iss. August 2018For instruction only
1.9.13 First Limit Page (FLI) P2 / T2 and P2+ / T2+
The FLI page is displayed on the upper VEMD screen. It contains the 
following data: 
 – FLI zone for TOT, N1 (∆1 with TM), TRQ 
 – mast moment indication 
 – message zone 
 – high information zone 
 – low information zone 
Mast Moment Indicator 
The mastm oment indicator indicates the bending moment of the main 
rotor. When entering the yellow range (50 % MM) a yellow line appears 
under the letters MM. When entering the red range (66 % MM) the line 
reverts to red, the LIMIT symbol and the warning GONG come on. 
The time of exceedance and the maximum value (last flight and 
accumulation) can be displayed in the maintenance mode. 
♦ NOTE A logbook entry and maintenance action is required 
if the red region has been entered. Periodical 
maintenance action is required if a helicopter is 
operated without or with a defective mast moment 
system. 
Message Zone 
The message zone displays messages concerning failures and 
detected overlimits that are either not visible on the current display 
page or require action by the crew e.g. to switch off a screen. 
The following list shows the messages in the order of their priority: 
 – LANE 1 FAILED . . . . . . . . . . PRESS OFF1 
 – LANE 2 FAILED . . . . . . . . . . PRESS OFF2 
 – CAD FAILED . . . . . . . . . . . . .PRESS OFF
 – CAUTION DETECTED 
 – VEH PARAM OVER LIMIT
 – GEN PARAM OVER LIMIT (normal during engine starting) 
 – DC VOLT PARAM OVER LIMIT 
 – CROSSTALK FAILED . . . . . PRESS OFF2 
 – VEMD BRIGHTNESS CONTROL FAILED 
 – CAD BRIGHTNESS CONTROL FAILED
♦ NOTE Since EC135 T2+ / P2+ the message GEN PARAM 
OVER LIMIT is suppressed on ground with one 
engine in start mode.
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EC135 Classic 
B1 
Training Manual
01 – 79Iss. August 2018For instruction only
First Limit Page T2 / T2+, P2 / P2+ highly similar
01 – General Information
1.9.13 First Limit Page (FLI) P2 / T2 and P2+ / T2+
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.14 High Information Zone
EC135 Classic 
B1 
Training Manual
01 – 80Iss. August 2018For instruction only
1.9.14 High Information Zone
The high information zone is located on the FLI screen at the upper 
left corner for system1 and the upper right corner for system 2. It 
indicates: 
 – ENG FAIL 
 – FADEC FAIL 
 – ENG MANU 
 – IDLE 
 – TRAIN 
 – TRAIN IDLE 
Low Information Zone 
The low information zone is located on the FLI screen at the lower 
left corner for system 1 and the lower right corner for system 2. It 
indicates: 
FLI DEGR in case one of the three engine parameter becomes invalid 
FLI FAIL in case invalidity of more than one parameter. 
♦ NOTE In case of FLI DEGR the respective FLI needle may 
be driven by a not limiting parameter. In case of 
FLI FAIL the respective needle is removed. Both 
indications are also displayed as a caution on the 
CAD. 
FLI / Parameter Zone 
The FLI / Parameter zone indicates the 
 – engine torque (TRQ) 
 – turbine outlettemperature (TOT) 
 – gas generator turbine speed (N1) for engine 1 (left) and for 
engine 2 (right).
The parameters are shown in numerical values. In addition the 
parameter which is closest to its limit drives the analog pointer of the 
scale (i.e. First Limit Indication). The limiting parameter is marked 
with a white rectangle; and underlined yellow if in the caution range. 
Underlining changes to blinking red if a limit is reached. 
If a parameter fails, it is displayed in yellow without its numerical value. 
(TM only). In case of N1 becomes the limiting parameter the FLI 
needles are indicating the Delta N1. Thereby the real N1 is calculated 
by air pressure and temperature in order to receive a N1 limit for this 
density condition. Delta N1 is the margin between the calculated and 
the actual N1.
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EC135 Classic 
B1 
Training Manual
01 – 81Iss. August 2018For instruction only
First Limit Page P3
01 – General Information
1.9.14 High Information Zone
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1.9 Instrument Panel with CPDS
1.9.15 AEO Power Bands
EC135 Classic 
B1 
Training Manual
01 – 82Iss. August 2018For instruction only
1.9.15 AEO Power Bands
When entering the solid yellow range the max. continuous power band 
is left and the H/C is operating in the 5’ take-off power band.
1.9.16 OEI Power Bands 
If a OEI situation is detected the 30’’ power topping function is the 
default setting. Thus the 30’’power band is available (small red triangle 
in the FLI pointing at the 30’’ power limit; indication OEI HI on the 
right side in the FLI, respective digital value(s) red blinking underlined 
when band is entered). 
If desired, the pilot can select the 2’ power topping function (selector 
switch on the collective). The small red triangle appears at the 2’ power 
limit and the indication OEI LO is shown in the FLI (respective digital 
value(s) yellow steady underlined when band is entered). 
1.9.17 Limit Light 
The limit light and counter is shown in the right center part of the FLI 
screen.Whenever a FLI limit is exceeded (incl. mastmoment) the limit 
light in a red box becomes visible in combination with an audio warning 
(gong). Furthermore, a pre--warning of a parameter exceedance has 
been integrated. 
♦ NOTE A logbook entry is required whenever OEI maximum 
continuous power has been exceeded. 
1.9.18 Countdown Timer 
AEO above MCP 
5’ countdown timer 
Five seconds before the time limit is reached, the red flashing box, the 
limit symbol and the counter appear.When the time limit is expired, the 
red box is permanently visible. 
OEI above MCP 
2.5’ countdown timer (P2 only) 
Always becomes active if the power is above OEI MCP and within the 
2’ power band without entering the 30’’ power band. In this case the 2’ 
power band is extended for 30’’ (derated 30’’ power). 
2.5’ countdown timer (T2 only) 
The 2.5’ countdown timer is always active if the power is above the 
MCP. 
2’ countdown timer (P2 only) 
Becomes active if the power is above OEI MCP and within the 2’ power 
band and there has been an uninterrupted usage of the 30’’ power 
band for more than 5 seconds during continued operation above OEI 
MCP. 
30’’ countdown timer 
Becomes active if the power is above OEI MCP and within the 30’’ 
power band. 
Only one counter is presented to the pilot at a given time, providing 
the remaining time within the power band he is using. 
Internally, the times in the 2’ and 30’’ power band are accumulated.
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EC135 Classic 
B1 
Training Manual
01 – 83Iss. August 2018For instruction only
FLI - Marking Symbology on Analog Display (Example T2/T2+, P2/P2+, T3/P3 highly similar)
01 – General Information
1.9.18 Countdown Timer 
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.19 ENG EXCEED Caution
EC135 Classic 
B1 
Training Manual
01 – 84Iss. August 2018For instruction only
1.9.19 ENG EXCEED Caution
EC135 T2 
The ENG EXCEED caution appears on ground under the following 
conditions: 
Exceedance of a single time excursion in a OEI power band (2’ or 
30’’). 
Significant exceedance of the 30’’ power band with reaching and 
maintaining the following values for more than 5 seconds: 136 % 
Tq,4.8 % Δ n1 (only possible in case of topping function failure) or 
1024 °C TOT. 
If the accumulated time limit of one of the engine parameter does not 
allow a triple complete usage of the emergency power time any more 
(90 sec. within the 30” power band and 6 min. within the 2’ power 
band). 
EC135 P2 
The ENG EXCEED caution appears in flight under the following 
conditions: 
Significant exceedance of the 30’’ power band with reaching and 
maintaining the following values for more than 5 seconds: 133 % Tq, 
104.3 % n1 or 990 °C TOT (only possible in case of topping function 
failure). 
Exceedance of a single time excursion in an OEI power band (2’ or 
30’’). In the latest FADEC software version, the caution disappears 
when the respective power band is left. 
The total allowed time in an OEI power band is expired. 
The ENG EXCEED caution appears on ground under the following 
conditions: 
If due to the cumulated total time in one or both OEI power bands any 
engine parameter does not allow a minimum of 3 pulls with full single 
excursion time i.e. if the remaining total time is less than 90 s and 
360 s for the 30’’ and 2’ OEI power band respectively. 
♦ NOTE The ENG EXCEED caution is stored in the FADEC 
and appears at the next FADEC start up. 
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EC135 Classic 
B1 
Training Manual
01 – 85Iss. August 2018For instruction only
01 – General Information
1.9.20 Warnings 
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.19 ENG EXCEED Caution
EC135 Classic 
B1 
Training Manual
01 – 86Iss. August 2018For instruction only
1.9.20 Warnings 
LIMIT symbol with box and audio warning GONG 
Two different limit conditions for the activation of the LIMIT light with 
box and the audio GONG are possible: 
 – The LIMIT symbol with box activation due to OEI / AEO time 
limit exceedance. 
 – As soon as only 5 s of the allowed time in either power 
band (5’, 2’ or 30’’) are left, a LIMIT symbol with a blinking 
red box appears. This provides the pilot with a precaution 
that the allowed time within the power band is about to 
expire. If the allowed single time excursion is consumed 
(counter reaches 0), the box stops blinking, turns into 
steady state. The audio GONG is triggered. 
 – The LIMIT symbol with box and activation due to limiting 
value exceedance. 
 – Exceedance of one of the engine or H/C limiting parameters 
(30’’ power, 5’ take-off power, mastmoment) triggers the 
LIMIT symbol with the box in the steady state together 
with the audio signal at once. 
♦ NOTE Whenever red limit is exceeded is evident, a logbook 
entry and maintenance action is required.
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01 – General Information
1.9.20 Warnings 
EC135 Classic 
B1 
Training Manual
01 – 87Iss. August 2018For instruction only
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01 – General Information1.9 Instrument Panel with CPDS
1.9.21 Electrical and Vehicle Parameters (ELEC/VEH)
EC135 Classic 
B1 
Training Manual
01 – 88Iss. August 2018For instruction only
1.9.21 Electrical and Vehicle Parameters (ELEC/
VEH)
General 
The page for the electrical and vehicle parameters is displayed 
automatically on the lower VEMD screen. The units for the various 
parameters on this page can be selected in the configuration mode. 
The following parameters can be displayed: 
 – outside air temperature OAT 
 – load on cargo hook, cable length of external hoist, ice warning 
system (options)
 – voltage and current 
 – oil pressure and oil temperature of the engines and of the 
main transmission.
 – velocity never exceed VNE (P3 / T3 only)
The oil pressure and temperature indication consists of a vertical bar 
with upper and lower limits for each parameter and a numeric display 
with an associated unit of measurement. 
Some parameters, displayed on the ELEC/VEH fields can be varied.
By using the SELECT key, a white box is brought up highlighting the 
Optionals field. Further action on the key toggles the box to the GEN–
Field which can also be varied. Changes are done by using the “+” 
and “-” keys, if the change should be kept, the ENTER key has to be 
pressed, otherwise the indication will switch back to the default value. 
In case a value is invalid, “XXX” is displayed in yellow characters.
Outside Air Temperature (OAT) 
The sensor for the OAT can be found on the RH lower shell, close to 
the forward cross tube, and will provide the respective information to 
the CPDS. 
Ice Rate (LWC) / Cargo Hook HOOK / Cable Length 
CABLE 
LWC (Liquid Water Content), HOOK and CABLE share the same 
indication field. Depending on the configuration it is possible to toggle 
between the indication by using the “+” or “-” key. 
Voltage and Current 
The voltage and current indication shows the voltage which supplies 
the essential bus bars. Additionally the generator current and the 
battery current is monitored in the background. 
Oil Pressure and Temperatures 
Within the vehicle field, oil pressures and temperatures are indicated. 
They are grouped to systems. The indications consist of vertical 
bar graphs with upper and lower limits. The numerical value of a 
parameter is permanently displayed. If the respective parameter 
enters the caution range, it is additionally underlined yellow. When a 
limit is reached the underlining changes to flashing red. 
♦ NOTE In addition to the flashing underline the limit bar 
graph will grow. 
♦ NOTE No audio warning is triggered.
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EC135 Classic 
B1 
Training Manual
01 – 89Iss. August 2018For instruction only
Electrical and Vehicle Parameters
01 – General Information
1.9.21 Electrical and Vehicle Parameters (ELEC/VEH)
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.22 VNE
EC135 Classic 
B1 
Training Manual
01 – 90Iss. August 2018For instruction only
1.9.22 VNE
In the P3 / T3 helicopters the CPDS shall continuously calculate the 
never exceed speed VNE. 
The calculated VNE is a funtion of gross aircraft weight, pressure 
altitude and OAT. The calculation can be influenced by the selection 
of the current gross weight. The three possible choices are:
 – Weight > 2700 kg 
 – Weight < 2400 kg 
 – 2400 kg < Weight > 2700 kg
Selection 
On the VEH / ELEC Page the weight can be selected by pushing 
the SELECT key until the respective field is reached. From there 
on the selection is done via the + / - keys. Pushing SELECT again 
acknowledges the choice. Now VNE will be displayed with an arrow 
and an airspeed in kts. The pointer upwards means > 2700 kg. The 
pointer down means < 2400 kg while the pointer to the right stands 
for in between 2400 kg and 2700 kg. The selection can be changed 
in flight as fuel will be consumed and the gross mass will be reduced.
ALERT
If IAS is higher than the calculated VNE an alert will appear on the FLI. 
The Limit Box will appear together with an audio alert. In addition VNE 
will be displayed with a red blinking underline below the Limit box. On 
the VEH / ELEC page VNE will be underlined by a blinking red line. 
Emergency 
In case of OEI condition the VNE is the same than in AEO operation 
but never greater than 110 kts. 
In case of steady autorotation (AR) the VNE is the same than in AEO 
operation but never greater than 90kts. 
Malfunction 
In case of a loss of IAS information (e.g. loss of ADC) the caution IAS 
will appear on the VEH / ELEC Page below the VNE. If the calculated 
airspeed will be exceeded the VNE Warning will no longer appear. 
The VNE calculation is not affected and will still show the maximum 
allowed airspeed.
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EC135 Classic 
B1 
Training Manual
01 – 91Iss. August 2018For instruction only
ELEC/VEH - Bar Graph Display
01 – General Information
1.9.22 VNE
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.23 SYSTEM STATUS Page
EC135 Classic 
B1 
Training Manual
01 – 92Iss. August 2018For instruction only
1.9.23 SySTEM STATUS Page
General 
The SYSTEM STATUS page is displayed on the lower VEMD screen 
and is called up by pushing the SCROLL key. FADEC data from the 
engines are displayed. 
Depressing the SCROLL key again switches to the Inflight Engine 
Power Check pages. Return to the normal page ELEC / VEH is done 
by pressing SCROLL again or directly by RESET. 
SySTEM STATUS Page
The MSG and FAIL lines display messages and error codes. These 
lines can be accessed individually with the SELECT key. When a 
line is selected, the + or - key can be pressed to continuously cycle 
the current messages and error codes for FADEC 1 and FADEC 2 
simultaneously in their respective order. 
The values of the parameters of FADEC 1 and FADEC 2 are displayed 
below the MSG and FAIL lines and are continuously updated.
In the lower part a subsystem information is shown. Data from FCDS 1 
/ AFCS / FCDS 2 are displayed (failure messages). 
Message Line 
In the Message line various engine states are indicated: 
 – FLIGHT 
 – IDLE 
 – STOP 
 – FADEC 
 – REDUND (TM) 
 – DEGRADE (TM) 
 – FAIL 
 – FADEC MINR (PW) 
Fail Line 
Below the Message Line, the respective malfunctions will be displayed. 
For further information the respective engine maintenance manual 
has to be consulted. 
E.g.: 
 – T1 
 – P0 
 – CLP
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EC135 Classic 
B1 
Training Manual
01 – 93Iss. August 2018For instruction only
SySTEM STATUS Page
01 – General Information
1.9.23 SYSTEM STATUS Page
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EC135 Classic 
B1 
Training Manual
01 – 94Iss. August 2018For instruction only
System Status Page (TM)
01 – General Information
1.9.23 SYSTEM STATUS Page
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EC135 Classic 
B1 
Training Manual
01 – 95Iss. August 2018For instruction only
System Status Page (PW)
01 – General Information
1.9.23 SYSTEM STATUS Page
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EC135 Classic 
B1 
Training Manual
01 – 96Iss. August 2018For instruction only
System Status Page (PW)
01 – General Information
1.9.23SYSTEM STATUS Page
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EC135 Classic 
B1 
Training Manual
01 – 97Iss. August 2018For instruction only
INTENTIONALLy LEFT BLANK
01 – General Information
1.9.23 SYSTEM STATUS Page
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.24 Inflight Engine Power Check Page
EC135 Classic 
B1 
Training Manual
01 – 98Iss. August 2018For instruction only
1.9.24 Inflight Engine Power Check Page
This option allows to perform periodical engine power checks very 
comfortably. Performing a ground power check, one engine is set to 
idle and the other engine has to be capable of developing sufficient 
power without exceeding the given limits. In flight, the power check 
is carried out in twin engine level flight. If all conditions are fulfilled, 
the power check data are stored automatically. The conditions for the 
power check are shown at the display. 
Pressing SCROLL at the VEMD a second time enters the Inflight 
Engine Power Check page. Information is given how to obtain the 
correct test conditions (e.g. “reduce generator power”, “perform level 
flight > 65 KIAS”).
If the conditions for the power check are fulfilled, the button ENTER 
has to be pressed to start the power check. During the check a loading 
bar will show the progress. When the check has been accomplished, 
the margin will be displayed and the respective engine parameters 
are stored. 
The CPDS will calculate a maximum permissible value (TOT for 
PW; N1 for TM) based on the current environmental conditions. The 
difference between the calculated and the determined values is called 
margin. If the actual value is below the calculated one, the margin is 
shown positive. Should the engine no longer be capable of developing 
sufficient power, the margin is underlined yellow and negative. 
Stored data can be accessed again in the maintenance mode selection 
INFLIGHT EPC RESULT. 
The Inflight Engine Power Check Page is standard from software 
version 2005 and following versions. From software version 2003 until 
version 2005 it was optional. 
♦ NOTE For operation of the Inflight Engine Power Check 
see MSM and Flight Manual chapter 5. Nevertheless 
the results must be recorded in the helicopter’s 
documentation. 
♦ NOTE An Inflight Power Check is established in addition to 
the Ground Power Check. This flight check will mainly 
be used to establish a power trend monitoring, e. g. 
every 100 fh. It is no alternative to the Ground Power 
Check. Refer to the approved FLM.
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EC135 Classic 
B1 
Training Manual
01 – 99Iss. August 2018For instruction only
Inflight Engine Power Check Page
01 – General Information
1.9.24 Inflight Engine Power Check Page
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.25 EPC Fail Page
EC135 Classic 
B1 
Training Manual
01 – 100Iss. August 2018For instruction only
1.9.25 EPC Fail Page
The following parameters are required for the EPC: 
 – TRQ 
 – TOT 
 – N1 
 – PO 
 – TO 
If one of the parameters is not valid, the EPC cannot be performed. 
In this case the EPC Fail Page will appear and the invalid parameters 
are displayed.
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EC135 Classic 
B1 
Training Manual
01 – 101Iss. August 2018For instruction only
Inflight Engine Power Check Fail Page
01 – General Information
1.9.25 EPC Fail Page
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.26 CPDS Switch Over Functions
EC135 Classic 
B1 
Training Manual
01 – 102Iss. August 2018For instruction only
1.9.26 CPDS Switch Over Functions
General 
Depending upon how many screens of the CPDS are available, 
the pages on the CAD and VEMD can be switched manually and 
automatically. 
Three operating modes of the CPDS are possible: 
 – normal mode (3 screens available) 
 – derivative mode (2 screens available) 
 – backup mode (1 screen available). 
Normal Mode 
In the normal mode all three screens are operative. All pages are 
available in a variety of combinations, except the CAUTION / BACKUP 
and CAUTION / FUEL FAIL page. 
The pages can be selected manually via the SCROLL key. 
If the RESET key on the VEMD is pressed, the standard pages will 
reappear on the screen.
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EC135 Classic 
B1 
Training Manual
01 – 103Iss. August 2018For instruction only
CPDS - Normal Mode
01 – General Information
1.9.26 CPDS Switch Over Functions
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.27 Derivative Mode with one VEMD Lane off
EC135 Classic 
B1 
Training Manual
01 – 104Iss. August 2018For instruction only
1.9.27 Derivative Mode with one VEMD Lane off
If a screen or a processing module fails, the part of the VEMD that is 
still functioning will still be able to present the most important data.
If one of the VEMD screens fails in flight, the FLI page will continue 
to be displayed on the intact VEMD screen, the CAD will display the 
CAUTION / FUEL page (degraded caution indication), and the ELEC 
/ VEH page will be available when the SCROLL key is used. The 
SYSTEM STATUS page can also be selected. 
The FLI page will automatically switch to the FLIGHT REPORT page 
only if both engine RPM drops below 50 % and the oil pressure in the 
main transmission is less than 1 bar (GROUND STATUS).
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EC135 Classic 
B1 
Training Manual
01 – 105Iss. August 2018For instruction only
Derivative Mode with one VEMD Lane off
01 – General Information
1.9.27 Derivative Mode with one VEMD Lane off
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.28 Derivative Mode with CAD off
EC135 Classic 
B1 
Training Manual
01 – 106Iss. August 2018For instruction only
1.9.28 Derivative Mode with CAD off
The CAUTION / FUEL FAIL page will appear automatically on the 
lower VEMD screen.
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EC135 Classic 
B1 
Training Manual
01 – 107Iss. August 2018For instruction only
Derivative Mode with CAD off
01 – General Information
1.9.28 Derivative Mode with CAD off
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.29 CAUTION / FUEL FAIL Page
EC135 Classic 
B1 
Training Manual
01 – 108Iss. August 2018For instruction only
1.9.29 CAUTION / FUEL FAIL Page
The CAUTION / FUEL FAIL page is displayed automatically on the 
lower VEMD screen if the CAD has failed. 
At the same time, the ∆N1 information in the FLI (Turbomeca Versions 
only) is lost. The FLI DEGR caution is triggered in the FLI and in the 
CAUTION / FUEL FAIL page in the system I and system II column. 
Since the fuel information is only availableon the CAD the CAUTION 
/ FUEL FAIL page shows an empty yellow box where normally the 
fuel quantity is displayed. Furthermore, only a degraded caution list is 
available, indicated by CAU DEGR in the miscellaneous field.
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EC135 Classic 
B1 
Training Manual
01 – 109Iss. August 2018For instruction only
CAUTION / FUEL Fail Page (Example TM)
01 – General Information
1.9.29 CAUTION / FUEL FAIL Page
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.30 Backup Mode with CAD and one VEMD Lanes off 
EC135 Classic 
B1 
Training Manual
01 – 110Iss. August 2018For instruction only
1.9.30 Backup Mode with CAD and one VEMD 
Lanes off 
If one of the VEMD screens fails in flight, the FLI page will be presented 
on the intact VEMD screen. 
With the SCROLL button the CAUTION / FUEL FAIL page and the 
ELEC / VEH page can be selected.
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EC135 Classic 
B1 
Training Manual
01 – 111Iss. August 2018For instruction only
Backup Mode with CAD and one VEMD Lanes off
01 – General Information
1.9.30 Backup Mode with CAD and one VEMD Lanes off 
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.31 Backup Mode with both VEMD Lanes off 
EC135 Classic 
B1 
Training Manual
01 – 112Iss. August 2018For instruction only
1.9.31 Backup Mode with both VEMD Lanes off 
If only the CAD is still operative, the CAUTION / BACKUP page is 
displayed. 
No other pages are available any more.
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EC135 Classic 
B1 
Training Manual
01 – 113Iss. August 2018For instruction only
Backup Mode with both VEMD Lanes off
01 – General Information
1.9.31 Backup Mode with both VEMD Lanes off 
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.32 CAUTION / BACKUP Page
EC135 Classic 
B1 
Training Manual
01 – 114Iss. August 2018For instruction only
1.9.32 CAUTION / BACKUP Page
The CAUTION / BACKUP page is displayed on the CAD only if the 
VEMD fails completely. The following data are displayed: 
 – Cautions (degraded indication only) 
 – Advisories 
 – Numeric readout of fuel contents in main and supply tanks.
 – Engine 1 and 2 torque on analog scale with numeric limiting 
values. 
If a torque channel fails, the associated pointer and numerical readout 
are faded out; the scale and TRQ parameter turn yellow. 
As this page represents an emergency operating mode, no other 
pages or data can be presented.
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EC135 Classic 
B1 
Training Manual
01 – 115Iss. August 2018For instruction only
CAUTION / BACKUP Page
01 – General Information
1.9.32 CAUTION / BACKUP Page
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.33 FLIGHT REPORT Page
EC135 Classic 
B1 
Training Manual
01 – 116Iss. August 2018For instruction only
1.9.33 FLIGHT REPORT Page
The VEMD 2 will automatically switch to the FLIGHT REPORT page 
only if both engine N1 RPM drop below 50 % and the oil pressure in 
the main transmission is less than 1 bar (GROUND STATUS). 
The page contains the following data: 
 – flight number and flight duration 
 – gas generator turbine cycles 
 – power turbine cycles 
 – impeller cycles (Pratt & Whitney only)
 – mast moment overlimit times (SW 2003 and up) 
 – failure indication of the affected system (SW 2003 and up).
Mast Moment overlimits are only shown if they occured during this 
flight. 
Failure messages like “CPDS” “FCDS” “AFCS” are only displayed if 
respective failures occured during this flight.
Returning from this page to the nominal page is possible only by 
operating the RESET key.
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EC135 Classic 
B1 
Training Manual
01 – 117Iss. August 2018For instruction only
Flight Report Page (Example PW)
01 – General Information
1.9.33 FLIGHT REPORT Page
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.34 Maintenance Menu 
EC135 Classic 
B1 
Training Manual
01 – 118Iss. August 2018For instruction only
1.9.34 Maintenance Menu 
The maintenance menu is displayed on the VEMD (upper screen). 
The submenues provide access to flight and failure data. The following 
sub menues are possible: 
 – Flight Report 
 – Failure 
 – Over Limit 
 – Inflight EPC Result 
 – Trans Data 
 – Funct. Times 
 – Data Loading. 
The maintenance mode can only be entered when the CPDS is in 
GROUND STATUS.
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EC135 Classic 
B1 
Training Manual
01 – 119Iss. August 2018For instruction only
Maintenance Menu
01 – General Information
1.9.34 Maintenance Menu 
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.35 Flight Report
EC135 Classic 
B1 
Training Manual
01 – 120Iss. August 2018For instruction only
1.9.35 Flight Report
Flight Report History Page 
The Flight Report History page shows CPDS flight numbers and 
indicates duration of the respective flight. 
Duration counting starts if: 
 – N1 RPM engine 1 or engine 2 > 50 % 
 – XMSN oil pressure is > 1 bar
 – angle of collective lever CLP > 28.5 % (TM) or 17 % (PW). 
The Flight Report History can only be entered when the ground state 
is detected. The page stores the last 32 flights. They are selectable 
with the + / - button. 
♦ NOTE No. 1 of the 32 stored flights is always the latest 
flight.
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EC135 Classic 
B1 
Training Manual
01 – 121Iss. August 2018For instruction only
Flight Report History Page PW
01 – General Information
1.9.35 Flight Report
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.36 Failure
EC135 Classic 
B1 
Training Manual
01 – 122Iss. August 2018For instruction only
1.9.36 Failure
Flight Selection Page 
The Flight Selection page indicates flights on which failures occured. 
It shows the flight numbers and the number of accumulated failures 
during that flight. 
The failure memory contains 256 failures which are organized in a 
circular buffer. 
By pressing the ENTER button the failures of the selected flight will be 
displayed in detail. 
The example shows 10 failures. Pressing ENTER activates a sub 
page giving the information that 8 failures occured at the VEMD and 
2 at the CAD. On this sub–page, the VEMD or CAD can be selected.
By pressing ENTER again, the respective failures are shown. With 
+ / - it is possible to scroll through all failures. A failure code is shown 
in the upperpart of the screen. Sometimes a message “to see param. 
press ENTER” appears at the screen. Then it is possible to get detailed 
information about this specific failure and a further sub–page can be 
entered. Pressing EXIT enables to jump back one sub–page level. 
The SDS contains a list with the respective failure codes. Most of the 
codes are very detailed and manufacturer’s level.
♦ NOTE If power is supplied to the aircraft’s electrical system 
and a failure on ground is detected (e.g. internal / 
external check) the CPDS stores this failure. The 
CPDS uses the next flight number to store those 
failure codes. They can be displayed in the Flight 
Report History page.
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EC135 Classic 
B1 
Training Manual
01 – 123Iss. August 2018For instruction only
Flight Selection Page / Subsystem Selection
01 – General Information
1.9.36 Failure
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.36 Failure
EC135 Classic 
B1 
Training Manual
01 – 124Iss. August 2018For instruction only
1.9.36.1 Overlimit
Overlimit Menu Page 
The Overlimit page shows the last 8 flight numbers. By selecting one 
flight number a new page appears. 
This page shows two ranges (MM > 66 %, MM > 78 %) together with 
the time of exceedance and the maximum reached mast moment.
The lower two lines are indicating the cumulated time for the two 
ranges.
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EC135 Classic 
B1 
Training Manual
01 – 125Iss. August 2018For instruction only
Overlimit Menu Page
01 – General Information
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.37 Inflight Engine Power Check (Inflight EPC)
EC135 Classic 
B1 
Training Manual
01 – 126Iss. August 2018For instruction only
1.9.37 Inflight Engine Power Check (Inflight EPC)
Inflight EPC Result 
The engine power has to be checked due to the regular inspection 
intervals. To simplifiy the procedure an engine power check page was 
created. 
Stored data can be accessed again in the maintenance mode selection 
INFLIGHT EPC RESULT. 
The inflight EPC menu shows the last 8 flights where a power check 
was performed. This enables a trend monitoring by comparing the 
previous results. 
The following data are stored: 
 – engine torque TRQ 
 – engine TOT 
 – N1 
 – altitude in feet 
 – OAT 
 – margin
♦ NOTE The inflight EPC is for trend monitoring only.
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EC135 Classic 
B1 
Training Manual
01 – 127Iss. August 2018For instruction only
INFLIGHT EPC RESULT (Example TM)
01 – General Information
1.9.37 Inflight Engine Power Check (Inflight EPC)
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.38 Transfer Data 
EC135 Classic 
B1 
Training Manual
01 – 128Iss. August 2018For instruction only
1.9.38 Transfer Data 
Transfer Data is used to copy data from one VEMD lane to the other in 
case a configuration difference between the lanes has been indicated.
1.9.39 Functional Times 
The Functional Times page shows the accumulated flight hours and 
function times for the VEMD modules 1 and 2 and the function times 
for the CAD.
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EC135 Classic 
B1 
Training Manual
01 – 129Iss. August 2018For instruction only
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01 – General Information
1.9.39 Functional Times 
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.38 Transfer Data 
EC135 Classic 
B1 
Training Manual
01 – 130Iss. August 2018For instruction only
1.9.39.1 Data Loading 
With Data Loading a customized configuration file can be uploaded 
(e.g. modified caution list).
♦ NOTE With the Avionique Novelle Configuration Tool 
(software, PC, connecting cable to maintenance 
connectors) the customer can upload modified 
configuration files prepared by Airbus Helicopters. 
The current software version remains unchanged, 
only the basic configuration file will be overwritten.
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01 – General Information
1.9.39 Functional Times 
EC135 Classic 
B1 
Training Manual
01 – 131Iss. August 2018For instruction only
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.40 A/C CONFIG Page
EC135 Classic 
B1 
Training Manual
01 – 132Iss. August 2018For instruction only
1.9.40 A/C CONFIG Page
The CONFIG mode can only be entered in GROUND STATUS. The 
VEMD screens must be switched off, the CAD must be switched on 
before entering the A/C CONFIG page. 
The following parameters can be set on the A/C CONFIG page (I = 
installed, N/I = not installed):
 – AUXILIARY FUEL TANK [I], [N/I] 
Setting if an auxiliary tank is installed. If N/I is set the graphic 
display disappears from the page CAU/FUEL and the digital 
value from the page CAU/BACKUP. 
 – BATTERY TEMP. PROBE [I], [N/I] (up to software V2002)
Setting if a temperature sensor for the battery is installed. 
 – ICING RATE SYSTEM [I], [N/I] (from software V2003) 
Setting if an ice detection system is installed. When I is set, 
the display on page ELEC / VEH is the LWC message with a 
triangle pointer (LWC = Liquid Water Content). 
 – SECOND BATTERY [I], [N/I] 
Setting if a second battery is installed.
 – EXTERNAL LOAD [N/I], [HOOK], [CABLE] 
Setting if a cargo hook or an external mounted hoist system 
is installed. Depending on the setting, the display on the page 
ELEC / VEH remains empty, HOOK with the measurement 
unit kg or lb or CABLE with the measurement unit m or ft 
are shown, if associated modification on HOOK / CABLE is 
installed (STC of Manufacturer) 
 – FUEL FLOW WITH SENSOR [I], [N/I] 
Setting if a fuel flow meter is installed. If N/I is set the description 
and numeric value on page CAU/FUEL are hidden. 
 – FUEL UNIT [LITER], [kg or lb], [US GALLON], [IMP. GALLON]
Setting which measurement unit is used to display the 
contents of the fuel tank. Depending on the setting, the 
appropriate measurement unit is shown next to the numeric 
tank displays on the page CAU / FUEL or CAU / BACKUP. 
 – UNIT SYSTEM [SI], [IMPERIAL] 
Setting which unit system is used.
 – ALT. AND SPEED UNIT [FEET], [METER] 
Determines which measurement unit is used. Depending on 
the setting, the appropriate measurement unit is shown next 
to the numeric value on the page ELEC / VEH. 
 – MAST MOMENT [I], [N/I] 
Setting if a mast moment system is installed. When N/I is set, 
the display on the page FLI is not visible.
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01 – General Information
1.9.40 A/C CONFIG Page
EC135 Classic 
B1 
Training Manual
01 – 133Iss. August 2018For instruction only
A/C CONFIG Page
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01 – General Information1.9 Instrument Panel with CPDS
1.9.40 A/C CONFIG Page
EC135 Classic 
B1 
Training Manual
01 – 134Iss. August 2018For instruction only
1.9.40.1 Unit System
The possible settings for parameter UNIT SYSTEM are SI and 
IMPERIAL. The table lists the units for the setting SI and IMPERIAL:
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EC135 Classic 
B1 
Training Manual
01 – 135Iss. August 2018For instruction only
Unit System
01 – General Information
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.41 CPDS Software Versions Overview
EC135 Classic 
B1 
Training Manual
01 – 136Iss. August 2018For instruction only
1.9.41 CPDS Software Versions Overview
The software version can be identified with the last two digits in the 
part number (e.g. part number ...02 corresponds software version 
V1999). 
The major features of the different CPDS software versions and some 
changes depending on H/C serial number are shown in the following 
listings: 
V1999 (Part Number ...02) 
Basic Version for EC135 T1 (TM 2B1 engines) and P1 (PW 206B 
engines). 
Mast moment indication > 50 % yellow range, > 78 % red range. The 
supply tank volumes reverts from blue into yellow if no transfer is 
provided or if the supply tanks volumes are below a certain value.
V2000A (Part Number: ...03) 
Modified mast moment indication: 
> 50 % MM underlined yellow 
> 66 % MM underlined red and flashing (GONG, LIMIT in a red box).
Certified for TM engine upgrade 2B1A. 
Modified FLI: 
P1 / T1 Transient torque layout change (red dot from 12.5 to 14).
V2000B (Part Number: ...04) 
Generator current limitation change: Gen. Amps underlined yellow 
when reaching 180 A (before 200 A). 
Certified for TM engine upgrade 2B1A_1 (TU45 installed). 
V2001A (Part Number: ...05) 
Integration of PW 206B2 engine. 
Mast moment over limit recording. 
CPDS configuration change possible via ARINC 485 bus included.
V2001B (Part Number: ...06) 
Mast moment exceedance can be deleted. 
Certification of the TRAINING MODE (single engine) for EC135 P1 
(PW 206B engines) and EC135 T1 (TM 2B1 engines).
Caution FUEL is integrated. 
V2002 (Part Number: ...07) 
Certification for Training Mode (dual engine) EC135 T2 (TM 2B2 
engines); integration of the modified fuel system.
V2003 (Part Number: ...08) 
Certification of Training Mode (dual engine) EC135 P2 (PW 206B2); 
integration of icing rate indication, inflight engine power check is now 
possible. 
V2005 (Part Number: ...09) 
This CPDS software is needed for the new EC135 T2+ / P2+ version.
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EC135 Classic 
B1 
Training Manual
01 – 137Iss. August 2018For instruction only
01 – General Information
1.9.41 CPDS Software Versions Overview
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.41 CPDS Software Versions Overview
EC135 Classic 
B1 
Training Manual
01 – 138Iss. August 2018For instruction only
V2010 (Port Number: ...10) 
Change of ice detection domain limits. 
Engine cycle counting increase from 4 to 5 digits. 
Change of minimum TOT domain limit from -60 °C to -110 °C for TM 
engines. 
Improved calculation (correct rounding) of mast–moment exceedance 
accumulated time in the maintenance mode. 
Indication of SW error 4001, 4002 and 4003 in maintenance mode. 
V2012 (Port Number: ...11) 
This CPDS software is needed for the new EC 135 P3 / T3 version. 
♦ NOTE For the certification status of the software version 
and the respective features refer to Flight Manual.
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01 – General Information
1.9.41 CPDS Software Versions Overview
EC135 Classic 
B1 
Training Manual
01 – 139Iss. August 2018For instruction only
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01 – General Information
1.9 Instrument Panel with CPDS
1.9.42 Hardware Changes according to H/C Serial Numbers in Production
EC135 Classic 
B1 
Training Manual
01 – 140Iss. August 2018For instruction only
1.9.42 Hardware Changes according to H/C Serial 
Numbers in Production
Up to S/N 120 
CPDS over temperature indication separate light (temperature sensor 
adjusted to 63 °C). 
Voltage adjustment unit installed under the cover of the instrument 
panel. 
S/N 121 and up 
CPDS over temperature indication integrated in the CAD caution list 
(temperature sensor adjusted between 51 °C and 55 °C). 
Voltage adjustment unit installed in the sensor units under the cabin 
floor. 
S/N 169 and up 
Only CPDS cockpit is available. 
S/N 218 and up
Maintenance connector installed in front of the center console (possible 
retrofit back to S/N 169). 
S/N 250 and up 
Modified fuel system (increased volume, modified vent lines and 
indication system). 
S/N 318 and up
CPDS software 2003. 
S/N 337 and up 
New interior fairing. 
S/N 445 and up 
The LH ventilation lines within the fuel cells are no more installed. 
S/N 505 and up 
MTOM 2910 kg, new twist grips, RH Air Data Computer is standard, a 
different type of gearbox oil is used in the main gearbox. 
S/N 830 and up 
New doubler and rivets at AFT ring frame X9227 of tail boom. 
S/N 870 and up 
New FWD ring frame X5730 at tail boom without life limit. 
S/N 1055 and up 
Upgrade to MTOM 2950 kg, incl. upgraded lead lag dampers.
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01 – General Information
1.9.42 Hardware Changes according to H/C Serial Numbers in Production
EC135 Classic 
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Training Manual
01 – 141Iss. August 2018For instruction only
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01 – General Information
1.10 Warning Unit
1.10.1 General
EC135 Classic 
B1 
Training Manual
01 – 142Iss. August 2018For instruction only
1.10 Warning Unit
1.10.1 General
The warning unit centrally monitors several systems and provides 
visual and audio indications of malfunctions.
Any failure of the CDS / CPDS has no effect on the warning unit.
Power Supply 
The warning unit is supplied by the ESSENTIAL BUSBAR 1 and 2 via 
the overhead panel installed circuit breakers: 
 – WARN SYS I 
 – WARN SYS II
Warning Indications 
The warning unit accomodates eight warning indications. They appear 
red when illuminated and black when inactive. Each warning indication 
simultaneously initiates a gong. 
The significance of the warning indications is outlined in the respective 
system chapters. The following are displayed: 
 – LOW FUEL 1 
 – LOW FUEL 2 
 – AP. A. TRIM (Autopilot) 
 – ROTOR RPM 
 – BAT TEMP 
 – BAT DISCH (Battery discharged) 
 – XMSN OIL P 
 – CARGO SMOKE
To test the function of the indicator lights and also the audio warnings, 
a test switch TEST CDS/WARN UNIT is installed in the overhead 
panel.
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01 – General Information
1.10 Warning Unit
1.10.1 General
EC135 Classic 
B1 
Training Manual
01 – 143Iss. August 2018For instruction only
Warning Unit
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01 – General Information
1.10 Warning Unit
1.10.2 AP. A. TRIMEC135 Classic 
B1 
Training Manual
01 – 144Iss. August 2018For instruction only
1.10.2 AP. A. TRIM
The warning AP. A. TRIM indicates a failure of the autopilot system. It 
is illuminated for 10 seconds. The signal is triggered by the autopilot 
computer. 
1.10.3 Rotor RPM
The ROTOR RPM warning monitors a total of three limit values. It 
reacts in various ways depending on which limit value is out of range.
 – rotor RPM < 95 % (< 97 % T2(+) / P2(+), T3 / P3) 
 – A steady red indication of ROTOR RPM and a pulsed tone 
is generated. (The pulsed tone can be switched off with 
AUDIO RES.) 
 – rotor RPM ≥ 106 % (T3 / P3 > gleich 107.5%) 
 – The red indication ROTOR RPM flashes and a gong can 
be heard. (The gong can be switched off with AUDIO 
RES.) 
 – rotor RPM ≥ 112 % 
 – The red indication ROTOR RPM flashes and a continuous 
tone is generated. (The tone cannot be switched off) 
1.10.4 BAT TEMP
The red indication BAT TEMP comes on when there is a battery 
overtemperature detected (above 70 °C). 
1.10.5 BAT DISCH 
The red indication BAT DISCH comes on, when the battery is 
discharged with more than 10 A. 
♦ NOTE BAT DISCH may also appear if the voltage of the EPU 
is below the voltage of the battery and the battery is 
discharged via the ESSENTIAL BUSSES. 
1.10.6 XMSN OIL P 
The red indication XMSN OIL P comes on when both oil pressure 
values in the main gearbox are below 0.5 bar. 
1.10.7 CARGO SMOKE 
The red indication CARGO SMOKE appears, when there is a signal 
from the smoke detector in the cargo compartment (optional).
1.10.8 LOW FUEL Warning 
A LOW FUEL warning is triggered by one of the sensors in the 
respective chamber of the supply tank.
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EC135 Classic 
B1 
Training Manual
01 – 145Iss. August 2018For instruction only
Warning Unit - Adjustment
01 – General Information
1.10.8 LOW FUEL Warning 
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01 – General Information
1.10 Warning Unit
1.10.9 FIRE Warning with EMER OFF SW Switch
EC135 Classic 
B1 
Training Manual
01 – 146Iss. August 2018For instruction only
1.10.9 FIRE Warning with EMER OFF SW Switch
The warning unit consists of the fire warning circuit and FIRE indication. 
The FIRE indication is inside the EMER OFF SW 1 and EMER OFF 
SW 2.
The fire warning circuit indicates individual firewarnings for engine 1 
and 2 and activates the fire extinguisher system if necessary. 
1.10.10 Fire Extinguisher System (optional) 
Fire extinguisher System activates the fire extinguisher bottles if 
the preconditions are fullfilled. Pressing the respective EMER OFF 
SW cuts the fuel supply to the engine and the ACTIVE indication 
illuminates.
1.10.11 N1 RPM Monitoring 
The N1 RPM is monitored for both engines separately. If the speed 
drops below 50 % signals are sent to the CPDS / CDS and the ENG 
FAIL caution is triggered.
1.10.12 Audio Warnings
There are four kinds of audio warnings. They have different priority 
and some of them can be suppressed by the switch CDS AUDIO / 
RES (located at the cyclic stick). But they reappear with each new 
warning. 
The following audio warnings exist in order of priority:
 – Continuous tone 
 – The continuous tone has a frequency of approx. 2400 Hz 
and cannot be suppressed. This tone is only activated by 
the signal ROTOR RPM ≥ 112 %. 
 – Pulsed tone 
 – The pulsed tone has a frequency of approx. 600 Hz and is 
generated with a 5 Hz rhythm. It can be suppressed. The 
pulsed tone is activated when ROTOR RPM is: < 95 % P1, 
T1; < 97 % P2, T2, P2+, T2+, T3 / P3. 
 – Gong 
 – The gong is generated every three seconds and can 
be suppressed. The gong is activated as soon as any 
warning (except fire warning) light illuminates or the LIMIT 
indication appears on the FLI. In the case of ROTOR RPM 
only if the value of 106 % (107.5 % P3 / T3) is exceeded. 
 – Fire bell 
 – Can be suppressed and is activated by fire warning.
♦ NOTE When there is a rotor RPM warning simultaneously 
with a fire warning, the warning unit produces the 
acoustic warning signal for rotor RPM ≥ 112 % and 
< 95 % P1, T1; < 97 % P2, T2, P2+, T2+, P3 / T3 only.
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B1 
Training Manual
01 – 147Iss. August 2018For instruction only
01 – General Information
1.10.12 Audio Warnings
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01 – General Information
1.11 Switch Unit
1.10.9 FIRE Warning with EMER OFF SW Switch
EC135 Classic 
B1 
Training Manual
01 – 148Iss. August 2018For instruction only
1.11 Switch Unit
General 
The switch unit has eight switches. They are provided for:
 – engine control (upper row) 
 – DC power control (lower row).
Engine Control Switches
For starting the engines two switches for each engine are provided: 
 – FADEC Switch (positions OFF–ON) 
to power the respective electronic engine governing 
 – ENGINE Main Switch (positions OFF–IDLE–FLIGHT)
to select engine start, engine IDLE and engine FLIGHT.
To prevent inadvertent operation of the Engine Main Switch, the switch 
has to be pulled out of a detent, and placed in the desired position. As 
a secondary safety device, two manual switch guards are installed to 
prevent unintended placement in the IDLE or OFF position.
DC Power Control Switches 
In the lower row of the switch unit the DC power control switches are 
installed. These are: 
 – two switches (GEN I, GEN II) for generator control with the 
positions NORM–OFF–RESET 
 – one switch BAT MSTR to control the power supply from the 
battery and from an external power source with the positions 
ON–OFF–RESET. 
♦ NOTE The switch BAT MSTR must be in Position “ON”, 
even when the helicopter is supplied by an EPU.
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01 – General Information
1.11 Switch Unit
1.10.12 Audio Warnings
EC135 Classic 
B1 
Training Manual
01 – 149Iss. August 2018For instruction only
Switch Unit
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01 – General Information
1.12 Overhead Console
1.12.1 General
EC135 Classic 
B1 
Training Manual
01 – 150Iss. August 2018For instruction only
1.12 Overhead Console
1.12.1 General
The overhead console which is part of the electrical power system is 
installed in the center of the cockpit roof. Busbars and circuit breakers 
supplying the electrical consumers are installed in the overhead 
console. Several systems are activated and / or controlled by switches 
in the overhead console. 
Components 
The overhead console consists of component brackets and the front 
panel. The front panel consists of three parts with a background 
lighting and the labelling of the installed circuit breakers, switches and 
rheostats. 
 – bus system 1 
 – bus system 2 
 – switch unit of the overhead panel. 
Bus Bars 
The following bus bars distribute the electrical current to the individual 
consumers: 
 – ESSENTIAL busbar 1 (PP10E) 
 – ESSENTIAL busbar 2 (PP20 E) 
 – SHEDDING busbar 1 (PP10S) 
 – SHEDDING busbar 2 (PP20S).
In addition, max. two bus bars can be installed for AC voltage (required 
for P&R SAS, weather radar, mechanical gyros...):
 – AC busbar 1 
 – AC busbar 2. 
Consumers with low energy demand and vital consumers for 
emergency conditions are connected to the two ESSENTIAL busbars. 
Further DC power consumers are connected to the SHEDDING bus 
bars (not supplied when only the battery is available or in case of 
double generator failure).
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EC135 Classic 
B1 
Training Manual
01 – 151Iss. August 2018For instruction only
Overhead Console (Example)
01 – General Information
1.12 Overhead Console
1.12.1 General
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01 – General Information
1.12 Overhead Console
1.12.2 Switch SHED BUS
EC135 Classic 
B1 
Training Manual
01 – 152Iss. August 2018For instruction only
1.12.2 Switch SHED BUS
The Switch SHED BUS has two positions: NORM and EMER. The 
NORM position is protected by a safety guard, which has to be opened 
before switching to the EMER position. 
 – NORM 
 – Both SHEDDING busbars are powered when the electrical 
systems are supplied by a minimum of one generator or 
by an EPU. 
 – EMER 
 – This position is used in order to supply both SHEDDING 
busbars from the battery in case of double generator 
failure. 
Switch BUS TIE I / II 
The switches BUS TIE I and BUS TIE II have three positions: NORM, 
OFF and RESET. The switches are protected by a safety guard, which 
forces the switch into the NORM position when closed. The following 
functions are provided: 
 – NORM 
 – When switching on the BAT MSTR, both bus tie contactors 
as well as the battery contactor close in order to connect 
the primary busbars and the battery busbar to each other. 
 – OFF 
 – The associated bus tie contactor opens/remains open in 
order to separate the two primary busbars. 
 – RESET 
 – In order to reactivate protective functions after a bus tie 
contactor had opened automatically by a system fault, the 
switch must be set to RESET before the contactor can be 
closed again by selecting the NORM position. 
Switch AC BUS SEL (if two inverters are installed) 
The switch AC BUS SELECT has three positions: NORM, INV 1 and 
INV 2. 
In position NORM each inverter supplies its own bus bar. In case of 
inverter failure, the remaining inverter can be switched on in order to 
supply both bus bars.
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EC135 Classic 
B1 
Training Manual
01 – 153Iss. August 2018For instruction only
Overhead Console - Switches and Controls (Example P2+)
01 – General Information
1.12.2 Switch SHED BUS
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01 – General Information
1.13 Pitot–Static System (FCDS)
1.12.2 Switch SHED BUS
EC135 Classic 
B1 
Training Manual
01 – 154Iss. August 2018For instruction only
1.13 Pitot–Static System (FCDS)
General 
The pitot-static system picks up the dynamic and static pressure of 
the ambient air of the helicopter via drain port remove from the lines. 
Electrical heating elements prevent the pitot tubes and static pressure 
ports from ice accumulation. 
Components
The pitot–static system of a cockpit consists of:
 – 2 pitot tubes
 – 4 static ports
 – static selector valve (only pilot's side)
 – 2 air data computer
 – 2 hose lines
 – 2 standby instruments
Locations 
The pitot tubes are located on the forward RH / LH side of the fuselage. 
The static ports are located two on each side of the fuselage below the 
equipment deck. The static selector valve is located on the right–hand 
side of the center part of the instrument panel. 
The components are connected with hose lines.
Function 
The static ports supply static pressure to the standby altimeter, to the 
standby airspeed indicator and to the Air Data Computer. Ram-air 
pressure from the pitot tubes are supplied only to the standby airspeed 
indicator and to the Air Data Computer. 
With the static selector valve it is possible to choose between ambient 
pressure and cabin pressure for the static pressure supply of the RH 
system, e.g. in case of blocked external static ports.
Pitot / Static Heating 
With the switch PITOT HTR in the overhead panel, the electrical 
heating for the pitot tubes and the static ports can be switched on.
There are two different versions for the indication in the cockpit: 
 – Version 1: A yellow caution appears in the respective field of 
the CPDS if the heating is switched off. 
 – Version 2: A yellow caution appears in the respective field 
of the CPDS if the heating is switched off. A green advisory 
appears if the heating is switched on (SW 2003).
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EC135 Classic 
B1 
Training Manual
01 – 155Iss. August 2018For instruction only
Pitot and Static Pressure System with FCDS
01 – General Information
1.13 Pitot–Static System (FCDS)
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01 – General Information
1.14 Handling of the EC135
1.14.1 Lifting
EC135 Classic 
B1 
Training Manual
01 – 156Iss. August 2018For instruction only
1.14 Handling of the EC135
1.14.1 Lifting
General
The helicopter can be lifted with main rotor blades installed or removed. 
For lifting a hoisting device is necessary. 
Procedure 
 – The hub cap must be removed. 
 – Carefully insert hoisting device into the hub cap support on 
the rotor mast and attach with bolt. 
 – Secure the bolt with the safety pin. 
 – Carefully lift helicopter while observing balance. 
 – Avoid jerky movements under all circumstances.
For the whole procedure refer to the applicable maintenance 
documentation.
♦ NOTE On early helicopter serial numbers the borehole in 
the support might be rotated to 45 ° and the tool can 
only be installed after the rotor blades have been 
removed.
♦ NOTE Older hoisting device models might be limited to 
2000 kg.
♦ NOTE When hoisting, the helicopter may tilt backwards.
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EC135 Classic 
B1 
Training Manual
01 – 157Iss. August 2018For instruction only
Hoisting Device
01 – General Information
1.14 Handling of the EC135
1.14.1 Lifting
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01 – General Information
1.14 Handling of the EC135
1.14.2 Jacking
EC135 Classic 
B1 
Training Manual
01 – 158Iss. August 2018For instruction only
1.14.2 Jacking
General
The helicopter can be jacked with four jacking brackets and four jacks. 
Special Tools 
The following special tools are necessary: 
 – four jacking brackets 
 – four jacks. 
Procedure 
 – The helicopter must be placed on an even and solid surface. 
In any case, the helicopter has to be grounded. 
 – The four jacking brackets must be attached to the fuselage 
landing gear fittings. 
 – The four jacks must be placed below the jacking brackets 
and the helicopter must be lifted evenly. Then the jacks must 
be locked.
For the whole procedure refer to the applicable mainentance 
documentation.
♦ NOTE The jacks must be actuated evenly. Otherwise the 
helicopter may tilt and be damaged!
♦ NOTE When jacking, the helicopter may tilt backwards.
1.14.3 Shoring
General
The helicopter can be shored at the tail boom. 
Tools 
 – Tail boom support 
Procedure
 – Place the helicopter on an appropriate surface and on a 
ground with a ground cable. 
 – Release the height adjustment lock of the tail boom support 
and retract the strut as required. 
 – Position the tail boom support behind the horizontal stabilizer 
and extend the strut until it touches the underside of the tail 
boom. Lock the strut using the height adjustment.
For the whole procedure refer to the applicable mainentance 
documentation.
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EC135 Classic 
B1 
Training Manual
01 – 159Iss. August 2018For instruction only
Jacking and Shoring
01 – General Information
1.14.3 Shoring
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01 – General Information
1.14 Handling of the EC135
1.14.4 Weighing
EC135 Classic 
B1 
Training Manual
01 – 160Iss. August 2018For instruction only
1.14.4 Weighing
General
Before the helicopter can be weight it must be leveled. 
Tools 
The following tools are necessary for weighing: 
 – two jacking brackets
 – one weighing bracket
 – three jacks 
 – weighing devices
 – spirit level / clinometer. 
Procedure
 – The helicopter must be placed on a even and solid surface in 
a closed draft–free hangar. 
 – Establish empty weight condition of helicopter in accordance 
with Flight Manual (FLM).
 – Determine individual weights of weighing bracket and of 2 
jacking brackets. 
 – Attach 2 jacking brackets to the aft landing gear fittings. 
Attach weighing bracket in the center of the front cross tube. 
Position one jack each with installed force measuring device 
below the jacking brackets and below the weighing bracket. 
 – Jack the helicopter. 
 – Apply spirit level or clinometer on cabin floor and level 
helicopter in horizontal position.
 – Read measuring values on the force measuring devices and 
record the weighing result in the weighing report. Calculate 
net values and moments.
 – Read measuring values on the force measuring devices and 
record the weighing result in the weighing report. Calculate 
net values and moments.
For the whole procedure refer to the applicable mainentance 
documentation.
♦ NOTE More exact measuring results are obtained by 
means of several weighing procedures.
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EC135 Classic 
B1 
Training Manual
01 – 161Iss. August 2018For instruction only
Jacking Brackets for Weighing
01 – General Information
1.14.4 Weighing
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01 – General Information
1.14 Handling of the EC135
1.14.5 Towing and Pushing
EC135 Classic 
B1 
Training Manual
01 – 162Iss. August 2018For instruction only
1.14.5 Towing and Pushing
General
The EC135 can be moved on ground by towing or pushing with 
manpower. 
Tools 
 – two transportation wheels 
 – towing bar. 
Procedure 
 – Install the two transportation wheels to the skid tube and the 
cross tube and lift the helicopter. 
 – Push the towing bar on LH and RH side on the skid tubes and 
lock it by use of the fixing bolt.
For the whole procedure refer to the applicable maintenance 
documentation.
Pushing
For pushing the helicopter, there are following pushing points in the 
fuselage area: 
 – Fenestron® housing and integrated control handles. 
 – LH and RH side shell below the engine deck 
 – LH and RH cabin structure 
 – landing gear cross tube. 
For pushing, the towing bar is not necessary.
♦ NOTE As a mechanical gyro is installed, the helicopter 
must not be moved within 15 minutes after switching 
off the battery or external power supply.
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B1 
Training Manual
01 – 163Iss. August 2018For instruction only
Transportation Wheel and Towing Bar
01 – General Information
1.14.5 Towing and Pushing
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01 – General Information
1.14 Handling of the EC135
1.14.6 Parking and Mooring
EC135 Classic 
B1 
Training Manual
01 – 164Iss. August 2018For instruction only
1.14.6 Parking and Mooring
General
To protect the helicopter from environmental influence, it has to be 
covered and the main rotor has to be tied down depending on weather 
conditions. 
Short-Time Covers 
All short-time covers are stowed in a storage sack, which should be 
carried on the helicopter during flights. 
The following short–time covers are available:
 – front windows
 – pitot tube
 – NACA inlets
 – NACA inlet roof
 – NACA inlet cowling
 – transmission inlet
 – engine outlet
 – Fenstron®
Procedure
 – All the electrical equipment has to be switched off. 
 – The helicopter must be grounded at the ground connection 
with the ground cable. 
 – Then all doors, windows and access doors must be closed.
♦ WARNING The engine outlets may be hot!
♦ NOTE Attach the short-time covers with the notice 
REMOVE BEFORE FLIGHT so that the notice flag is 
clearly visible outside.
 – The main rotor has to be turned in direction of rotation until 
one of the blades is aligned with the tail boom. 
 – The lashbag must be fitted over the end of the blade and 
secured to the tail boom by wrapping the attached belt and 
sack one full turn around the tail boom.
♦ NOTE Turn the main rotor only in direction of rotation.
For the whole procedure refer to applicable maintenance 
documentation.
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EC135 Classic 
B1 
Training Manual
01 – 165Iss. August 2018For instruction only
Covers (Example P3 / T3)
01 – General Information
1.14.6 Parking and Mooring
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166
01 – 
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1
EC135 Classic 
B1 
Training Manual
02 – 1Iss. August 2018For instruction only
02 – Lifting System
Chapter 02
Lifting System
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2
EC135 Classic 
B1 
Training Manual
02 – 2Iss. August 2018For instruction only
Table of contents
2.1 General Description of the Lifting System .................... 4
2.2 Main Rotor Drive .............................................................. 6
2.2.1 Driveshafts ......................................................................... 6
2.3 Main Transmission .......................................................... 8
2.3.1 General .............................................................................. 8
2.3.2 LH and RH Drives ............................................................ 10
2.3.3 Tail Rotor Output Drive .................................................... 12
2.3.4 Main Transmission .......................................................... 14
2.3.5 Lubrication System .......................................................... 18
2.3.6 XMSN Oil Temperature Indication ................................... 20
2.3.7 XMSN Oil Pressure Indication ......................................... 20
2.3.8 XMSN High Oil Temperature Caution .............................. 20
2.3.9 XMSN Oil Chip Caution ................................................... 20
2.3.10 XMSN Low Oil Pressure Caution / Warning .................... 22
2.3.11 Oil Distribution System .................................................... 24
2.3.12 Main Transmission Oil Service ........................................ 26
2.3.13 Accessory Gearbox ......................................................... 28
2.4 Oil Cooling System ........................................................ 30
2.5 Main Rotor Hub Shaft .................................................... 32
2.5.1 Main Rotor Hub Shaft - General ...................................... 32
2.5.2 Mast Moment Indication System ...................................... 34
2.5.3 Mast MomentIndication CDS .......................................... 36
2.5.4 Mast Moment Indication CPDS ........................................ 36
2.6 Rotor Brake System ...................................................... 38
2.6.1 Rotor Brake Indication System ........................................ 40
2.7 Main Transmission Mounts ........................................... 42
2.7.1 General ............................................................................ 42
2.7.2 ARIS Anti Resonance Isolation System ........................... 46
2.7.3 General System Description ............................................ 48
2.7.4 Clearance ........................................................................ 50
2.8 Oscillation Damper ........................................................ 52
2.9 Main Rotor System ........................................................ 54
2.9.1 General ............................................................................ 54
2.9.2 Main Rotor Blade ............................................................. 56
2.9.3 Blade Root ....................................................................... 58
2.9.4 Blade Fitting Area ............................................................ 60
2.9.5 Airfoil Section ................................................................... 62
2.9.6 Erosion Protection ........................................................... 64
2.10 Main Rotor Blade P3 / T3 Version ................................. 66
2.10.1 Rotor Blade Adjustments ................................................. 70
02 – Lifting System
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02 – Lifting System EC135 Classic 
B1 
Training Manual
02 – 3Iss. August 2018For instruction only
This training document comprises the following ATA chapters:
General Description of the Lifting System ATA 63
Main Rotor Drive ATA 63
Main Transmission ATA 63
Oil Cooling System ATA 63
Main Rotor Hub Shaft ATA 63
Rotor Brake System ATA 63
Main Transmission Mounts ATA 63
Oscillation Damper ATA 18
Main Rotor System ATA 62
Main Rotor Blade P3 / T3 Version ATA 62
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4
EC135 Classic 
B1 
Training Manual
02 – 4Iss. August 2018For instruction only
02 – Lifting System
2.1 General Description of the Lifting System
2.1 General Description of the Lifting System
General
The lifting System of the EC135 is located in the transmission 
compartment on top of the transmission deck, within the center-of-
gravity area. It's main components are:
 – Main rotor drive
 – rotor brake system
 – main rotor system
 – monitoring system
Main Rotor Drive
The main rotor drive system transmits power from both engines to the 
main– and tail rotor as well as to two cooling fans and two hydraulic 
pumps.
It mainly consists of:
 – 2 driveshafts
 – main transmission
 – main transmission mounts.
Rotor Brake System
The rotor brake system permits stopping of the main– and tail rotor, 
after the engines have been shut down. 
It mainly consists of:
 – cockpit mounted brake lever
 – bowden cable
 – brake cylinder
 – brake caliper
 – brake disk
Main Rotor System
The main rotor system generates the lift and thrust of the helicopter. 
In conjunction with the tail rotor system, it provides directional control 
of the helicopter in flight.
Monitoring System
For the important parameters (e.g. rotor RPM, oil pressure and oil 
temperature) several sensors are installed. The signals are transmitted 
to the cockpit in order to trigger cautions and warnings and supply the 
indicating instruments.
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EC135 Classic 
B1 
Training Manual
02 – 5Iss. August 2018For instruction only
Lifting System - General Arrangement
02 – Lifting System
2.1 General Description of the Lifting System
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02 – Lifting System
2.2 Main Rotor Drive
2.2.1 Driveshafts
EC135 Classic 
B1 
Training Manual
02 – 6Iss. August 2018For instruction only
2.2 Main Rotor Drive
General
The main rotor drive transmits power from both engines to the main 
rotor, tail rotor and to the auxiliary units. Additionally it is a structural 
component of the helicopter and also transmits all static and dynamic 
loads between the main rotor system and the fuselage.
Components of Main Rotor Drive
The main rotor drive consists of:
 – 2 driveshafts
 – main transmission
 – main transmission mounts
 – main rotor drive monitoring system.
2.2.1 Driveshafts
General
Two driveshafts connect the engines to the freewheel units of the 
main transmission. They transfer the power of the engines to the main 
transmission. In addition, they correct any misalignment between the 
engine outputs and the main transmission inputs. For this purpose two 
flexible diaphragms are attached to each end. 
A compensation in length is done by the engine output flange. 
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EC135 Classic 
B1 
Training Manual
02 – 7Iss. August 2018For instruction only
Engine Drive Shaft
02 – Lifting System
2.2 Main Rotor Drive
2.2.1 Driveshafts
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02 – Lifting System
2.3 Main Transmission
2.3.1 General
EC135 Classic 
B1 
Training Manual
02 – 8Iss. August 2018For instruction only
2.3 Main Transmission
2.3.1 General
The main transmission transfers the power from both engines 
to the main rotor system, tail rotor and the accessory drives. All 
mounting points, attachment fittings and oil lines are integral with the 
transmission casing. Two freewheel units incorporated in the input 
drives allow power to be transmitted only from the engines to the main 
transmission.
2.3.1.1 Components
The main transmission is of modular design. It mainly consists of:
 – LH and RH input drives
 – tail rotor drive
 – main gearbox
 – lubrication and cooling system
 – LH and RH accessory drives
Tab. 02-1: Leading Particulars Main Transmission
Mass approx. 143.5 kg
Gear reduction Main rotor 14.923
Tail rotor 1.183
Speed Drive 5898
Main rotor 385
Tail rotor output 4986
Oil quantity approx. 10.0 l
Oil types
AirGO 3001 for EC135 T2+ / P2+ and P3 / T3
alternatively: 0–156; MIL–L–23699 C for all 
other EC 135
Material Aluminium alloy
♦ NOTE Airbus Helicopters recommends AirGo 3001 for all 
EC135.
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EC135 Classic 
B1 
Training Manual
02 – 9Iss. August 2018For instruction only
Main Transmission - Modules
02 – Lifting System
2.3 Main Transmission
2.3.1 General
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02 – Lifting System
2.3 Main Transmission
2.3.2 LH and RH Drives
EC135 Classic 
B1 
Training Manual
02 – 10Iss. August 2018For instruction only
2.3.2 LH and RH Drives
Assembly
The drive consists of:
 – freewheel housing
 – freewheel unit
 – seal housing with seal
 – ball bearing and roller bearing
 – drive pinion.
Function
The driveshaft connecting the engine to the main transmission is 
attached to the triangular flange of the freewheel shaft. The bevel gear 
of the drive pinion meshes with the bevel gear of the intermediate 
shaft. The correct gear mesh (gear backlash and gear tooth pattern) 
is ensured by a shim of the appropriate thickness between the ball 
bearing and transmission casing. The shaft seal inthe cover seals off 
the rotating freewheel shaft at its outboard end.
Freewheel Unit
The engines drive the input drive shafts in clockwise direction. In 
this direction, the freewheel clutches are interlocking the driving and 
driven parts. 
The functions of the freewheel clutches are as follows:
 – Starting the engines: Only one engine drives initially and the 
freewheel clutch to the other drive is overrun. It will lock if 
both engines are running at the same RPM.
 – One engine becomes inoperative: It’s freeweel clutch is 
overrun and prevents the engine from being driven by the 
main transmission.
 – Both engines become inoperative: Both freewheel clutches 
are overrun and the main rotor can turn without any additional 
friction from the engines (autorotation).
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EC135 Classic 
B1 
Training Manual
02 – 11Iss. August 2018For instruction only
Freewheel Assembly 
02 – Lifting System
2.3.2 LH and RH Drives
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02 – Lifting System
2.3 Main Transmission
2.3.3 Tail Rotor Output Drive
EC135 Classic 
B1 
Training Manual
02 – 12Iss. August 2018For instruction only
2.3.3 Tail Rotor Output Drive
General
The tail rotor consists of:
 – connecting flange
 – spacer 
 – seal housing with shaft seal
 – output shaft
Assembly
The connecting flange provides the attachment point for the rotor brake 
disc adapter and the tail rotor driveshaft. The splined output shaft 
meshes with the splines of the connecting flange. The correct position 
of the connecting flange is adjusted by the gearbox manufacturer with 
the help of a spacer. The shaft seal in the seal housing seals off the 
rotating connecting flange at its outboard end.
♦ NOTE During the reinstallation of the connecting flange it 
must be ensured that the axial position relative to 
the output shaft is correct.
That means that the connecting flange must be in 
contact with the spacer. Otherwise an axial play of 
the output shaft is given. The actual position of the 
flange has an influence to the relative position of the 
rotor brake disc to the rotor brake calliper.
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EC135 Classic 
B1 
Training Manual
02 – 13Iss. August 2018For instruction only
Tail Rotor Output Drive
02 – Lifting System
2.3.3 Tail Rotor Output Drive
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02 – Lifting System
2.3 Main Transmission
2.3.4 Main Transmission 
EC135 Classic 
B1 
Training Manual
02 – 14Iss. August 2018For instruction only
2.3.4 Main Transmission 
General
The transmission concept was designed by ZF (Zahnradfabrik 
Friedrichshafen). The transmission is driven by two engines and 
drives the main rotor, the tail rotor and the accessories. 
The main transmission reduces the input RPM of the two engines 
to the required output RPM for the main rotor, the tail rotor and the 
accessories. The transmission is divided into the following stages:
 – input stage 
 – freewheel clutches
 – collector stage
 – accessory drives.
Input Stage
The LH and RH side engine input drive shafts are installed in the 
lower housing assembly. They are provided with freewheel clutches 
to prevent a reverse power flow from the main transmission to the 
engines. The two vertical intermediate gears change the power flow 
by 90° and pass it to the collector helical gear of the collector stage. 
Additionally, the intermediate shafts drive the oil pumps.
Collector Stage
The collector stage is the center part of the main transmission. The 
collector stage is driven by two intermediate gears. It transmits:
 – the combined engine power to the main rotor system and to 
the tail rotor system
 – the lifting forces into the transmission housing
 – dynamic and static forces from the lifting system.
Accessory Drives
Accessory drives are installed to drive the oil cooler fans and the 
hydraulic pumps. They are located at the LH and RH forward side of 
the main transmission and are driven by the intermediate gears.
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EC135 Classic 
B1 
Training Manual
02 – 15Iss. August 2018For instruction only
Main Gearbox - Geartrain and RPM (at 100%)
02 – Lifting System
2.3.4 Main Transmission 
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EC135 Classic 
B1 
Training Manual
02 – 16Iss. August 2018For instruction only
Main Gearbox, Lateral Cut, View against Flight Direction
02 – Lifting System
2.3.4 Main Transmission 
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EC135 Classic 
B1 
Training Manual
02 – 17Iss. August 2018For instruction only
Main Gearbox, Longitudinal Cut
02 – Lifting System
2.3.4 Main Transmission 
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02 – Lifting System
2.3 Main Transmission
2.3.5 Lubrication System
EC135 Classic 
B1 
Training Manual
02 – 18Iss. August 2018For instruction only
2.3.5 Lubrication System
General
The main transmission is provided with a wet sump oil system for 
lubrication and cooling. Because of redundancy, the lubrication system 
comprises two oil pumps located in the lower casing of the gearbox. 
The main components of the system are:
 – filler neck
 – oil filter
 – spray tubes
 – LH and RH oil pumps
 – oil sight glass
Oil is added to the system via the filler neck. The oil level is indicated 
by the oil sight glass. Oil is drained off through a valve which houses 
the chip detector.
Oil Pumps
The main transmission is equipped with a redundant lubrication 
system comprising two oil pumps located in the lower casing of the 
gearbox. These pumps are driven by the intermediate shafts through 
interconnected driveshafts. There is a predetermined breaking point 
integrated in these shafts. 
The oil pumps draw oil from the oil sump and convey it through a 
central oil passage. If either pump should fail, the remaining pump is 
able to convey enough oil to meet system demands. Failure of an oil 
pump is detected by a low–pressure switch and is visually indicated in 
the cockpit. In the central oil passage, an oil temperature transducer 
measures the oil temperature and an oil temperature switch monitors 
the max. permissible oil temperature. The associated indicators are 
located in the cockpit.
Oil Filter
An oil filter located in the central oil passage separates the contaminants 
from the oil. The housing of the oil filter is fitted with a bypass valve (∆p 
3.5 bar) and a mechanical filter contamination indicator (∆p 2.1 bar). 
This means that this pop–out is a preclogging indicator. If the filter 
becomes clogged, the oil will be rerouted through the bypass valve 
thereby maintaining the proper supply of oil to the system. 
An oil pressure transducer measures the oil pressure in the central oil 
passage. Visual indication of the pressure is provided in the cockpit. 
The oil is conveyed to both oil coolers and from there to the lubricating 
points through the integral oil passages in the casing. Installed at 
these lubricating points and accessible from the outside are spray 
tubes which provide for optimum lubrication of the components. 
The oil filter can be cleaned in an ultrasonic bath.
Oil Cooler
The oil coolers are mounted to the RH and LH side of the main 
transmission. They are split into two sections. The smaller sectionof each cooler, which is connected directly to the main transmission, 
serves for cooling the main transmission oil. 
For this, ambient air is drawn by the cooling fans and forced through 
the oil coolers via air ducts. From there, the air is directed overboard 
via outlet ducts (see also chapter “Power Plant”, Oil Cooling System).
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EC135 Classic 
B1 
Training Manual
02 – 19Iss. August 2018For instruction only
Main Transmission - Oil System
02 – Lifting System
2.3.5 Lubrication System
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02 – Lifting System
2.3 Main Transmission
2.3.6 XMSN Oil Temperature Indication
EC135 Classic 
B1 
Training Manual
02 – 20Iss. August 2018For instruction only
2.3.6 XMSN Oil Temperature Indication
General 
The oil temperature of the main gearbox is measured by a transducer 
mounted to the gearbox at the oil filter housing. The temperature is 
indicated in the cockpit on the analog oil temperature and pressure 
indication or on the VEMD in °C.
2.3.7 XMSN Oil Pressure Indication
General
The oil pressure is measured by a transducer mounted to the gearbox 
in the central oil passage. The pressure is indicated in the cockpit on 
the analog oil temperature and pressure indication or on the VEMD 
in bar.
Tab. 02-2: Oil Pressure 
Minimum 0.5 bar
Continuous operation 0.5 to 7.8 bar
2.3.8 XMSN High Oil Temperature Caution
General
The oil temperature caution caption is triggered by an oil temperature 
switch installed at the main transmission oil filter housing. The switch 
closes the circuit to the CDS / CPDS at a temperature of approx. 
115 °C. 
The indication at the MISC CAUTION display will be:
 – XMSN OIL T
2.3.9 XMSN Oil Chip Caution
General
For the detection of magnetic chips in the oil system, a chip detector is 
fitted in the common suction line of both oil pumps. It is installed by a 
bayonet connection in the XMSN oil drain plug (a check valve closes 
when the chip detector is removed). 
Accumulation of particles bridge a contact gap of the detector magnet 
and close the circuit to the CDS / CPDS. 
The indication at the MISC CAUTION display will be:
 – XMSN CHIP
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EC135 Classic 
B1 
Training Manual
02 – 21Iss. August 2018For instruction only
Main Transmission - Monitoring
02 – Lifting System
2.3.9 XMSN Oil Chip Caution
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02 – Lifting System
2.3 Main Transmission
2.3.10 XMSN Low Oil Pressure Caution / Warning
EC135 Classic 
B1 
Training Manual
02 – 22Iss. August 2018For instruction only
2.3.10 XMSN Low Oil Pressure Caution / Warning
General
To warn the pilot in case of low oil pressure in each of the XMSN 
lubrication systems, two pressure switches are installed downstream 
of the oil pumps. The switches are installed at the lower front side of 
the main transmission.
2.3.10.1 Low Oil Pressure Caution
Each oil pressure switch closes when the pressure at the associated 
pump outlet is below 0.5 bar. 
The associated indication are as follows:
 – XMSN OIL P Caution SYS I or II on CDS / CPDS 
2.3.10.2 Low Oil Pressure Warning
In case of low oil pressure in both XMSN lubrication systems (both 
pump outlet pressure switches sense a pressure below 0.5 bar) a low 
pressure warning will be sent additionally to the CDS / CPDS caution 
captions. 
The associated indications are as follows:
 – XMSN OIL P Cautions SYS I and II on CDS / CPDS
 – XMSN OIL P Warning on the warning unit
 – gong in the headset with 3 seconds intervals.
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EC135 Classic 
B1 
Training Manual
02 – 23Iss. August 2018For instruction only
Main Transmission - Oil Pressure Switches
02 – Lifting System
2.3.10 XMSN Low Oil Pressure Caution / Warning
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02 – Lifting System
2.3 Main Transmission
2.3.11 Oil Distribution System
EC135 Classic 
B1 
Training Manual
02 – 24Iss. August 2018For instruction only
2.3.11 Oil Distribution System
General
The distribution system delivers oil to all bearings and gears in the 
main gearbox as well as to the accessory drives and the freewheel 
clutches. The system mainly consists of bores in the gearbox housing 
and spray nozzles, screwed into the gearbox housing. After lubricating 
the gears and bearings, the oil flows into the oil sump in the lower 
housing by gravity.
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EC135 Classic 
B1 
Training Manual
02 – 25Iss. August 2018For instruction only
Main Transmission - Components of Lubrication System
02 – Lifting System
2.3.11 Oil Distribution System
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02 – Lifting System
2.3 Main Transmission
2.3.12 Main Transmission Oil Service
EC135 Classic 
B1 
Training Manual
02 – 26Iss. August 2018For instruction only
2.3.12 Main Transmission Oil Service
The following oil type is approved for the main transmission: 
 – MIL-L-23699 
 – AirGO 3001 for EC135 T2, T2+, P2, P2+ 
The oil quantity is approx. 10.0 liters.
2.3.12.1 Oil Level Sight Glass
The main transmission oil level can be checked by a sight glass, 
located at the RH rear side of the main transmission. 
The “MAX” and “MIN” marks indicate the upper and the lower oil level 
limits.
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EC135 Classic 
B1 
Training Manual
02 – 27Iss. August 2018For instruction only
Main Transmission - Oil Service
02 – Lifting System
2.3.12 Main Transmission Oil Service
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02 – Lifting System
2.3 Main Transmission
2.3.13 Accessory Gearbox
EC135 Classic 
B1 
Training Manual
02 – 28Iss. August 2018For instruction only
2.3.13 Accessory Gearbox
General
A fan drive gearbox consists of:
 – gearbox housing
 – idler gear witch ball bearing
 – driveshaft with bevel gear and bearings
 – output pinion gear with ball bearings.
Configuration and Function
The intermediate shaft of the main gearbox drives the idler gear and 
the driveshaft of the accessory gearbox. The driveshaft is splined to 
the hydraulic pump. The flange for the hydraulic pump encases the 
driveshaft seal. The bevel gear of the driveshaft drives the output 
pinion gear of the fan. The fan bearings are lubricated with main 
gearbox oil.
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EC135 Classic 
B1 
Training Manual
02 – 29Iss. August 2018For instruction only
Accessory Gearbox
02 – Lifting System
2.3.13 Accessory Gearbox
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02 – Lifting System
2.4 Oil Cooling System
2.3.13 Accessory Gearbox
EC135 Classic 
B1 
Training Manual
02 – 30Iss. August 2018For instruction only
2.4 Oil Cooling System
General
Both engines as well as the main transmission of the helicopter 
are equipped with internal, independent oil circuits. These ensure 
permanent lubrication and cooling of highly stressed componentsunder all operating conditions. To keep the oil temperature within 
limits, a oil cooling system is installed in the helicopter.
Independant cooling circuits are availble for the:
 – LH engine
 – RH engine
 – main transmission.
Components
The oil cooling system consists of the following:
 – 2 cooling fans
 – 2 inlet airducts
 – 2 outlet airducts
 – 2 dual section oil coolers (engine / main transmission)
 – 2 thermal controlled bypass valves in the engine circuits
 – severeal hoses and connectors
Cooling Fans
The cooling fans aremounted at the front side of the main transmission 
RH and LH. They are driven by the main transmission geartrain (12666 
RPM at 100 %).
Oil Cooler
The oil coolers are mounted at the RH and LH side of the main 
transmission. They are split into two sections. The smaller section 
of each cooler, which is connected to the main transmission by feed 
tubes directly, serves for cooling the main transmission oil. 
The larger section of each cooler is connected to the associated 
engine by oil hoses. This section serves for cooling the engine oil.
Cooling Air Flow
Ambient air which enters the air intakes is drawn by the cooling fans 
and forced through the oil coolers via the inlet air ducts. From there 
the air is directed overboard by the outlet ducts.
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EC135 Classic 
B1 
Training Manual
02 – 31Iss. August 2018For instruction only
Oil Cooling System - General Arrangement
02 – Lifting System
2.4 Oil Cooling System
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02 – Lifting System
2.5 Main Rotor Hub Shaft
2.5.1 Main Rotor Hub Shaft - General
EC135 Classic 
B1 
Training Manual
02 – 32Iss. August 2018For instruction only
2.5 Main Rotor Hub Shaft
2.5.1 Main Rotor Hub Shaft - General
The main rotor hub shaft transmits the driving moment to the main 
rotor blades which are connected to the hub. In doing so, it also 
performs the function of a rotor head. 
The main rotor hub shaft assembly consists of the following 
components:
 – rotor hub shaft with integral flanges
 – hub cap support
 – rotor hub cap.
Configuration
The main rotor hub shaft, which is hollow and is formed with two hub 
flanges at its upper end, is a one–piece forged part made of steel 
alloy. In between the two flanges the rotor blades are fixed. 
The two fixation points for the scissors assembly are forged to the 
shaft. On the lower end of the shaft are the seating surfaces for the 
mast bearings and the mast spline which meshes with the main 
transmission. 
The upper hub flange is marked with the numbers 1 through 4 at the 
blade attachment areas, with the numbers counted in the clockwise 
direction. This identification is important for relating the blade 
attachment areas to their respective blades.
Bonding Jumper
Four bonding jumpers are screwed onto the hub cap support with 
one end and to bonding studs at the rotor blades. This allows static 
discharge of the rotorblades.
Hub Cap Support
The hub cap support, which is manufactured from aluminum alloy, 
is attached by screws to the upper hub flange of the main rotor hub 
shaft, and seals off the open end of the hub shaft. 
The helicopter can be lifted by a hoisting device attached to the hub 
cap support.
Rotor Hub Cap
For aerodynamic reasons, a rotor hub cap is installed. It is a composite 
construction which can be delivered in two different types:
 – standard rotor hub cap
 – quick–removable rotor hub cap for blade folding system 
(optional).
The hub caps are attached to the support by screws in the case of the 
standard hub cap and by bayonet connections and safety screws in 
the case of the quick–removable hub cap.
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EC135 Classic 
B1 
Training Manual
02 – 33Iss. August 2018For instruction only
Main Rotor Hub Shaft
02 – Lifting System
2.5 Main Rotor Hub Shaft
2.5.1 Main Rotor Hub Shaft - General
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02 – Lifting System
2.5 Main Rotor Hub Shaft
2.5.2 Mast Moment Indication System
EC135 Classic 
B1 
Training Manual
02 – 34Iss. August 2018For instruction only
2.5.2 Mast Moment Indication System
General
The mast moment indication system is used to measure and indicate 
any bending moments, which occur on the rotor mast. 
The system mainly consists of:
 – strain gauge bridge 
 – sensor amplifier unit
 – induction transmitter (stator and rotor)
 – signal processing unit
 – indication at the CDS / CPDS.
Function
The signal processing unit (SPU) produces a certain frequency which 
is transmitted to the signal amplifier unit (SAU). 
The signal is transferred via stator, attached to the lower gearbox cover 
in the oil sump, and rotor of the induction transmitter. The SAU sends 
a signal (carrier frequency) to the strain gauge bridges, bonded into 
the rotor mast. Due to shaft bending, the resistance of the strain gauge 
bridge changes thus modulating the amplitude of the carrier frequency. 
The SAU amplifies the SGB signal and converts it to a frequency 
signal (25 kHz ±10 kHz). 25 kHz corresponds to 0% mast moment 
(MM) resp. 0V SGB signal. This frequency signal is modulated on a 
13.56MHz carrier frequency. This 13.65 MHz frequency is generated 
by the SPU and also supplies the SAU with power. The modulated 
signal is transmitted back from the SAU via the induction transmitter 
to the SPU. The signal processing unit generates a voltage signal 
proportional to the bending moment. This voltage signal is sent to the 
CDS / CPDS for mast moment indication.
♦ NOTE The signal processing unit can be installed under 
the transmission deck or above the avionics deck in 
the rear of the helicopter.
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EC135 Classic 
B1 
Training Manual
02 – 35Iss. August 2018For instruction only
Mast Moment Indication System
02 – Lifting System
2.5.2 Mast Moment Indication System
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02 – Lifting System
2.5 Main Rotor Hub Shaft
2.5.3 Mast Moment Indication CDS
EC135 Classic 
B1 
Training Manual
02 – 36Iss. August 2018For instruction only
2.5.3 Mast Moment Indication CDS
The CDS mounted mast moment indicator consists of a green, a 
yellow and a red bar and an additional red “limit light”.
Tab. 02-3: Mast Moment Indication CDS
Normal range up to 50 % green
Caution range 50 % to 78 % yellow
Maximum 78 % to 100 % red
When the mast moment exceeds 63.15 % and is below 77.80 %, the 
red limit light flashes at approx. 3 flashes / second. When the mast 
moment is reduced to less than 63.15 %, the limit light extinguishes.
When the mast moment exceeds 77.80 %, the limit light is turned on 
continuously. It remains on until a CDS cold start occurs. The actual 
cumulated counter value is stored in 200 ms steps in the CDS memory 
and can be displayed in the advisory display by turning the rotary knob 
to the “M” position. (Example: 0017 = 17 x 200 ms = 3.4 s)
2.5.4 Mast Moment Indication CPDS
The mast moment indication at the VEMD consists of a white marking 
with different ranges. The following ranges are allocated to single 
colors:
Tab. 02-4: Mast Moment Indication CPDS
Normal range up to 50 % no color
Caution range 50 % to 66 % yellow
Maximum > 66 % red
♦ NOTE 50 % equal 9500 Nm bending moment.
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B1 
Training Manual
02 – 37Iss. August2018For instruction only
Mast Moment Indication System
02 – Lifting System
2.5.4 Mast Moment Indication CPDS
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02 – Lifting System
2.6 Rotor Brake System
2.5.3 Mast Moment Indication CDS
EC135 Classic 
B1 
Training Manual
02 – 38Iss. August 2018For instruction only
2.6 Rotor Brake System
General
The hydro-mechanical rotor brake system enables the main and tail 
rotors to be brought to a standstill, and locks them against further 
rotation for a limited period of time. With the brake lever applied 
and locked, the hydraulic pressure in the rotor brake system will be 
maintained for some time before slowly dissipating. An electrical 
switch lights up a caption in the cockpit indicating system that the rotor 
brake has been engaged.
♦ NOTE The rotor brake may only be operated under the 
following conditions: the engines have been shut 
down or the rotor speed is down to 50 % of its 
nominal speed
System Components
The rotor brake system mainly consists of:
 – brake lever (located in the cockpit)
 – bowdenflex cable
 – damper (force limiter spring)
 – brake cylinder with fluid reservoir
 – brake caliper
 – brake disk
 – micro switch for CDS/CPDS caution ROTOR BRK.
Function
The rotor brake is actuated by a brake lever. Before it can be operated, 
the brake lever must be released from its detent by actuating a 
locking pawl which allows the brake lever to be pulled downward until 
it engages. The maximum force is limited by the damper spring. To 
release the brake lever, the locking pawl on the brake lever must be 
pressed.
♦ NOTE The fluid reservoir must be filled with brake fluid 
DOT–4 only.
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EC135 Classic 
B1 
Training Manual
02 – 39Iss. August 2018For instruction only
Rotor Brake System
02 – Lifting System
2.6 Rotor Brake System
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02 – Lifting System
2.6 Rotor Brake System
2.6.1 Rotor Brake Indication System
EC135 Classic 
B1 
Training Manual
02 – 40Iss. August 2018For instruction only
2.6.1 Rotor Brake Indication System
General
A micro switch that is installed on the brake caliper mounting slideway 
will indicate an engaged rotor brake an the rotor brake indicating 
system. The slide itself is installed on the rotor brake support in a way 
that it can move laterally against a spring by approximately 1 mm. Two 
springs (one on each slide bolt) press the slide to the right (seen in 
flight direction). The force to move the slide can be adjusted by shims 
(also on left hand side). 
If the rotor brake is engaged and the brake disk starts turning, the 
brake caliper will move together with the slide against the spring and 
depress the microswitch. 
The indication on the CDS/CPDS MISC caution display will be:
 – ROTOR BRK
♦ NOTE With an engaged rotor brake and a stillstanding 
rotor, the caution ROTOR BRK is not triggered. 
With an engaged brake the caution will come on the 
moment the rotor starts turning.
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B1 
Training Manual
02 – 41Iss. August 2018For instruction only
Rotor Brake Indication System
02 – Lifting System
2.6.1 Rotor Brake Indication System
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02 – Lifting System
2.7 Main Transmission Mounts
2.7.1 General
EC135 Classic 
B1 
Training Manual
02 – 42Iss. August 2018For instruction only
2.7 Main Transmission Mounts
2.7.1 General
The main transmission is attached to the airframe by four ARIS (Anti 
Resonance Isolation System) dampers, one side load strut (Y-Strut) 
and two torque struts. 
The components of the main transmission mounting serve to transmit 
the main rotor forces and moments into the helicopter airframe.
Gearbox Struts
One (titanium) side load strut (Y–strut) carries all forces in lateral (Y) 
direction. The side load strut is attached to the airframe via a combined 
torque / Y–load bracket on the LH side of the transmission deck. 
The strut is attached to the main transmission accesscover by means 
of two screws. 
Two titanium torque struts carry the main rotor reaction torque and all 
forces created by the main rotor system in longitudinal (X) direction.
The torque struts are attached to the airframe and to the main 
transmission by bolts. Spherical bearings are integrated in the torque 
struts. 
In case of a torque strut failure the emergency stop keeps the gear 
box in position and prevent a total failure of the ARIS mounts.
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EC135 Classic 
B1 
Training Manual
02 – 43Iss. August 2018For instruction only
Main Gearbox - Attachment
02 – Lifting System
2.7 Main Transmission Mounts
2.7.1 General
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B1 
Training Manual
02 – 44Iss. August 2018For instruction only
INTENTIONALLy LEFT BLANK
02 – Lifting System
2.7 Main Transmission Mounts
2.7.1 General
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B1 
Training Manual
02 – 45Iss. August 2018For instruction only
Gearbox Struts
02 – Lifting System
2.7 Main Transmission Mounts
2.7.1 General
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02 – Lifting System
2.7 Main Transmission Mounts
2.7.2 ARIS Anti Resonance Isolation System
EC135 Classic 
B1 
Training Manual
02 – 46Iss. August 2018For instruction only
2.7.2 ARIS Anti Resonance Isolation System
Principle
In order to isolate a vibration between the rotor system and the aircraft 
fuselage a spring/mass damper is used. 
The spring rate and the mass weight have to be defined in such a way 
that the main rotor frequency induces the anti resonance oscillation in 
the spring/mass system. Thus the H/C rotor system and the damping 
mass vibrate with the same frequency, with phase shift of 180°. 
Therefore, the forces generated by the rotor system in downward 
direction are compensated by the forces created by the dampingmass 
in upward direction and vice versa.
This system is only effective in the vertical axis (z–direction) and 
towards the adjusted frequency.
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EC135 Classic 
B1 
Training Manual
02 – 47Iss. August 2018For instruction only
Principle of Passive Anti–Resonance Vibration Isolation
02 – Lifting System
2.7.2 ARIS Anti Resonance Isolation System
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02 – Lifting System
2.7 Main Transmission Mounts
2.7.3 General System Description
EC135 Classic 
B1 
Training Manual
02 – 48Iss. August 2018For instruction only
2.7.3 General System Description
The system consists of 4 uniaxial hydro-mechanical vibration isolaters. 
They carry all weight and lifting forces transmitted by the main 
transmission. They are attached to the airframe with 4 bolts each and 
to the main transmission by a special spherical bearing and one bolt 
each. For “fail safe” purposes an emergency stop is mounted above 
each damper. 
The purpose of the system is to reduce the loads and vibrations 
generatedby the main rotor to the helicopter fuselage.
Function
The vibrations generated by the main rotor cause periodic movements 
of the main transmission relative to the fuselage which in turn causes 
axial movement of the primary bellows. 
In response to the travel of the primary bellows, the secondary bellows 
produce a bigger stroke as determined by the ratio of their respective 
cross-section areas. The resultant inertia forces (force generator) 
cause the pressure of the glycol solution in the vibration isolator to 
fluctuate. The spring and pressure forces at the isolator attachment 
point on the fuselage overlap each other. Therefore, vibrations are 
reduced at the anti–resonance frequency. 
The primary bellows are provided with an adapter at the bottom end 
for connecting them to the fuselage, while at the top end they are 
formed with a forked lug for connecting them to the main transmission. 
The forked lug is fitted with bushings. Above the bellows section, the 
primary bellows are formed with an integral ring above which there is 
an annular groove which accomodates a split emergency stop ring. 
At the upper end of the secondary bellows there is a mass jacket. A 
pendulum rod acting as a guide for the mass is attached to this jacket. 
A pre–loaded compression spring together with the secondary 
bellows produce an operating pressure within the self-contained unit 
of approx. 6 to 7 bar, thereby ensuring the functional integrity of the 
vibration isolator for all operating conditions. 
The emergency stop which is formed in the shape of a cylindrical pot 
fits over the corrugated portion of the primary bellows and is attached 
to the transmission deck of the fuselage with screws. 
If the primary bellows of the vibration isolator should fail, the 
transmission will be supported either by the emergency stop or the 
detachable emergency stop rings.
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EC135 Classic 
B1 
Training Manual
02 – 49Iss. August 2018For instruction only
ARIS - Vibration Isolators
02 – Lifting System
2.7.3 General System Description
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02 – Lifting System
2.7 Main Transmission Mounts
2.7.4 Clearance
EC135 Classic 
B1 
Training Manual
02 – 50Iss. August 2018For instruction only
2.7.4 Clearance
The clearance between stop ring and emergency stop must have a 
certain value. For measuring this clearence, a feeler gauge is used at 
four places 90° apart and the mean value has to be calculated. 
The clearance is adjusted with shims to the nominal value 0.7 to 
1.0 mm during installation.
♦ NOTE The clearance will change with the temperature and 
therefore can’t be used for failure detection.
Adjustment
A main rotor speed of 100 % nR means that the main rotor rotates at 
6.6 rounds per second. This results in a 4/rev vibration frequency of 
26.3 Hz. The natural vibration frequency of the ARIS is adjusted to 
this figure.
Failure Detection
At +20 °C the pendulum rod will protrude. The protrusion varies with 
the ambient temperature, but generally it can be stated, that as long 
as the pendulum rod protrudes the ARIS is still serviceable.
In case of pressure drop (e.g. crack in one of the bellows) the internal 
spring and the inner bellows expand and the pendulum rod will 
disappear.
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EC135 Classic 
B1 
Training Manual
02 – 51Iss. August 2018For instruction only
ARIS - Measurement of Clearance
02 – Lifting System
2.7.4 Clearance
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02 – Lifting System
2.8 Oscillation Damper
2.7.4 Clearance
EC135 Classic 
B1 
Training Manual
02 – 52Iss. August 2018For instruction only
2.8 Oscillation Damper
General
The aircraft is equipped with a mass / spring damper to reduce lateral 
vibrations (y direction). It is mounted to the fuselage and compensates 
for lateral vibrations created by the main rotor system.
Location and Assembly
The y–damper is mounted to the stringer below the LH floor panel.
The damper assembly consists of two weights bolted to the springs. 
The location of the weights on the springs is adjustable. On each 
weight it is possible to attach up to 6 tuning sheets. The springs, with 
the weights attached, are mounted to a common support.
Function
The damper is energized by lateral oscillations of the fuselage. The 
natural frequency of the damper can be adjusted by adjusting the 
weights of the mass or moving the weights on the springs. If the 
damper frequency is tuned to the same frequency as the fuselage 
oscillations, it will vibrate in exact opposition to the fuselage vibrations. 
Those induced vibrations of the damper will react in direct opposition 
to the fuselage vibrations and will cause a reduction in fuselage lateral 
vibrations. 
The y–damper is adjusted to give the lowest level of vibrations at 
101.5 % NR instead of 100 % NR. This is in order to achieve the best 
compromise of vibration levels when the rotor speed increases to 104 
% NR at high density altitudes. 
A main rotor speed of 101.5 % NRR means that the main rotor rotates at 
6.7 revolutions per second. This results in a 4/rev vibration frequency 
of 26.7 Hz. The natural vibration frequency of the y damper is adjusted 
to this figure.
♦ NOTE If the H/C flies permanently in higher altitudes, the 
efficiency of the damper can be adjusted by removing 
a certain amount of tuning sheets (according service 
engineering information).
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EC135 Classic 
B1 
Training Manual
02 – 53Iss. August 2018For instruction only
y–Damper
02 – Lifting System
2.8 Oscillation Damper
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02 – Lifting System
2.9 Main Rotor System
2.9.1 General
EC135 Classic 
B1 
Training Manual
02 – 54Iss. August 2018For instruction only
2.9 Main Rotor System
2.9.1 General
The main rotor system consists of a bearingless, hingeless 4–blade 
main rotor, main rotor shaft with integral hub, control elements, and 
the rotor-related indicators. By using modern composite materials, 
this rotor system provides the flapping, lead–lag and blade pitch 
change functions without the installation of complicated ball and 
elastomeric bearings. This type of construction is beneficial in terms 
of maintenance, cost and weight.
System Components
The components of the main Rotor systems are:
 – four main rotor blades
 – main rotor hub shaft
 – swash plate
 – four rotating control rods
 – scissors assembly (driving unit)
Main Rotor Blades
The four main rotor blades generate the lift and propulsion required for 
flight. Each blade is attached to the hub-shaft by two identical bolts.
Main Rotor Hub-Shaft
The main rotor hub–shaft transmits the driving torque from the main 
transmission to the main rotor blades. It also takes up rotor forces and 
moments and passes them to the main transmission.
Swash Plate
The swashplate is the connecting link between the rotating rotor and 
the stationary components of the control system. It is mounted on a 
sliding sleeve which slides on a main gearbox mounted support tube.
Rotating Control Rods
The four rotating control rods transmit the control inputs from the 
swashplate to the main rotor blades. For flight control adjustment 
(track and balance), the control rods are length–adjustable.
Driving Unit
Two scissors assemblies provide for synchronous rotation of the 
swashplate bearing ring with the rotor mast.
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EC135 Classic 
B1 
Training Manual
02 – 55Iss. August 2018For instruction only
Main Rotor System
02 – Lifting System
2.9 Main Rotor System
2.9.1 General
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02 – Lifting System
2.9 Main Rotor System
2.9.2 Main Rotor Blade
EC135 Classic 
B1 
Training Manual
02 – 56Iss. August 2018For instruction only
2.9.2 Main Rotor Blade
General
The main rotor blade is manufactured from fiber composite materials. 
A blade root having low bending stiffness (Flex Beam) performs 
the functions of the flap and lead-lag hinges. Because of the weak 
torsional stiffness of the FlexBeam, the angle of attack of the blade 
can be changed. 
A pitch control cuff is integrated in the blade skin to provide a rigid 
connection with the airfoil section of the blade. The pitch angle of 
the main rotor blade is changed through a pitch horn on the pitch 
control cuff. During this feathering motion, the pitch control cuff is kept 
centered about the blade root by a bearing support and a spherical 
bearing.
Two elastomeric lead–lag dampers provide sufficient in-plane damping 
of the main rotor blade to prevent ground and air resonance.
The surface of the main rotor blade is provided with a protective coat 
of PUR lacquer to protect the composite materials from solar radiation 
and environmental and weather influences.
Color Marking
Each of the four main rotor blades is identified with a different color. 
The upper hub flange of the main rotor hub–shaft is coded with the 
numbers 1 thru 4 on the blade attachment areas. In order to avoid 
readjusting the control settings and the blade track when removing 
or installing the same main rotor blades, these main rotor blades are 
reinstalled so that their respective colors are paired correctly with 
number codes on the hub flange. 
Blade number 1 (yellow colour code) is the reference blade. On the 
blade 1 (yellow) only the settings determined by the manufacturer (test 
bench) for the pitch link, so called “pre track value” can be changed. 
This reference of the blade 1 ensures the basic rotor adjustment (min. 
and max. pitch angle). The settings of the blades 2, 3 and 4 are also 
set to the manufacturers basic settings (“pre track value”). Additionally 
the blades 2,3 and 4 are individually adjusted (pitch link length and 
trim tab position) according the results of the track and balance run. All 
blades can be replaced individually due to the manufacturers' basic 
settings. The numbers and colour codes for the blades 2, 3 and 4 are 
mainly used as a reference for the track and balance equipment.
♦ NOTE If the basic adjustment is changed, the relationship 
between the rotor thrust and the collective pitch 
lever position will be out of tolerance. Depending 
on the amount of deviation, the autorotation RPM 
and the general helicopter performance will be 
influenced.
♦ NOTE The main rotor blades can be replaced individually 
due to the adjustments at the manufacturers' test 
stand.
Color to Number Code Relationship
 – Yellow = number 1
 – Green = number 2
 – Blue = number 3
 – Red = number 4
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B1 
Training Manual
02 – 57Iss. August 2018For instruction only
Main Rotor Blade
02 – Lifting System
2.9.2 Main Rotor Blade
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02 – Lifting System
2.9 Main Rotor System
2.9.3 Blade Root
EC135 Classic 
B1 
Training Manual
02 – 58Iss. August 2018For instruction only
2.9.3 Blade Root
The blade root has the following functional areas:
Blade fitting area (1)
Serves to attach the main rotor blade to the rotor hub of the main rotor 
shaft and is fitted for this purpose with two Teflon–coated bushings.
Soft flapping section (2)
This area enables the main rotor blade to flap up and down.
Soft torsion section (3)
Enables the main rotor blade to twist about its feathering axis to 
change the blade pitch angle.
Soft lead-lag section (4)
Enables in-plane motion of the main rotor blade.
Pitch Control Cuff
The pitch control cuff is provided with a transition area where it is 
integrated with the aerodynamic portion of the blade, and with a 
damper connection at its open end. The pitch control cuff, which 
permits neither torsional nor lead–lag movements, surrounds the 
blade root and is rigidly connected to the adjacent airfoil section. 
Torsional stiffness is required so that the control inputs can be 
transmitted through the pitch control cuff to the airfoil section of the 
blade. 
The in–plane rigidity of the pitch control cuff is obtained through the 
unidirectional orientation of its carbon fibers in the trailing and leading 
edge of the control cuff. Lead–lag rigidity is necessary to enable lead-
lag movements of the main rotor blade to be transmitted directly to the 
lead-lag dampers without significant losses. 
To prevent denting of the pitch control cuff – especially on the less 
curved upper and lower surfaces – it incorporates a sandwich structure 
and a hard foam filler core. 
Two drain holes are provided on the underside of the pitch contol cuff 
at the outboard end adjacent to the blade airfoil section. These serve 
to vent the pitch control cuff and to allow water which has condensed 
in or penetrated the pitch control cuff to drain off. 
The integration (transition area) of the pitch control cuff to the blade 
body provides a force transmitting connection which transmits the 
control inputs to the aerodynamic portion of the blade. A part of the 
forces andmoments generated by the main rotor blade are transmitted 
through this connection to the pitch control cuff. 
A positive twist of +16° built into the blade in the region where the 
pitch control cuff joins the airfoil section provides the airfoil section 
with a corresponding preset pitch angle and brings the flexbeam into 
an unloaded (untwisted) mid position.
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EC135 Classic 
B1 
Training Manual
02 – 59Iss. August 2018For instruction only
Main Rotor Blade - Control Cuff
02 – Lifting System
2.9.3 Blade Root
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02 – Lifting System
2.9 Main Rotor System
2.9.4 Blade Fitting Area
EC135 Classic 
B1 
Training Manual
02 – 60Iss. August 2018For instruction only
2.9.4 Blade Fitting Area
A composite damper connection is integrated in the fiber structure 
of the pitch control cuff. In the areas where it connects to the lead-
lag dampers, it is constructed with extreme stiffness to withstand 
compression loads. This is necessary because the lead-lad dampers 
have to be axially preloaded during installation. 
The damper connection is tilted 15° relative to the blade fitting plane 
in the direction of the pitch horn. 
The pitch control cuff is supported at the blade fitting end by the 
damper installation consisting of the elastomeric lead-lag dampers 
and the bearing support which provides pivotal and tilting movements. 
When control inputs are made, the pitch control cuff rotates about this 
pivot point. Simultaneously, the flexbeam twists to feather the main 
rotor blade about its longitudinal axis and provide the required pitch 
angle. 
The pitch control cuff provides the following functions:
 – transmits control inputs to the aerodynamic portion of the 
blade to change the blade pitch angle
 – transmits in-plane movements of the main rotor blade to the 
lead-lag dampers
 – provides the blade root with an aerodynamicfairing.
♦ NOTE The blade bolt bushings are tilted 2.5° against the 
rotor blade longitudinal axis in order to cone up 
the blade. Thus the forces in the blade fitting are 
reduced when the rotor is turning.
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EC135 Classic 
B1 
Training Manual
02 – 61Iss. August 2018For instruction only
Main Rotor Blade - Blade Fitting Area and Pitch Control
02 – Lifting System
2.9.4 Blade Fitting Area
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02 – Lifting System
2.9 Main Rotor System
2.9.5 Airfoil Section
EC135 Classic 
B1 
Training Manual
02 – 62Iss. August 2018For instruction only
2.9.5 Airfoil Section
The airfoil section generates the main rotor blade lifting force. It has 
a rectangular blade geometry with a parabolic swept-back tip and a 
negative 2° twist per meter. The blade airfoil consists of:
 – a homogenous section comprising the DM-H4 airfoil up to 
R = 4500 mm
 – a transition area between airfoil DM-H4 and airfoil DM-H3 
between R = 4500 and R = 4800 mm
 – the blade tip comprising the DM-H3 airfoil between R = 4800 
and R = 5100 mm.
Blade Core
The hard-foam blade core provides the supporting structure for the 
blade contour and stabilizes the blade skin.
Blade Spar
The blade spar consists of glassfiber rovings. They run from the blade 
tip to the blade root, around the bushings in the blade fitting area, and 
back to the tip. They absorb the tension and bending forces.
Lead Rod
The lead rod in the blade leading edge determines the required 
position of the blade center of gravity (CG)in chordwise direction.
Blade skin
The blade skin, which is made of GRP plies, surrounds the spar, lead 
rod and blade core. It ensures that the aerodynamic portion of the 
blade is provided with the necessary torsional stiffness. The skin plies 
on the upper and lower surfaces of the blade converge at the blade 
trailing edge where they are squeezed together to complete a torsion 
box.
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EC135 Classic 
B1 
Training Manual
02 – 63Iss. August 2018For instruction only
Main Rotor Blade - Airfoil Section
02 – Lifting System
2.9.5 Airfoil Section
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02 – Lifting System
2.9 Main Rotor System
2.9.6 Erosion Protection
EC135 Classic 
B1 
Training Manual
02 – 64Iss. August 2018For instruction only
2.9.6 Erosion Protection
An erosion protection is bonded on the entire length of the blade 
leading edge. Between the blade tip and approx. the middle of the 
homogenous airfoil section, the erosion protection is composed of 
nickel alloy or aluminum alloy on old-type blades. The surface of the 
aluminum alloy erosion protection is hardened. In the area adjacent to 
the erosion protection, where there is less risk of erosion, an erosion 
protective tape (one or two parts) made of polyurethane (PU) is 
integrated in the blade skin. A PU erosion protective film is bonded 
on the paint coat covering the butt joints between parts of the erosion 
protection and the forward edge of the pitch control cuff.
Balance Chamber
A balance chamber is incorporated in the main rotor blade near the 
blade tip. Preliminary settings made in the balance chamber by the 
manufacturer ensure that the blades can be replaced individually. 
These presettings must not be changed by the customer.
Static Discharger
A static discharger is riveted to the blade trailing edge in the blade tip 
area. It consists of an adapter, a threaded fitting and the discharger 
rod. The static discharger enables the discharge of static electricity 
from the helicopter. An electrical conducting strap is embedded in the 
blade skin to electrically connect the static discharger to the bonding 
jumper connecting point. The conducting strap runs along the erosion 
protection from the static discharger to the pitch control cuff. A flexible 
bonding jumper electrically connects the main rotor blade to the main 
rotor hub-shaft.
Blade Tip Mass and Tuning Mass
The blade tip mass increases the rotor inertia and stabilizes the rotor 
RPM (e. g. autorotation). The tuning mass changes the resonance 
frequency of the rotor blade in order to stay clear of other main 
frequencies in the rotor system.
Trim Tabs
Two metal trim tabs and one FRP tab are bonded and, in addition, 
riveted to the trailing edge near the blade tip. The trim tabs enable the 
track of the main rotor blades to be adjusted so that they all fly in the 
same tip path plane. Both metal trim tabs may be bent to make track 
adjustments.
Dynamic Balancing Washers
The balance washers for dynamic balancing are attached to the pitch 
control cuff under a cover.
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EC135 Classic 
B1 
Training Manual
02 – 65Iss. August 2018For instruction only
Main Rotor Blade
02 – Lifting System
2.9.6 Erosion Protection
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02 – Lifting System
2.10 Main Rotor Blade P3 / T3 Version
2.9.6 Erosion Protection
EC135 Classic 
B1 
Training Manual
02 – 66Iss. August 2018For instruction only
2.10 Main Rotor Blade P3 / T3 Version
General
Basically the main rotor blade of the P3 / T3 Version is identically to 
the P1 / T1 to PE / TE version from the blade root until blade station 
R4500.
Main Changes
The main changes are:
 – airfoil section lenght increased
 – airfoil section twist change at R4500
 – airfoil section between R4500 to R5200 includes
 – new foam cores and impact web
 – new blade tip mass
 – trim tabs moved outboard
 – fixed trim tab removed
Airfoil Section
The airfoil section generates the main rotor blade lifting force. To 
increase the efficency, the length of the airfoil section is increased by 
100 mm. Between blade root and blade station R4500, the new blade 
is identicall to the old blades. 
At blade station R4500, the blade twist and the length is increased 
with a parabolic sweep–back tip. 
The Ni–Co erosion protection is elongated to new blade length. 
There is no change in position, shape and size of the balancing 
chamber.
New Core and Impact Web
Shape and size of foam core 6 and 7 has change to adapt the new 
length and twist of the blade. To improve the skin impact stability at the 
blade tip, a double–C impact web is integrated between foam core 6 
and 7. The leading edge of foam core 7 is reinforced rovings.
Blade Tip Mass
The new blade tip mass length is increased to 170 mm with a straight 
shape and a weight of 1700 gr. Additonal retaining rovings are 
integrated to keep the blade tip mass in position.
Trim Tabs
To increase the effciency of the trim tabs, the installation position is 
moved 50 mm to the tip. The fixed trim tab is no longer installed.
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EC135 Classic 
B1 
Training Manual
02 – 67Iss. August 2018For instruction only
Main Rotor Blade P3 / T3
02 – Lifting System
2.10 Main Rotor Blade P3 / T3 Version
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02 – Lifting System
2.10 Main Rotor Blade P3 / T3 Version
2.9.6 Erosion Protection
EC135 Classic 
B1 
Training Manual
02 – 68Iss. August 2018For instruction only
Lead Lag Dampers and Bearing Support
The lead-lag dampers are attached to the damper connection of the 
pitch control cuff by screws installed through the bottom aluminumplates. The top steel plates of the dampers are connected by nuts 
to the ends of the bearing support, thereby connecting the lead-lag 
dampers to each other through the bearing support. Both lead-lag 
dampers are preloaded upon their connection to the bearing support. 
This prevents tension loading of the elastomer material during control 
inputs and blade flapping movements. Tension loads would greatly 
reduce the service life of the lead-lag dampers.
The lead-lag dampers are installed tilted in relation to the rotor plane 
due to the canted damper connection (see View V). This layout enables 
a kinematic coupling to be obtained between the lead-lag motion and 
the pitch angle of the main rotor blade. This coupling provides for a 
large part of blade lead-lag damping during flight. 
In the bearing support a spherical bearing is mounted which allows 
pivoting and tilting movements. The bearing support together with the 
lead-lag dampers support the open end of the pitch control cuff and 
center it around the blade root.
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02 – Lifting System
2.10 Main Rotor Blade P3 / T3 Version
EC135 Classic 
B1 
Training Manual
02 – 69Iss. August 2018For instruction only
Pitch Control Cuff and Blade Root
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02 – Lifting System
2.10 Main Rotor Blade P3 / T3 Version
2.10.1 Rotor Blade Adjustments
EC135 Classic 
B1 
Training Manual
02 – 70Iss. August 2018For instruction only
2.10.1 Rotor Blade Adjustments
Manufacturer Adjustments
All four blades of the EC135 main rotor can be replaced individually. 
On a rotor test stand the deviation of the dynamic behaviour of the 
master blade is detected and corrected. In order to stay within the 
manufacturer limits the following parameters have to be adjusted.
Longitudinal Moment (Static Spanwise Balancing)
The longitudinal moment can be adjusted by changing weights in the 
center of the balance chamber which is exactly in the center of gravity 
line the longitudinal axis. To determine the individual setting a special 
weighing equipment is necessary.
♦ NOTE Any change of the longitudinal moment (e. g. 
application of paint in different radius stations of 
the rotor blade) will influence the blade behaviour 
significantly and abnormal vibrations can occur.
Lateral Moment (Chordwise Balancing)
The lateral moment determines the lift and therefore the track level 
of the rotor blade under different pitch angles. With the adjustment 
of the lateral moment the characteristic of the master blade can be 
transferred to all produced blades. 
By shifting mass behind the longitudinal center of gravity line the 
increase of the lateral moment creates more lift with a higher track 
level and vice versa.When leaving the production line the balance 
chamber normally is equipped with 12 weights (6 in front of, 6 behind 
the center of gravity line). To harmonise production tolerances brass 
or several combinations of brass and tungsten weights can be used.
After the measurements on the rotor test stand weights can be shifted 
forward and backward in order to achieve the master blade track 
level. The plastic spacers between the metallic weights allow a lateral 
transfer of weight without influence on the longitudinal moment.
Pretrack Value
For the first rotor blade adjustment the rotating pitch links normally 
are set to a basic length. As a fine tuning towards the master blade 
the basic length can be altered according the measurements on the 
rotor test stand. The pretrack value is a dimension in +/- [mm] for the 
change of the basic pitch link length and is stamped on the respective 
control cuff and the rotor blade log card. Thus the necessary flight 
time for the track and balance adjustment can be reduced.
♦ NOTE Every time one or more rotor blades are replaced 
the pretrack value has to be adjusted at first, even 
for blade number 1 (yellow reference blade). For 
any further track adjustment the pitch link length of 
blade number 1 must not be changed.
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EC135 Classic 
B1 
Training Manual
02 – 71Iss. August 2018For instruction only
Balance Chamber
02 – Lifting System
2.10.1 Rotor Blade Adjustments
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72
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B1
Training Manual
02 – Lifting System
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1
EC135 Classic 
B1 
Training Manual
03 – 1Iss. August 2018For instruction only
03 – Fuselage
Chapter 03
Fuselage
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2
EC135 Classic 
B1 
Training Manual
03 – 2Iss. August 2018For instruction only
Table of contents
3.1 Reference Planes ............................................................. 4
3.2 Leveling ............................................................................ 6
3.3 Fuselage General Description ........................................ 8
3.4 Cabin Structure .............................................................. 10
3.5 Main Fuselage Structure ............................................... 12
3.5.1 Engine Deck .................................................................... 14
3.5.2 Cabin Floor ...................................................................... 16
3.6 Doors .............................................................................. 18
3.6.1 Emergency Door Jettison ................................................ 20
3.6.2 Sliding Doors ................................................................... 22
3.6.3 Rear Doors ...................................................................... 24
3.7 Service Covers ............................................................... 26
3.8 Windows ......................................................................... 28
3.9 Cowling ........................................................................... 30
3.10 Placards and Markings .................................................. 32
3.10.1 General ........................................................................... 32
This training document comprises the following ATA chapters:
Reference Planes ATA 06
Leveling ATA 08
Fuselage General Description ATA 53
Cabin Structure ATA 53
Main Fuselage Structure ATA 53
Doors ATA 52
Service Covers ATA 52
Windows ATA 56
Cowling ATA 71
Placards and Markings ATA 11
03 – Fuselage
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B1
Training Manual
03 – Fuselage
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4
EC135 Classic 
B1 
Training Manual
03 – 4Iss. August 2018For instruction only
03 – Fuselage
3.1 Reference Planes
3.1 Reference Planes
General
The frame coordinates of the EC135 are defined in accordance with 
LN 65619 (Luftfahrtnorm). All dimensions are given in the metric 
system (mm). The reference planes are used to determine locations 
on and within the helicopter.
Definitions
Locations on and within the helicopter can be determined in relation to 
fuselage stations, buttock lines (BL) and waterlines (WL), measured 
in millimeters (mm) from known reference points. Fuselage stations 
(FS), buttock lines, and waterlines are planes perpendicularto each 
other.
Reference plane is the plane at the longitudinal centerline of the 
helicopter perpendicular to the cabin floor.
Fuselage Stations
Fuselage stations (FS) are vertical planes perpendicular to, and 
measured along, the longitudinal axis of the helicopter. 
Station 0 is an imaginary vertical plane in front of the nose of the 
helicopter, from which all horizontal distances are measured for 
balance purposes (see also “reference datum”).
Buttock Lines (+ / - y Coordinates, Lateral)
Buttock lines (BL) are vertical planes perpendicular to, and measured 
to the left and right along the lateral axis of the helicopter. 
Buttock line 0 is the plane at the longitudinal centerline of the helicopter.
Waterline (+ Z Coordinates, Vertical)
Waterlines (WL) are horizontal planes perpendicular to, and measured 
along, the vertical axis of the helicopter. 
Waterline 0 is a plane 1505 mm below and parallel to the cabin floor.
Reference Datum (+ X Coordinates Longitudinal)
The reference datum (RD) is an imaginary vertical plane in front of 
the helicopter nose. The station is located 4000 mm in front of the 
leveling point (center of double frame #4) and 1099.32 mm in front of 
the helicopter standard nose cover.
♦ NOTE The standard helicopter is well clear to the reference 
planes in order to avoid negative coordinates (X; Z) 
after exterior optional equipment is mounted.
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EC135 Classic 
B1 
Training Manual
03 – 5Iss. August 2018For instruction only
Reference Planes
03 – Fuselage
3.1 Reference Planes
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03 – Fuselage
3.2 Leveling
EC135 Classic 
B1 
Training Manual
03 – 6Iss. August 2018For instruction only
3.2 Leveling
General
The helicopter is leveled and dimensions are checked in accordance 
with a specified procedure. This is to verify all design dimensions. The 
leveling data sheet (measuring report) must be kept in the historical 
record for future reference. This procedure must be repeated after 
major modifications or repairs after hard landings.
Procedure
The following activities must be performed:
 – Ground the helicopter.
 – Remove external equipment if installed.
 – Defuel the helicopter.
 – The helicopter must be placed on an even and solid surface 
in a closed draft-free hangar.
 – Level the helicopter.
 – Check the horizontal and vertical measuring points.
 – Check the angles.
 – Record all measuring results in the measuring record.
♦ NOTE A measuring point is marked by a rivet with a colored 
circle.
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EC135 Classic 
B1 
Training Manual
03 – 7Iss. August 2018For instruction only
Measuring Points
03 – Fuselage
3.2 Leveling
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03 – Fuselage
3.3 Fuselage General Description
EC135 Classic 
B1 
Training Manual
03 – 8Iss. August 2018For instruction only
3.3 Fuselage General Description
General
The fuselage serves as platform for the helicopter systems, crew, 
passengers and payload. The exterior shape of the fuselage is 
dictated by the major functions during operation and typical usage of 
light helicopters.
Components
The components of the fuselage are:
 – cabin structure (cabin frame and roof structure)
 – main fuselage structure (transmission deck, side shells, 
engine deck, rear attachment cone, eqipment deck, cabin 
floor, subfloor structure and bottom shell) 
 – rear structure (tail boom with horizontal stabilizer and 
Fenestron® structure)
 – doors and service covers
 – windows.
Modular Concept
The modular concept simplifies the assembly of the helicopter and 
permits the replacement of individual modules without disassembling 
the entire fuselage.
Materials
The following materials are used:
 – aluminium
 – titanium
 – composite materials (glass-, carbon-, KEVLAR®-fiber) 
 – acrylic glass.
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EC135 Classic 
B1 
Training Manual
03 – 9Iss. August 2018For instruction only
Fuselage
03 – Fuselage
3.3 Fuselage General Description
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03 – Fuselage
3.4 Cabin Structure
EC135 Classic 
B1 
Training Manual
03 – 10Iss. August 2018For instruction only
3.4 Cabin Structure
General
The cabin structure comprises the forward section above the cabin 
floor. It is designed to function as a frame. It consists of: 
 – cabin framework 
 – cabin roof 
 – center post. 
Cabin Framework
The cabin framework is a one-piece structural component. It is 
constructed as a hollow profile made of composite material, mainly 
carbon–fiber, but also glass–fiber and KEVLAR® is used. The 
framework provides the structural support for mounting the windshields, 
the nose windows, the pilot / copilot doors and the sliding doors to the 
passenger compartment. The upper fork end of the windshield center 
post houses the overhead panel. 
Threaded inserts in the area of the window frame profiles are provided 
for installation of the front and nose windows. 
Cabin Roof 
The cabin roof covers the cabin framework. It also functions as a 
fairing for the main rotor control rod system. 
The cabin roof is made of composite material (mainly carbon but also 
glass–fiber is used.) To get more stiffness, partly NOMEX® cores are 
integrated. For lightning protection a copper mesh is used as a final 
layer. 
The roof is riveted to the cabin framework. To allow access to the 
control rods and the upper bellcrank assembly, a handhole is provided 
in the upper right side of the cabin roof dome. 
♦ NOTE The cabin roof is a non load carrying structure. NO 
STEP!
Center Post 
The center post is installed between the cabin floor and the cabin 
roof. It only houses the vertical control rods for main rotor control. The 
center post is made of aluminum sheetmetal. It is displaced slightly to 
the RH side of the helicopter to allow the pilot having an unobstructed 
view to the rear left. 
♦ NOTE The center post is a non load carrying structure.
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EC135 Classic 
B1 
Training Manual
03 – 11Iss. August 2018For instruction only
Cabin Structure
03 – Fuselage
3.4 Cabin Structure
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03 – Fuselage
3.5 Main Fuselage Structure
EC135 Classic 
B1 
Training Manual
03 – 12Iss. August 2018For instruction only
3.5 Main Fuselage Structure
General
The main fuselage structure is the part of the fuselage that carries all 
the loads transmitted by the main transmission from the main rotor 
system and all the loads caused by the engines, landing gear and tail 
unit.
Components
The main fuselage structure consists of the following:
 – body structure
 – floor structure.
The body and floor structure are rigidly attached to each other.
Body Structure
The predominantly aluminum-alloy body structure is composed of 
individual assemblies which are:
 – side panels LH/RH
 – transmission deck 
 – engine deck
 – rear structure attachment cone 
 – equipment deck.
The body structural components are rigidly attached to each other.
Side Panels 
The side panels, which provide the framework on the sides of the 
body structure, consist of frames 4 thru 7 and stringers. The outer 
skin, which is aluminum alloy, is riveted to the frames and stringers.Integrated in the side panels are maintenance steps. The left–hand 
side panel also incorporates a housing for accomodating the fuel filler 
neck. 
The outer skin of each side panel is provided with cutouts for the aft 
window panes and the cooling vents. 
Attached to the outside of both side panels is a center door rail for 
guiding the respective sliding door. 
Transmission Deck 
The transmission deck, which takes up the load of the lifting system, 
consists of frames 4 thru 5 and longitudinal beams. It is attached by 
rivets to the side panels. On the transmission deck six mounts for 
main transmission installation are provided. The transmission deck 
skin is aluminum alloy.
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EC135 Classic 
B1 
Training Manual
03 – 13Iss. August 2018For instruction only
Side Panels and Transmission Deck
03 – Fuselage
3.5 Main Fuselage Structure
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03 – Fuselage
3.5 Main Fuselage Structure
3.5.1 Engine Deck
EC135 Classic 
B1 
Training Manual
03 – 14Iss. August 2018For instruction only
3.5.1 Engine Deck
The engine deck,which supports the engines, consists of frames 6 
and 7 and longitudinal beams. It is riveted to the transmission deck 
and to the side panels.The engine deck is equipped with mounts to 
which the engine is attached through its mounting struts. 
Integral with the upper surface of the engine deck is the rear structure 
attachment cone. 
As the engine deck is part of the firewall-system, the skin is made from 
titanium sheet metal. 
Rear Structure Attachment Cone 
The rear structure attachment cone is rigidly connected to the 
transmission deck. The rear structure is connected to the main 
fuselage structure through connecting frame 8 which is riveted to the 
rear structure attachment cone. The rear structure attachment cone is 
stiffened by frame 5a. 
Equipment Deck 
The equipment deck provides amounting base for items of equipment 
such as the engine fire extinguishing system components, battery, 
etc. It is an aluminum honeycomb structure which is supported by a 
carbon fiber ring frame and is riveted to the engine deck through shear 
brackets.
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EC135 Classic 
B1 
Training Manual
03 – 15Iss. August 2018For instruction only
Engine Deck, Attachment Cone, Equipment Deck
03 – Fuselage
3.5.1 Engine Deck
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03 – Fuselage
3.5 Main Fuselage Structure
3.5.2 Cabin Floor
EC135 Classic 
B1 
Training Manual
03 – 16Iss. August 2018For instruction only
3.5.2 Cabin Floor
The cabin floor supports the seats and parts of the interior furnishings 
of the helicopter. It is an aluminum honeycomb sandwich construction 
and comprises the following sections:
 – forward floor
 – aft floor
 – left and right cable channel cover.
In the forward floor are cutouts for the flight control elements and 
wiring harnesses. Fastened to the forward floor are the pilot seats, 
controls, consoles and the center post. 
Integrated into the removable aft floor are tracks running in a 
longitudinal direction. These enable the helicopter to be configured 
with passenger seats or items of special operational equipment. 
The removable side channel covers cover the area of the floor between 
the forward and aft floors and the cabin side panels.
Subfloor Structure
The subfloor structure, which is a aluminum–alloy construction, 
supports the cabin floor and the landing gear. It is made up of frames 
1 thru 6 and two longitudinal beams. The structure is riveted to the 
side panels through the frames and the lower shell. 
There is a transverse bridge between the longitudinal beams behind 
frame 1 and in front of frame 2. 
A forward and an aft landing gear fitting are riveted to each of the two 
longitudinal beams. 
The fuel tanks are located between frames 3 and 5 and behind 
frame 5, respectively.
Lower Shell
The lower shell is a one–piece composite structure reinforced with 
NOMEX® core. The skin is a mixture of prepreg fabrics which consists 
of carbon, glass and polyester. The structure encloses the subfloor 
structure and supports the fuel tanks. It is riveted to the subfloor 
structure. 
A maintenance hole is provided in the lower shell between frames 1 
and 2 and between 2 and 3, respectively. 
Running laterally below each frame 2 and 5 is a tunnel which is 
occupied by a landing gear crosstube. 
In the area behind frame 3 and in front of and behind frame 5, the lower 
shell is stiffened to provide a firm mounting base for the equipment 
plates. 
A lower door rail for guiding the sliding door is integrated in the upper 
edge of the lower shell between frames 2 and 4 on each side.
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EC135 Classic 
B1 
Training Manual
03 – 17Iss. August 2018For instruction only
Floorboard, Subfloor Structure, Lower Shell
03 – Fuselage
3.5.2 Cabin Floor
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03 – Fuselage
3.6 Doors
3.5.2 Cabin Floor
EC135 Classic 
B1 
Training Manual
03 – 18Iss. August 2018For instruction only
3.6 Doors
General
The helicopter fuselage is fitted with six entrance doors to provide 
access to the cockpit, passenger cabin and cargo compartment.
Cockpit Doors 
The cockpit doors (pilot doors) are hinged doors located left and right 
at the forward part of the cabin frame. In the standard version they can 
not be jettisoned. 
The cockpit doors are a carbon–glass–fiber composite construction 
with a seal fitted to their circumference. They are installed to the cabin 
framework via two hinges with integral bearings and two clevis fittings. 
The upper one is attached by rivets and the lower one by screws. 
The rear edges of the pilot doors are fitted with locking devices at 
the top and at the bottom. They are operated through the exterior 
or interior door handle and the interconnecting lever and connection 
rods. The claws of the locking devices engage with the mating fittings 
on the cabin framework. The pilot door can be locked with an integral 
door lock. A gas spring holds the unlatched pilot door wide open. 
In a second version the gas spring is removed and the door can be 
locked in the full open position in the vicinity of the pitot tubes. 
Cockpit Door Windows 
The pilot door windows are made of 3 mm thick acrylic glass. They 
are positioned on a layer of adhesive sealant in the door structure and 
secured to the latter by countersunk screws and dimpled washers.
The pilot door windows incorporate smaller sliding windows which can 
be moved on rails by means of a handgrip bonded to the pane. The 
sliding windows are held in the selected open position on the rails by 
friction. A mechanical detent locks them in the closed position so that 
they cannot be opened from the outside.
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EC135 Classic 
B1 
Training Manual
03 – 19Iss. August 2018For instruction only
Cockpit Door
03 – Fuselage
3.6 Doors
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03 – Fuselage
3.6 Doors
3.6.1 Emergency Door Jettison
EC135 Classic 
B1 
Training Manual
03 – 20Iss. August 2018For instruction only
3.6.1 Emergency Door Jettison
General
The pilot and copilot door is equipped with an emergency door jettison 
system. Aftera touch down or an emergeny landing on water the doors 
can be jettisoned by operating the lever.
Components
The main components of the system are:
 – lever 
 – upper and lower linkage 
 – door hinge bolt
Function
When the lever is operated, the upper and lower door hinge bolts are 
released via the linkage. Now the door can be pushed outside.
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EC135 Classic 
B1 
Training Manual
03 – 21Iss. August 2018For instruction only
Emergency Door Jettison
03 – Fuselage
3.6.1 Emergency Door Jettison
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03 – Fuselage
3.6 Doors
3.6.2 Sliding Doors
EC135 Classic 
B1 
Training Manual
03 – 22Iss. August 2018For instruction only
3.6.2 Sliding Doors
The sliding door is a carbon-glass-fiber composite construction. It is 
fitted with a door seal around its entire circumference except for the 
edge adjacent to the pilot door. The upper arm with a runner and the 
lower guide with a roller are attached to the forward corners of the 
sliding door. The sliding door is moved on its upper arm and lower 
guide along an upper rail in the cabin framework and a lower rail in 
the lower shell. The aft armwith an integral runner is fitted on the rear 
edge of the sliding door. By means of this arm, the sliding door also 
runs on a rail located in the side panel. 
The sliding door is opened and closed via the exterior door handle or 
interior door handle, and the associated locking mechanism. Latching 
of the sliding door is provided by an inner tube which matches with 
a fitting in the cabin framework above the sliding door, and by a lock 
which matches aft with a corresponding fitting in the side panel.
For flight with open sliding door the locking mechanism for the open 
position has to be installed and the speed limits have to be obeyed.
Sliding Door Windows 
The sliding door windows are made of 3 mm acrylic glass. They are 
fitted in the sliding doorswith a peripheral clamping sealwhich enables 
them to be removed quickly to provide an escape in the event of an 
emergency. 
Emergency Exit 
The clamping seal of the sliding door window is formed with four slits. 
Of these, the two lateral inner and outer slits are each fitted with a filler 
(Rubber cord with matching profile) which expands the circumference 
of the clamping seal so that the window is held firmly in the door 
frame. The filler in the inner or outer lateral slit can be pulled out of 
the clamping seal by means of an emergency handle on the inside 
and outside of the the sliding door. To prevent inadvertent pulling, the 
emergency handles are protected by pushbutton–fixed covers. After 
the filler has been removed, the window pane can be pressed out of 
the sliding door.
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EC135 Classic 
B1 
Training Manual
03 – 23Iss. August 2018For instruction only
Sliding Door
03 – Fuselage
3.6.2 Sliding Doors
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03 – Fuselage
3.6 Doors
3.6.3 Rear Doors
EC135 Classic 
B1 
Training Manual
03 – 24Iss. August 2018For instruction only
3.6.3 Rear Doors
The rear door structure is a carbon, glass polyester hybrid prepreg 
construction, reinforced with NOMEX® cores. The edges of the rear 
doors are fitted with a door seal. Two fittings are attached by screws 
to each rear door. With these fittings, the rear doors are connected to 
themain fuselage structure.A gas spring attached to the inside of each 
rear door (by the help of a fitting) holds the unlatched door open. Two 
locking mechanisms are installed on the edge of the right–hand door 
which, when the doors are closed, clasp the mating sleeves on the 
edge of the left–hand door. Both rear doors are latched together from 
the outside and then locked with a key.
Rear Door Windows
The rear door panes are made of 2 mm thick acrylic glass. They are 
bonded to the rear door structure and are secured by screws.
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EC135 Classic 
B1 
Training Manual
03 – 25Iss. August 2018For instruction only
Rear Doors
03 – Fuselage
3.6.3 Rear Doors
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03 – Fuselage
3.7 Service Covers
3.6.3 Rear Doors
EC135 Classic 
B1 
Training Manual
03 – 26Iss. August 2018For instruction only
3.7 Service Covers
General
Installed on the fuselage, there are a number of service covers which 
can be removed to get access to components inside the helicopter.
Handhole Cover 
The handhole cover, which is constructed of carbon fiber, has a seal 
bonded to its inside edges. It is attached by screws to the cabin roof 
cowling and provides access to the upper main rotor control linkage 
when removed. 
Nose Cover 
The nose cover, which is a sandwich construction made out of carbon 
and glassfiber prepreg with NOMEX® core, has a seal bonded 
to its inside edges. Installed in the nose cover is a fixed landing 
light. The nose cover is attached to the cabin framework by stud 
fasteners. Removal of the nose cover provides access to the landing 
light, instrument connections, components of the cabin heating and 
ventilation system, and the windshield wiper motor. 
Forward Access Cover 
The forward access cover is a sandwich construction made out of 
carbon and glassfiber prepreg with NOMEX® core, which is attached 
to the lower shell by stud fasteners. When the stud fasteners are 
opened, the forward access cover hangs from the lower shell by 
means of four cables with snap hooks on their ends which clip onto 
brackets on the forward access cover and the lower shell. Removal of 
the forward access cover provides access to flight control components 
and to the blower of the cabin heating and ventilation system. 
Middle Cover 
The middle cover is of aluminum sheet metal construction. It is 
attached to the lower shell bymeans of stud fasteners. Removal of the 
middle cover provides access to flight control components and to the 
engine emergency flexball cable. 
For helicopters equipped with a cargo hook the middle cover is fitted 
with a hood. A hood is attached to the cover to provide access to 
components of the cargo hook. 
Tank Covers 
Two main tank covers are constructed of aluminum sheet metal. They 
are provided with a protective plastic edging. Each cover has a round 
opening in which the boot of the associated fuel drain valve is inserted. 
The covers are attached by screws to the lower shell. Removal of the 
covers provides access to the equipment plates of the fuel system. 
The supply tank cover is constructed of aluminum sheet metal. It has 
two round holes in which the boots of the fuel drain valves are inserted. 
The cover is attached by screws to the lower shell. Removal of the 
cover provides access to the two equipment plates of the fuel system. 
Tail Boom Covers 
The RH and LH tail boom covers are made of carbon, glass hybrid 
prepreg. They are attached by screws to the tail boom. Removal 
of the covers provides access to the antenna connections, wiring 
harnesses and the magnetometers. The lower and aft vertical fin 
covers are of composite construction. They are attached by screws to 
the Fenestron® structure. Removal of the covers provides access to 
the inside of the Fenestron® structure for inspection purposes.
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EC135 Classic 
B1 
Training Manual
03 – 27Iss. August 2018Forinstruction only
Service Covers
03 – Fuselage
3.7 Service Covers
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03 – Fuselage
3.8 Windows
3.6.3 Rear Doors
EC135 Classic 
B1 
Training Manual
03 – 28Iss. August 2018For instruction only
3.8 Windows
Windshields
The windshields are made of 5 mm thick acrylic glass. Optional 
windshields with a hard, scratch-resistant surface coating are also 
provided. The windshields are positioned on a formed sealing strip and 
a layer of adhesive sealant in the cabin framework and secured to the 
latter by countersunk screws, dimpled washers and sealing washers. 
The bottom edge of the windshields is not attached by screws to the 
cabin framework, but is held against it by a metal retaining strip. A 
metal strip is installed between the windshields, which is attached by 
screws to the center post of the cabin framework. It is installed flush 
with the adjacent windshields to provide a flat, continuous surface for 
the windshield wiper. The joint between the windshields and the cabin 
framework is not rigid but designed to give the windshields a limited 
degree ofmovement relative to the cabin framework. In consequence:
 – varying degrees of heat expansion in the cabin framework 
and the windshields are compensated and 
 – stresses imposed on the windshields due to deformation of 
the cabin framework are prevented.
For this purpose, the diameter of the washer holes is bigger than the 
shank diameter of the mating countersunk screws.
Nose Windows
The nose windows are made of 2 mm thick acrylic glass and reinforced 
with 1 mm thick Orlon around the edges. They are positioned on 
a formed sealing strip and a layer of adhesive sealant in the cabin 
framework and secured to the latter by countersunk screws and 
dimpled washers. The upper edge of the nose windows is not attached 
by screws to the nose spar, but is held against it by a metal retaining 
strip which itself is attached by screws to the nose spar.
Side Windows 
The side windows are made of 2 mm thick acrylic glass. They are 
positioned on a layer of adhesive sealant in the side panels and 
secured to the latter by round–head screws and washers. 
Cleaning of the Windows
♦ NOTE Use only approved cleaning agents. Unapproved 
cleaning agents may contain harmful solvents that 
could cause crazing.
♦ NOTE Scratches can be polished out using approved 
polishing paste. This is not applicable if the 
windshields are hardcoated.
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EC135 Classic 
B1 
Training Manual
03 – 29Iss. August 2018For instruction only
Windshield, Nose and Side Windows
03 – Fuselage
3.8 Windows
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03 – Fuselage
3.9 Cowling
3.6.3 Rear Doors
EC135 Classic 
B1 
Training Manual
03 – 30Iss. August 2018For instruction only
3.9 Cowling
General
The cowling covers the areas above the hydraulic, transmission and 
engine deck and further the equipment deck. 
Material 
The cowlings are a sandwich design with a NOMEX®core and a 
hybrid carbon-, glass- and polyester prepreg fabric.
Components 
The cowlings consist of several components, which can be removed 
individually. It comprises:
 – LH and RH side transmission cowling 
 – LH and RH side engine cowling 
 – LH and RH side AFT cowling.
Access Doors and Access Panels
Access doors are provided to ease maintenance and inspections.
Fire Protection
The hot section of the cowling interior is protected with fire retarding 
paint. Together with the fire walls they build a fire resistant cell around 
each engine.
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EC135 Classic 
B1 
Training Manual
03 – 31Iss. August 2018For instruction only
Cowlings
03 – Fuselage
3.9 Cowling
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03 – Fuselage
3.10 Placards and Markings
3.10.1 General 
EC135 Classic 
B1 
Training Manual
03 – 32Iss. August 2018For instruction only
3.10 Placards and Markings
3.10.1 General 
Every placard, label and marking is important. Some placards, labels 
and markings are mandatory installations as determined by local 
government regulations and local airworthiness regulations. There 
are exterior and interior placards, labes and markings 
3.10.1.1 Component Locations
For all the illustrations and locations of each of the placards, labels 
and markings that are installed on the exterior and interior of the 
helicopter, refer to the Illustrated Parts Catalog (IPC), Chapter 11. 
♦ NOTE As all maintenance tasks, the installation of placards 
has to be done by technical certifying staff only 
i.a.w. related MM, ATA 11.
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EC135 Classic 
B1 
Training Manual
03 – 33Iss. August 2018For instruction only
Placards, Labels and Markings; Examples
03 – Fuselage
3.10 Placards and Markings
3.10.1 General 
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34
03 – 
INTENTIONALLy LEFT BLANK
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1
EC135 Classic 
B1 
Training Manual
04 – 1Iss. August 2018For instruction only
04 – Tail Unit
Chapter 04
Tail Unit
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2
EC135 Classic 
B1 
Training Manual
04 – 2Iss. August 2018For instruction only
Table of contents
4.1 Principle of the Fenestron® ............................................ 4
4.2 Tail Unit ............................................................................. 6
4.2.1 General .............................................................................. 6
4.2.2 Horizontal Stabilizer ........................................................... 8
4.2.3 Tail Boom ......................................................................... 10
4.2.4 Tail Rotor Drive ................................................................ 14
4.2.5 Forward and Aft Drive Shaft ............................................. 16
4.2.6 Fenestron® Structure ...................................................... 18
4.2.7 Tail Rotor Gearbox ........................................................... 20
4.2.8 Input Drive Flange ........................................................... 22
4.2.9 Oil System ....................................................................... 24
4.2.10 TRGB CHIP Caution ........................................................ 24
4.2.11 Tail Rotor .......................................................................... 26
4.2.12 Components .................................................................... 28
4.2.13 Pitch Change Spider ........................................................ 30
This training document comprises the following ATA chapters:
Principle of the Fenestron® ATA 53
Tail Unit ATA 53
Horizontal Stabilizer ATA 53
Tail Boom ATA 53
Tail Rotor Drive ATA 65
Forward and Aft Drive Shaft ATA 65
Fenestron® Structure ATA 53
Tail Rotor Gearbox ATA 65
Input Drive Flange ATA 65
Oil System ATA 65
Tail Rotor ATA 64
Pitch Change Spider ATA 64
04 – Tail Unit
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3
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EC135 Classic
B1
Training Manual04 – Tail Unit
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4
EC135 Classic 
B1 
Training Manual
04 – 4Iss. August 2018For instruction only
04 – Tail Unit
4.1 Principle of the Fenestron®
4.1 Principle of the Fenestron®
General
The counterclockwise sense of rotation of the main rotor results in a 
clockwise torque acting on the main gear box and the fuselage. 
Thus in hover or in flight with low forward speed the helicopter nose 
tends to turn to the right. To counteract this movement the tail rotor 
thrust has to keep the H/C nose straight by creating a force on the 
tailboom to the right with the airflow from right to left. 
With higher forward speeds flying straight and level, the power demand 
for the tail rotor decreases significantly due to the aerodynamic shape 
of the vertical fin and the angle between endplates and the flight 
direction (leading egde pointing to the right).
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EC135 Classic 
B1 
Training Manual
04 – 5Iss. August 2018For instruction only
Principle of the Fenestron®
04 – Tail Unit
4.1 Principle of the Fenestron®
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04 – Tail Unit
4.2 Tail Unit
4.2.1 General
EC135 Classic 
B1 
Training Manual
04 – 6Iss. August 2018For instruction only
4.2 Tail Unit
4.2.1 General
The rear structure is the aft section of the fuselage. It stabilizes the 
helicopter in flight by means of the vertical fin with the integrated 
Fenestron® tail rotor. It also provides the lever arm on which the thrust 
of the tail rotor counteracts the torque of the main rotor system. The 
rear structure is a sandwich design made out of carbon, glass hybrid 
preprag with NOMEX® core inside.
Components
The rear structure of the EC 135 consists of the following assemblies:
 – tail boom
 – horizontal stabilizer 
 – Fenestron® structure.
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EC135 Classic 
B1 
Training Manual
04 – 7Iss. August 2018For instruction only
Rear Structure up to P2+ / T2+
04 – Tail Unit
4.2 Tail Unit
4.2.1 General
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04 – Tail Unit
4.2 Tail Unit
4.2.2 Horizontal Stabilizer
EC135 Classic 
B1 
Training Manual
04 – 8Iss. August 2018For instruction only
4.2.2 Horizontal Stabilizer
General
The horizontal stabilizer aerodynamically steadies the helicopter 
around the lateral axis during forward flight. The horizontal stabilizer 
has an asymmetric negative profile which creates downforce to 
compensate the pitch motion of the helicopter. The pitch angle is a 
permanent setting and is not adjustable.
Design
The horizontal stabilizer passes through the tail boom. It is attached 
by one bolt on each side which connects the stabilizer with the 
attachment brackets that are intergrated into the tail boom. 
The horizontal stabilizer is a shell-type structure made of carbon 
and glass fiber-reinforced plastic, which is partially reinforced with 
NOMEX® cores.
Up to and including P2 / T2, P2+ / T2+
An end plate is attached by 6 screws to each outboard end of the 
horizontal stabilizer. It is a honeycomb sandwich construction, made 
out of carbon and glasfiber prepreg material with NOMEX® cores. 
When viewed in the direction of flight, the end plates are permanently 
offset to the right, thereby reducing the power required by the tail rotor 
system in cruise flight. 
Fitted to the outboard sides of the end plates are the position lights. 
For easy removal and installation, the two parts of the flaps are bolted 
on the RH side while riveted only on the LH side.
P3 / T3
On each end the stabilizer is closed by a glassfibre cover. These 
covers are attached by 6 screws and are equipped with the position 
lights. To allow the horizontal stabilizer to pass through the tail boom 
the end covers need to be removed. 
Spoilers are installed on the upper part of the stabilizer. For removal 
and installation, it is not necessary to remove the flaps.
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EC135 Classic 
B1 
Training Manual
04 – 9Iss. August 2018For instruction only
Horizontal Stabilizer and End Plates
04 – Tail Unit
4.2.2 Horizontal Stabilizer
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04 – Tail Unit
4.2 Tail Unit
4.2.3 Tail Boom
EC135 Classic 
B1 
Training Manual
04 – 10Iss. August 2018For instruction only
4.2.3 Tail Boom
General
The tail boom connects the rear structure to the main fuselage 
structure. It supports the vertical fin, tail rotor system and the horizontal 
stabilizer. The tail rotor drive shaft, hydraulic lines and the tail rotor flex 
ball control run along the top of the tail boom.
Design
The tail boom is a sandwich structure consisting of a NOMEX® core 
with carbon / glass hybrid preprag fiber skin, in which a copper foil is 
embedded to ensure electrical conductivity. 
The conically–shaped tail boom is built up of two half sections joined 
by bonding and additionally secured by rivets. The aluminum–alloy 
connecting frame is riveted to the inside of the tail boom. To prevent 
corrosion, the mating surfaces are isolated from each other by layers 
of sealing compound. When installing the tail boom, the mating 
surfaces have to be free of paint and grease. The tail boom is bolted 
to the connecting frame 8 of the main fuselage structure through its 
connecting frame.
Fittings
In the areaswhere the fittings are installed, the half sections are locally 
reinforced. The aft end of the tail boom is provided with two cutouts 
with integral fittings for attaching the horizontal stabilizer. Bolted at 
intervals along the top of the tail boom are five bearing supports 
for supporting the tail rotor drive shaft. The first three brackets are 
supported by vertical struts in the structure in order to stabilize the 
entire system. 
Access to the interior of the tail boom is provided by maintenance 
covers. Cable ducts for the electrical cables are routed inside the tail 
boom. 
When communication/navigation systems such as the VHF, VOR, 
ADF, and radar altimeter (optional equipment) are installed, the tail 
boom is fitted with antenna connections which the respective antennas 
are installed to.
Fairing
A detachable fairing made of carbon, glas hybrid preprag material, 
provides a covering for the tail rotor drive shaft, hydraulic lines, and the 
Flexball control cable. The fairing is fitted by spring-loaded fasteners 
to the tail boom. 
On the connecting frame, a bulkhead plate is attached.
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EC135 Classic 
B1 
Training Manual
04 – 11Iss. August 2018For instruction only
Tail Boom
04 – Tail Unit
4.2.3 Tail Boom
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EC135 Classic 
B1 
Training Manual
04 – 12Iss. August 2018For instruction only
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04 – Tail Unit
4.2.3 Tail Boom
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EC135 Classic 
B1 
Training Manual
04 – 13Iss. August 2018For instruction only
Tail Boom
04 – Tail Unit
4.2.3 Tail Boom
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4.2 Tail Unit
4.2.4 Tail Rotor Drive
EC135 Classic 
B1 
Training Manual
04 – 14Iss. August 2018For instruction only
4.2.4 Tail Rotor Drive
General
The tail rotor drive transmits the power from the main rotor transmission 
to the tail rotor through a system of shafts, flexible couplings and the 
tail rotor gearbox.
Components
The tail rotor drive train consists of the following parts:
 – 3 shafts with flexible couplings
 – tail rotor gearbox.
Drive Shafts
The tail rotor drive shaft assembly consists of:
 – forward drive shaft with two couplings
 – center drive shaft with six bearings
 – aft drive shaft with two couplings.
♦ NOTE There is no mechanical or electrical notification in 
the event that the tail rotor drive fails.
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EC135 Classic 
B1 
Training Manual
04 – 15Iss. August 2018For instruction only
Tail Rotor Drive Shaft
04 – Tail Unit
4.2.4 Tail Rotor Drive
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04 – Tail Unit
4.2 Tail Unit
4.2.5 Forward and Aft Drive Shaft
EC135 Classic 
B1 
Training Manual
04 – 16Iss. August 2018For instruction only
4.2.5 Forward and Aft Drive Shaft
The forward and aft drive shafts are built up as follows:
 – tube
 – flanges
 – flexible couplings.
The tubes consist of carbon fiber. The three–armed flanges consist of 
titanium and are riveted and bonded to the ends of the tubes. 
The forward drive shaft is connected via the flexible couplings and 
flanged couplings to the tail rotor output drive of the main transmission 
and to the center drive shaft. 
The aft drive shaft is connected via flexible couplings directly to the 
center drive shaft and to the tail gearbox input flange. 
Due to the rear flange which protrudes more from the shaft than the 
forward one, the aft drive shaft can only be installed in one direction.
Flexible Coupling
The flexible couplings consist of packs of steel discs which are held 
together by assembled flanged sleeves and washers. The flexible 
couplings correct misalignment and variations in length.
Center Drive Shaft
The center drive shaft is built up as follows:
 – tube
 – two removeable flanges
 – 6 ball bearings with rubber sleeves.
The tube consists of steel. The bolted and the removable flanges 
consist of titanium. 
The removable flanges are connected to the tube by spring bushings 
which are secured by bolts, nuts and special washers. 
The center drive shaft is supported by six sealed ball bearings which 
are mounted on top of the tail boom by bearing supports. The inner 
races of the bearings are embedded in rubber sleeves which help to 
dampen vibrations and account for misalignment. 
If there is fretting of a bearing, the drive shaft can keep on turning 
because of the rubber sleeve (there will be discoloring and abrasion).
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EC135 Classic 
B1 
Training Manual
04 – 17Iss. August 2018For instruction only
Drive Shafts
04 – Tail Unit
4.2.5 Forward and Aft Drive Shaft
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04 – Tail Unit
4.2 Tail Unit
4.2.6 Fenestron® Structure
EC135 Classic 
B1 
Training Manual
04 – 18Iss. August 2018For instruction only
4.2.6 Fenestron® Structure
General
The Fenestron® structure consists of the vertical fin and the tail rotor 
shroud. The vertical fin has an aerodynamic function while the tail 
rotor shroud underneath encloses the tail rotor system. By reaching 
an airspeed around 50 KIAS the vertical fin generates sufficient force 
to counteract the moment produced by the main rotor. Therefore less 
power is needed at the tail rotor.
Design
The vertical fin is constructed of Nomex® honeycomb with carbon and 
glas hybrid prepreg fiber-reinforced facings. Embedded in the outer 
facing plies, there is a copper foil which ensures electrical conductivity. 
The vertical fin is built up of two half sections joined together by bonding 
and riveting. It is riveted to the tail boom via a connecting flange. 
A fin tip fairing, which incorporates the anti-collision light, is screwed 
to the open upper end of the vertical fin.
Up to and including P2+ / T2+
Screwed to the underside of the Fenestron® airframe, there is a tail 
bumper which increases the yaw stability and protects the tail boom 
against impacts, e.g. ground contact during flare. A static discharger 
is fitted at the fin tip fairing as well as at the tail bumber.
P3 / T3
To increase the aerodynamic efficiency a Gurney flap is attached to 
the left side of the vertical fin. 
Screwed to the underside of the Fenestron® airframe is a tail bumper, 
which increases the yaw stability. This bumper also protects the 
tail boom against impacts, e.g. ground contact during flare. A static 
discharger is fitted at the fin tip fairing.
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EC135 Classic 
B1 
Training Manual
04 – 19Iss. August 2018For instruction only
Vertical Fin with Fenestron®
04 – Tail Unit
4.2.6 Fenestron® Structure
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04 – Tail Unit
4.2 Tail Unit
4.2.7 Tail Rotor Gearbox
EC135 Classic 
B1 
Training Manual
04 – 20Iss. August 2018For instruction only
4.2.7 Tail Rotor Gearbox
General
The tail rotor gearbox is a single-stage, spiral-toothed bevel gear. Its 
purpose is to:
 – drive the tail rotor
 – reduce the speed from the drive shafts
 – divert the direction of power flow through 90° by means of 
two bevel gears
 – transmit tail rotor forces and moments through the stator to 
the fuselage.
The tail rotor gearbox houses the components which control the tail 
rotor. These components transmit the control inputs from non rotating 
to the rotating parts of the tail rotor.
Components
The tail rotor gearbox consists of the following:
 – gearbox housing
 – input casing 
 – output casing 
 – input drive flange
 – input pinion gear 
 – output gear wheel 
 – control unit (comprising casing, control rod, guide).
Tab. 04-1: Leading Particulars Tail Rotor Gearbox
Mass incl. oil approx. 8.5 kg = approx. 19 lb
Gear ratio 0.72
Speed drive 4986 rpm
Speed output 3584 rpm
Oil quantity approx. 0.5 l
Oil Types
MIL-L-6086 C; O-155 
MIL-PRF-23699; O-156 
Air Go 3001; “Transmax Z”
Material Aluminum alloy
Design / Function
The gearbox housing is made of aluminum alloy. Installed in the 
housing there are the input pinion gear and output gear wheel which 
are attached by the flanges of their supporting bearing outer races to 
the gearbox housing. The gearbox housing is provided with an input 
casing and an output drive casing which are both fitted with a shaft 
seal.
TRGB CHIP Caution
For the detection of magnetic chips in the oil system, a chip detector 
is installed by a bayonet connection in the TRGB oil drain valve (the 
check valve closes when the chip detector is removed).
Accumulation of particles bridge a contact gap of the detector magnet 
and they complete the circuit to the CDS / CPDS. The indication at the 
MISC CAUTION display will be:
 – TRGB CHIP
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EC135 Classic 
B1 
Training Manual
04 – 21Iss. August 2018For instruction only
Tail Rotor Gearbox
04 – Tail Unit
4.2.7 Tail Rotor Gearbox
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04 – Tail Unit
4.2 Tail Unit
4.2.8 Input Drive FlangeEC135 Classic 
B1 
Training Manual
04 – 22Iss. August 2018For instruction only
4.2.8 Input Drive Flange
The input drive flange, which transmits torque to the input pinion gear, 
is formed with a three–arm flange and a splined shaft which meshes 
with the internal splines of the input pinion gear.
Input Pinion Gear
The input pinion gear, which drives the output gear wheel, consists of 
a spiral bevel gear, a double ball bearing, and a special nut secured 
by a locking ring.
Output Gear Wheel
The output gear wheel, which drives the tail rotor, consists of a spiral 
pinion gear, a double ball bearing and a special nut secured by a 
locking ring. The tail rotor is splined to the pinion of the output gear 
wheel through the splined hub flange.
Control Unit
The casing, control rod and guide house the control unit which is 
installed inside the output gear wheel. Control inputs cause the 
Fenestron® actuator to move the contol unit in an axial direction. The 
control unit transfers control movements to the tail rotor. 
The control unit casing comprises the casing itself and an integrated 
control rod which is connected to the input lever of the tail rotor control 
linkage so that the casing cannot rotate. 
Installed inside the casing, there is a control rod and a double ball 
bearing which is held in the housing by a special nut and secured by 
a nut retainer. 
The components inside the casing provide the transition from the non-
rotating parts to rotating parts of the tail rotor controls. 
The axial movement of the control unit casing is transferred through 
the double ball bearing to the rotating control rod and guide. The 
control rod and guide are connected to the tail rotor blades through 
the center flange and the pitch change spider of the tail rotor, causing 
them to rotate at the same speed as the tail rotor. 
A setting shim is interposed between the guide and the central flange. 
The thickness of the setting shim determines the position of the central 
flange and, when adjusted, affects the pitch of the tail rotor blades.
♦ NOTE The adjustment of the boosted part of the tail rotor 
control is done with the help of this setting shim.
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EC135 Classic 
B1 
Training Manual
04 – 23Iss. August 2018For instruction only
Tail Rotor Gearbox
04 – Tail Unit
4.2.8 Input Drive Flange
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04 – Tail Unit
4.2 Tail Unit
4.2.9 Oil System
EC135 Classic 
B1 
Training Manual
04 – 24Iss. August 2018For instruction only
4.2.9 Oil System
The lubrication of the tail rotor gearbox is ensured by a splash 
lubrication (wet sump) system.
Installed in the lower portion of the gearbox housing is a drain valve 
with a chip detector that also serves as plug. When the chip detector is 
removed an oil drain hose with an adapter can be temporarily installed 
in its place to drain the oil from the gearbox.
An oil level sight glass, which has minimum and maximum markings, 
enables visual inspection of the oil level. 
The oil filler neck of the gearbox housing is fitted with a strainer and 
a cap. 
The tail rotor gearbox is cooled by the circulating oil and via the 
gearbox housing.
4.2.10 TRGB CHIP Caution
For the detection of magnetic chips in the oil system, a chip detector 
is installed by a bayonet connection in the TRGB oil drain valve (the 
check valve closes when the chip detector is removed).
Accumulation of particles bridge a contact gap of the detector magnet 
and they complete the circuit to the CDS / CPDS. The indication at the 
MISC CAUTION display will be:
 – TRGB CHIP
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EC135 Classic 
B1 
Training Manual
04 – 25Iss. August 2018For instruction only
Tail Rotor Gearbox
04 – Tail Unit
4.2.10 TRGB CHIP Caution
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04 – Tail Unit
4.2 Tail Unit
4.2.11 Tail Rotor
EC135 Classic 
B1 
Training Manual
04 – 26Iss. August 2018For instruction only
4.2.11 Tail Rotor
General
The tail rotor is a shrouded fan–in–fin rotor (Fenestron® concept) 
which is installed in a duct in the Fenestron® structure. It is installed 
on the RH side of the helicopter. 
It performs the following functions:
 – counteracts main rotor torque 
 – controls the helicopter around the yaw axis.
The tail rotor generates the thrust required to counteract main rotor 
torque. This is achieved by changing the pitch angle of the tail rotor 
blades. The direction of rotation of the tail rotor is counterclockwise 
when viewed head–on from the right-hand side of the helicopter. 
The tail rotor is equipped with ten unevenly–spaced rotor blades. This 
arrangement produces overlapping of the acoustic vibrations, thereby 
providing a lower tail rotor noise level. 
A stator is installed in the duct of the Fenestron® structure. The stator 
consists of the stator hub and inclined vanes. The vanes straighten the 
airflow generated by the tail rotor, thereby improving its efficiency and 
keeping the noise level low through the inclined installation. Attached 
to the stator hub is the tail rotor gearbox. The tail rotor and the tail rotor 
gearbox are connected to each other through the splined hub flange 
and the output gear wheel.
Tab. 04-2: Leading Particulars Tail Rotor
Weight incl. blades 8.2 kg (18 lb)
Nominal speed 3584 rpm
Power required max 110 - 120 kW
Rotation
counterclockwise 
(viewed head–on from starboard 
of helicopter)
Weight of one blade approx. 0.29 kg (0.64 lb)
Quantity 10 off
Material Aluminum alloy
Profile nonlinear airfoil, spanwise twist
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EC135 Classic 
B1 
Training Manual
04 – 27Iss. August 2018For instruction only
Principle of Tail Rotor
04 – Tail Unit
4.2.11 Tail Rotor
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04 – Tail Unit
4.2 Tail Unit
4.2.12 Components
EC135 Classic 
B1 
Training Manual
04 – 28Iss. August 2018For instruction only
4.2.12 Components
The tail rotor consists of the following:
 – 10 tail rotor blades
 – hub body 
 – 10 inner bearings 
 – 10 outer bearings 
 – pitch change spider 
 – center flange
 – fairing.
Tail Rotor Blades
The tail rotor blades are constructed of aluminum alloy and consist 
of the blade air foil and the blade root. The tail rotor blade air foil is 
formed with a built–in spanwise twist. It has a nonlinear profile which 
progressively changes from the blade neck to the root. The blade 
root is hollow. It has two bearing surfaces and, a bore hole for two 
bushings and the blade bolt, and a pitch horn. The tail rotor blades 
are supported in the hub body by the bearing rings. This arrangement 
enables the tail rotor blades to change their pitch angles. Bolted to the 
pitch horn is a ball segment which connects the tail rotor blade to the 
pitch change spider. The hollow blade root serves to accomodate the 
tension-torsion bar to which the rotor blade is attached by bushings 
and a blade bolt.
Fairing
A fairing protects the components within the hub body and is fitted with 
fasteners. At the center of the fairing is a bore which is used to detach 
the fairing. The bore is sealed by a plug.
Thrust Nut
The thrust nut is screwed to the output gear wheel of the tail rotor 
gearbox and secures the tail rotor. It is prevented from rotating by 
the locking washer. The thrust nut transmits the tail rotor thrust to the 
Fenestron® structure through the tail rotor gearbox and the stator.
The thrust nut is only hand tightened.♦ NOTE The contact position of the tail rotor on the output 
gear wheel is ensured by four thrust screws. The 
screws pass through locking washer and thrust nut 
and push on the attach ring.
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EC135 Classic 
B1 
Training Manual
04 – 29Iss. August 2018For instruction only
Tail Rotor
04 – Tail Unit
4.2.12 Components
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04 – Tail Unit
4.2 Tail Unit
4.2.13 Pitch Change Spider
EC135 Classic 
B1 
Training Manual
04 – 30Iss. August 2018For instruction only
4.2.13 Pitch Change Spider
The pitch change spider is attached to the pitch horn of the tail rotor 
blades through ball joints. It is the central pitch changing component 
for all tail rotor blades.
Center Flange
The center flange is bolted to the pitch change spider and is connected 
to the control rod and guide of the tail rotor gearbox. Interposed 
between the guide in the tail rotor gear box and the center flange is a 
setting shim by means of which the pitch of the tail rotor blades can 
be set. 
Control inputs move the control rod and the guide, which in turn move 
the pitch change spider axially through the interconnected center 
flange. Simultaneously, the pitch angle of all the blades is changed 
by the same amount via the pitch horns mounted on the pitch change 
spider.
Propeller Moment Weights
The propeller moment weights dynamically reduce the control forces. 
Propeller moment weights are also called chinese weights.
♦ NOTE There are two propeller moment weights mounted 
to each blade.
Hub Body with Bearings
The hub body houses the tail rotor components. In the hub body, the 
tail rotor blades are each supported in an outer and an inner bearing. 
On the hub body rear side 6 threads for bolts and balance washers 
are installed.
♦ NOTE For balancing work these bolts have to be numbered 
from 1 to 6 beginning at the soft iron plate in counter–
clockwise direction.
Splined Hub Flange
The splined hub flange is connected to the hub body by screws and, 
through its internal spline, is splined to the pinion of the output gear 
wheel. It connects the tail rotor to the tail rotor gear box.
Tension–torsion Bar 
The tension–torsion bar consists of a pack of steel laminates which 
are held together by a shrinking hose. The tension-torsion bars retain 
the tail rotor blades within the hub body and connect them to the hub 
flange. The tension–torsion bar absorb centrifugal forces. The low 
torsional stiffnes of its steel laminates enables pitch angle variation on 
all the tail rotor blades. 
Attach Ring 
The attach ring together with the tension-torsion bars and the hub 
flange are attached to the hub body by bolts and associated nuts.
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EC135 Classic 
B1 
Training Manual
04 – 31Iss. August 2018For instruction only
Tail Rotor Control
04 – Tail Unit
4.2.13 Pitch Change Spider
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EC135 Classic 
B1 
Training Manual
04 – 32Iss. August 2018For instruction only
INTENTIONALLy LEFT BLANK
04 – Tail Unit
4.2.13 Pitch Change Spider
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EC135 Classic 
B1 
Training Manual
04 – 33Iss. August 2018For instruction only
Tail Rotor Control
04 – Tail Unit
4.2.13 Pitch Change Spider
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34
04 – 
INTENTIONALLy LEFT BLANK
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1
EC135 Classic 
B1 
Training Manual
05 – 1Iss. August 2018For instruction only
05 – Flight Control
Chapter 05
Flight Control
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2
EC135 Classic 
B1 
Training Manual
05 – 2Iss. August 2018For instruction only
Table of contents
5.1 Principle of the Flight Control ........................................ 4
5.2 Flight Control of the EC135 ............................................ 6
5.2.1 Components ...................................................................... 6
5.2.2 Collective Control ............................................................... 8
5.2.3 Transmission of Control Signals ...................................... 10
5.2.4 Weight Compensation ..................................................... 14
5.2.5 Cyclic Control ................................................................... 16
5.2.6 Cyclic Centering Device ................................................... 18
5.2.7 Mixing Lever Assembly .................................................... 20
5.2.8 Mixing Lever Assembly P3/T3 Version ............................ 22
5.2.9 Rotating Control Rods P3/T3 Version .............................. 24
5.2.10 Adjustment Boosted Section P3/T3 Version .................... 24
5.2.11 Principle of the Transmission of Control Signals ............. 26
5.2.12 Swash Plate ..................................................................... 28
5.2.13 Rotating Control Rod ....................................................... 30
5.2.14 Scissors Assembly ........................................................... 32
5.2.15 Trim System ..................................................................... 34
5.3 Tail Rotor Control .......................................................... 40
5.3.1 Components ................................................................... 40
5.3.2 Function of the Tail Rotor Control .................................... 42
5.4 Hydraulic System ........................................................... 44
5.4.1 Components .................................................................... 44
5.4.2 Location ........................................................................... 44
5.4.3 Redundancy Provision ..................................................... 46
5.5 Indication and Testing Systems ................................... 48
5.5.1 Pressure Supply Systems ................................................ 50
5.5.2 Reservoir ......................................................................... 54
5.5.3 Hydraulic Valve Block - Normal Operation ....................... 56
5.6 Hydraulic Actuators ....................................................... 58
5.6.1 Assembly ......................................................................... 58
5.6.2 Description of the Follow-up Principle ............................. 58
5.7 Mechano-Hydraulic Actuator MHA ............................... 62
5.7.1 Assembly ......................................................................... 62
5.7.2 Function ........................................................................... 62
5.7.3 Mechanical Override ........................................................ 64
5.7.4 System Test ..................................................................... 66
5.8 Electro-Hydraulic Actuator EHA ................................... 68
5.8.1 Function ........................................................................... 68
5.9 Fenestron® Actuator ..................................................... 70
5.9.1 Function .......................................................................... 70
5.10 Three Axis Stability Augmentation System SAS ........ 72
5.10.1 Yaw Stability Augmentation System ................................ 74
5.10.2 Fiber Optical Gyro FOG ...................................................76
5.10.3 Pitch & Roll Stability Augmentation System ..................... 78
5.10.4 Circuit Breaker Roll SAS and Pitch SAS (AC System) .... 80
5.10.5 Pitch Damper (DPIFR) ..................................................... 82
05 – Flight Control
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05 – Flight Control EC135 Classic 
B1 
Training Manual
05 – 3Iss. August 2018For instruction only
5.11 Autopilot System EC135 ............................................... 84
5.11.1 Installation Locations ....................................................... 86
5.11.2 EHA .................................................................................. 88
This training document comprises the following ATA chapters:
Principle of the Flight Control ATA 67
Flight Control of the EC135 ATA 67
Tail Rotor Control ATA 67
Hydraulic System ATA 29
Indication and Testing Systems ATA 29
Hydraulic Actuators ATA 67
Mechano-Hydraulic Actuator MHA ATA 67
Electro-Hydraulic Actuator EHA ATA 67
Fenestron® Actuator ATA 67
Three Axis Stability Augmentation System SAS ATA 22
Autopilot System EC135 ATA 22
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4
EC135 Classic 
B1 
Training Manual
05 – 4Iss. August 2018For instruction only
05 – Flight Control
5.1 Principle of the Flight Control
5.1 Principle of the Flight Control
General
The attitude and airspeed of the EC135 are controlled by adjusting the 
angle of incidence of the main and tail rotor blades.
Flight Control
Three types of controls are necessary to fly the helicopter:
 – collective control of the main rotor
 – cyclic control of the main rotor
 – tail rotor control.
The pilot gives control signals by:
 – collective pitch lever (left hand)
 – cyclic control stick (right hand)
 – tail rotor pedals (feet).
Collective Control
Changing the angle of incidence equally on all four main rotor blades 
increases or decreases the main rotor thrust. This is called collective 
control.
Cyclic Control
The cyclic control adjusts the angle of incidence of two opposite blades 
periodically and inverse. By means of this results a horizontal force. 
The helicopter will tilt and move in the direction of the horizontal force. 
Cyclic control consists of lateral control (left and right movement) and 
longitudinal control (forward and backward movement).
Tail Rotor Control
The tail rotor control is in principle the same as the collective control 
of the main rotor system. Adjusting the angle of incidence of the ten 
tail rotor blades collectively varies the thrust, reacting against themain 
rotor torque. If these forces are equal, the helicopter stands still in 
hover. If not, the helicopter will turn around its yaw axis.
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EC135 Classic 
B1 
Training Manual
05 – 5Iss. August 2018For instruction only
Flight Control
05 – Flight Control
5.1 Principle of the Flight Control
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.1 Components
EC135 Classic 
B1 
Training Manual
05 – 6Iss. August 2018For instruction only
5.2 Flight Control of the EC135
5.2.1 Components
The flight control of the EC135 comprises the following systems:
 – main rotor control
 – tail rotor control.
5.2.1.1 Main Rotor Control
The main rotor control conists of two systems:
 – collective control
 – cyclic control.
5.2.1.2 Components
The most important components of the main rotor control are:
 – collective lever
 – cyclic stick 
 – trim system
 – control linkage, non boosted section 
 – one mechano-hydraulic actuator (MHA)
 – two electro-hydraulic actuators (EHA)
 – mixing lever assembly
 – control rods, boosted section.
5.2.1.3 Tail Rotor Control
The main components of the tail rotor control are:
 – pedal assembly
 – Flexball control cable
 – yaw SAS actuator (SEMA)
 – Fenestron® actuator.
5.2.1.4 Color Code
The parts of the control linkages are color coded:
 – red: right side, roll axis
 – white: center, collective
 – black: left side, pitch axis
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EC135 Classic 
B1 
Training Manual
05 – 7Iss. August 2018For instruction only
Flight Control
05 – Flight Control
5.2 Flight Control of the EC135
5.2.1 Components
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.2 Collective Control
EC135 Classic 
B1 
Training Manual
05 – 8Iss. August 2018For instruction only
5.2.2 Collective Control
5.2.2.1 Signal Input
The collective control signals are given by pulling the collective pitch 
lever upward or pushing downward. Pulling creates climb, pushing 
descent.
5.2.2.2 Collective Pitch Lever
The collective pitch lever is located on the left side of the pilot seat. 
The second lever is located on the left side of the copilot seat. Both 
collective pitch levers are mechanically linked via a torsion tube.
5.2.2.3 Friction Brake
To prevent PIO’s and undesired movement of the collective lever 
during flight, a friction brake acts on the torsion tube. The desired 
friction against the movement of the pitch lever can be set by the 
adjusting screw.
5.2.2.4 Collective Pitch Stop
The collective pitch stop is an elastic stop which limits the angle of 
attack of the main rotor blades in fast and high density altitude flights.
During an emergency condition i.e. autorotation landing it may be 
necessary to exceed this elastic stop. This will increase the collective 
control force because of a spring force to overcome.
♦ NOTE Final adjustment of the collective pitch stop is 
determined during maintenance check flight. The 
actual mechanical stop is compared to the rotor 
thrust given by the measured torque under the 
respective outside air conditions (PA, OAT). If there 
is a difference to the calculated value in the diagram, 
the mechanical stop can be adjusted by changing 
the number of shims under the pitch stop flange. 
(approx. 1 % TRQ per 0.15 mm shim thickness).
♦ NOTE The adjusted friction force must not be below the 
given minimum in the AMM to avoid PIOs.
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EC135 Classic 
B1 
Training Manual
05 – 9Iss. August 2018For instruction only
Collective Shaft
05 – Flight Control
5.2.2 Collective Control
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.3 Transmission of Control Signals
EC135 Classic 
B1 
Training Manual
05 – 10Iss. August 2018For instruction only
5.2.3 Transmission of Control Signals
The control signals are transmitted via the collective shaft, located 
underneath the cockpit floor, several control rods and bell cranks 
to the input control lever of the dual hydraulic boost unit. Here, the 
signals are force amplified. The amplified signals are transmitted via 
a control rod to the collective control fork, which is part of themixing 
lever assembly. The collective control fork lowers or lifts the sliding 
sleeve, which creates the intended simultaneous variation of the angle 
of incidence on all four rotor blades.
5.2.3.1 Collective Pitch Lock 
To secure the collective pitch lever during ground operation, a 
collective pitch lock is installed. It consists of a spring and a lock latch. 
To lock the collective pitch, the latch is placed onto the locking pinat 
the collective pitch lever head.
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EC135 Classic 
B1 
Training Manual
05 – 11Iss. August 2018For instruction only
Collective Control
05 – Flight Control
5.2.3 Transmission of Control Signals
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EC135 Classic 
B1 
Training Manual
05 – 12Iss. August 2018For instruction only
INTENTIONALLy LEFT BLANK
05 – Flight Control
5.2.3 Transmission of Control Signals
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EC135 Classic 
B1 
Training Manual
05 – 13Iss. August 2018For instruction only
Collective Lever Pilot / Copilot
05 – Flight Control
5.2.3 Transmission of Control Signals
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.4 Weight Compensation
EC135 Classic 
B1 
Training Manual
05 – 14Iss. August 2018For instruction only
5.2.4 Weight Compensation
In order to compensate forces required to move collective levers, a 
weight compensation system is installed. It is adjustable to single and 
dual pilot operation. It is located under the cabin floor attached to the 
collective shaft.
5.2.4.1 Example
To install copilot collective lever:
 – Detach the protective cover on pilot collective lever.
 – Pull the rigging pin from SP (Single Pilot) position and rotate 
the lever approximately 1.8 turns clockwise. 
 – Lock position DP (Dual Pilot) with the rigging pin.
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EC135 Classic 
B1 
Training Manual
05 – 15Iss. August 2018For instruction only
Weight Compensation
05 – Flight Control
5.2.4 Weight Compensation
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.5 Cyclic Control
EC135 Classic 
B1 
Training Manual
05 – 16Iss. August 2018For instruction only
5.2.5 Cyclic Control
5.2.5.1 Signal Input
The cyclic control signals are given by moving the cyclic stick left or 
right (lateral control) and by pushing or pulling it (longitudinal control).
5.2.5.2 Cyclic Stick
The cyclic sticks are located in front of the pilot’s and copilot’s seat. 
Both sticks are linked via the cyclic shaft and a linkage mechanism 
underneath the cabin floor.
5.2.5.3 Control Transmission
Longitudinal control inputs are transmitted via the cyclic shaft to a 
lower horizontal control rod which leads to the lower guidance unit 
beneath the control post. 
Lateral control inputs are transmitted via a linkage which is connected 
above the cyclic shaft to the cyclic stick, to a bell crank and to a lower 
horizontal control rod which leads to the lower guidance unit beneath 
the control post. 
The lower guidance unit transfers longitudinal and lateral control 
inputs as thrust motions to one vertical control rod each. 
The left and the right bell crank of the upper guidance unit transmit the 
thrust motions to one upper horizontal control rod each. One upper 
horizontal control rod displaces the input lever of the longitudinal 
control spool (LH) and the other one displaces the input lever of the 
lateral control spool (RH) at the main rotor actuator. 
The lateral control lever tilts the swashplate forward to the left when 
pushing the cyclic stick to the left and backward to the right when 
pushing the stick to the right. 
5.2.5.4 Vibration Decoupling Unit 
The linkage for decoupling the vibrations is located between the upper 
guidance unit and the main rotor gearbox. This unit supresses control 
inputs induced by vibrations from the main gear box relatively to the 
fuselage. If there is a displacement between themain gearbox and 
the upper guidance unit, the decoupling rod causes a tilting of the 
guidance unit for compensation.
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EC135 Classic 
B1 
Training Manual
05 – 17Iss. August 2018For instruction only
Cyclic Control
05 – Flight Control
5.2.5 Cyclic Control
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.6 Cyclic Centering Device
EC135 Classic 
B1 
Training Manual
05 – 18Iss. August 2018For instruction only
5.2.6 Cyclic Centering Device
A cyclic centering device is installed on the pilots cyclic stick. This 
allows the cyclic stick to be positioned in the center position to reduce 
mast moment forces on the rotor system. It consists of a cantilever 
attached to the cyclic stick and a receptacle pin which is part of the 
instrument panel. This design prevents the cyclic stick from being 
in a locked position which may lead to loss of controllability of the 
helicopter.
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EC135 Classic 
B1 
Training Manual
05 – 19Iss. August 2018For instruction only
Cyclic Centering Device
05 – Flight Control
5.2.6 Cyclic Centering Device
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5.2 Flight Control of the EC135
5.2.7 Mixing Lever Assembly
EC135 Classic 
B1 
Training Manual
05 – 20Iss. August 2018For instruction only
5.2.7 Mixing Lever Assembly
General
The purpose of the mixing lever assembly is to transmit the three 
amplifiedmain rotor control signals (collective, longitudinal and lateral) 
to the swashplate.
5.2.7.1 Main Components
The main components of the mixing lever assembly are:
 – collective control fork
 – two cyclic control levers.
5.2.7.2 Collective Control Fork
The collective fork is supported by the hinged supportmounted on 
top of themain transmission. At the forked end it is connected to the 
sliding sleeve.
5.2.7.3 Cyclic Control Levers
The two cyclic control levers are mounted one on each side of the 
collective control fork. As seen in flight direction, the lateral control 
lever is mounted to the RH side and the longitudinal control lever is 
mounted to the LH side of the collective fork.
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EC135 Classic 
B1 
Training Manual
05 – 21Iss. August 2018For instruction only
Mixing Lever Assembly up to P2+, T2+
05 – Flight Control
5.2.7 Mixing Lever Assembly
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.8 Mixing Lever Assembly P3/T3 Version
EC135 Classic 
B1 
Training Manual
05 – 22Iss. August 2018For instruction only
5.2.8 Mixing Lever Assembly P3 / T3 Version
General
The purpose, function and location of the mixing assembly is identical 
to the former version
5.2.8.1 Main Changes
The main changes are:
 – collective control range
 – mixing Lever Assembly ratios 
 – re-inforcement of mixing lever assembly
 – rotating control rod basic length
 – boosted section adjustment tool
5.2.8.2 Collective Control
The higher control loads on the collective actuator require a reduction 
of collective control range to 0° – 16.3°.
5.2.8.3 Cyclic Control
To maintain the cyclic control range, a change of lever ratios in the 
mixing lever assembly.
5.2.8.4 Mixing Lever Assembly
To ensure staticand dynamic strength, a reinforcement of critcal 
points is done.
♦ NOTE There is no change of interfaces and bolts.
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EC135 Classic 
B1 
Training Manual
05 – 23Iss. August 2018For instruction only
Mixing Lever Assembly P3 / T3 Version
05 – Flight Control
5.2.8 Mixing Lever Assembly P3/T3 Version
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.9 Rotating Control Rods P3/T3 Version
EC135 Classic 
B1 
Training Manual
05 – 24Iss. August 2018For instruction only
5.2.9 Rotating Control Rods P3 / T3 Version
General
The purpose, components and configuration of the rotating control rod 
is indentical to former version. 
Also all notes and warnings are applicable for the rotating control rods.
5.2.9.1 Main Changes 
The only change regarding the rotating control rods is the reduction of 
the basic setup length from 308.8 mm to 307.3 mm.
5.2.10 Adjustment Boosted Section P3 / T3 Version
General
The adjustment procedure for the flight control boosted section is 
similar to the former version.
5.2.10.1 Main Changes
For the adjustment P3 / T3 specific locating rods are required.
♦ NOTE Follow always the current AMM procedure according 
helicopter version. If wrong tooling is used, the 
blade angle range is changed. This could lead to 
control loss over the helicopter.
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EC135 Classic 
B1 
Training Manual
05 – 25Iss. August 2018For instruction only
05 – Flight Control
5.2.10 Adjustment Boosted Section P3/T3 Version
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.11 Principle of the Transmission of Control Signals
EC135 Classic 
B1 
Training Manual
05 – 26Iss. August 2018For instruction only
5.2.11 Principle of the Transmission of Control 
Signals
5.2.11.1 Collective
For increasing the vertical lift of the helicopter the swash plate has to 
be raised evenly by the collective fork and the sliding sleeve (point 1 
to point 1’). 
Thus the pivot points of the lateral and longitudinal levers have to be 
raised as well in order to avoid a cyclic input to the swash plate (point 
2 to point 2’ and point 3 to point 3’).
5.2.11.2 Longitudinal Input (Example Forward Flight):
The longitudinal lever raises point 3 to point 3’ and thereby tilts the 
swash plate. Thus the rotating pitch links, which are mounted at the 
leading edge of the rotor blades, provide the maximum input approx. 
90° prior the tail position of the blades. Due to the gyroscopic effect, 
inertial blade mass and rotor characteristics the blades deliver the 
highest lift at the tail position. The lowest lift is evident at the nose 
position. The rotor plane tilts forward which causes the helicopter to 
fly forward. 
For a rearward flight the swash plate has to be tilted in the opposite 
direction (lowering of point 3) and the rotor plane will tilt to the rear 
according the principle described above.
5.2.11.3 Lateral Input:
The lateral input for left and right follow the same principle as the 
longitudinal control. Point 2 has to be raised or lowered and the 
helicopter will turn left or right.
♦ NOTE Transmission of cyclic signals is totally independant 
of collective control inputs. Collective control 
signals are transferred to both, the sliding sleeve 
and the two short control rods.
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EC135 Classic 
B1 
Training Manual
05 – 27Iss. August 2018For instruction only
Transmission of Cyclic and Collective Signals
05 – Flight Control
5.2.11 Principle of the Transmission of Control Signals
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.12 Swash Plate
EC135 Classic 
B1 
Training Manual
05 – 28Iss. August 2018For instruction only
5.2.12 Swash Plate
General
The swash plate transfers the cyclic or collective control input from the 
stationary part of the flight controls to the rotating blades. 
5.2.12.1 Sliding Sleeve 
The collective control inputsmove the sliding sleeve up or down. 
Inside the sleeve two teflon bushings are attached, which permit easy 
sliding movement on the gearbox mounted support tube. Two bearing 
bolts at the top of the sliding sleeve retain the cardan ring. Two ball 
bearings at the lower side of the sliding sleeve connect the collective 
control fork of the mixing lever unit. 
5.2.12.2 Cardan Ring 
The cardan ring contains four bearings, two for pivoting the cardan 
ring and two for pivoting the control ring. This arrangement constitutes 
a gimbal mounting which enables the interconnected control ring to tilt 
in all directions about the vertical axis. 
5.2.12.3 Control Ring 
The stationary control ring transmits the cyclic inputs via the swash 
plate bearing to the rotating bearing ring. It is connected to the mixing 
lever assembly by two control rods. 
Also at the control ring provision is made for installation of a speed 
pickup for track and balance purposes of the main rotor blades.
5.2.12.4 Swash Plate Bearing 
The swash plate bearing is a duplex ball bearing which connects the 
nonrotating control ring to the rotating bearing ring.
♦ NOTE The swash plate bearing is the only rotating part of 
the helicopter that is lubricated by grease.
5.2.12.5 Bearing Ring 
The bearing ring is rotated synchronously with the rotor through the 
two scissors assemblies. The four forked lugs provide the attachement 
points for the rotating control rods. The connecting bolts from the two 
levers integral with the bearing ring provide the attachment points for 
the scissors assemblies. Located within the bearing ring is a soft-iron 
pin which provides the impulses for a magnetic pick-up for track and 
balance purposes.
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EC135 Classic 
B1 
Training Manual
05 – 29Iss. August 2018For instruction only
Swash Plate Assembly
05 – Flight Control
5.2.12 Swash Plate
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.13 Rotating Control Rod
EC135 Classic 
B1 
Training Manual
05 – 30Iss. August 2018For instruction only
5.2.13 Rotating Control Rod
General
The purpose of the rotating control rods is to transmit the flight control 
signals to themain rotor blades. Four rotating control rods are installed 
between the rotating part of the swash plate and the pitch horns at the 
rotor blades.
5.2.13.1 Components
Each rotating control rod consists of:
 – two bearing rod ends
 – two counter nuts
 – two keyed washers
 – rod body.
5.2.13.2 Configuration
The bearing rod ends are screwed into the rod body by a coarse thread 
(MJ10x1.25) on one side and a fine thread (MJ10x1.00) on the other 
side. The rod ends are secured in the rod body by a keyed washer 
and a counter nut on each side. The counter nuts are additionally 
lockwired. To prevent corrosion inside the rod body, the upper end is 
sealed by a sealing compound.
♦ NOTE The coarse thread must be located on the top. If not, 
the adjustment for the blade track by rotating the 
rod body is not as described in the maintenance 
manual.
♦ NOTE The metric threads of some high loaded bolted 
connections might be designed according the MJ 
standard.Due to modifications in the thread root 
area an improved stability is achieved. In addition, 
the self locking behaviour has been improved due 
the selected relationship of thread diameter and 
pitch. For combinations or exchangeability of MJ 
and standard ISO M threads the remarks in the IPC 
have strictly to be followed. For identification the 
letters “MJ” are imprinted on bolts/nuts.
♦ WARNING The threads of the rod ends are marked by red 
paint. These red areas must not be visible after 
adjustment / installation.
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EC135 Classic 
B1 
Training Manual
05 – 31Iss. August 2018For instruction only
Rotating Control Rod
05 – Flight Control
5.2.13 Rotating Control Rod
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.14 Scissors Assembly
EC135 Classic 
B1 
Training Manual
05 – 32Iss. August 2018For instruction only
5.2.14 Scissors Assembly
General
The scissors assembly connects the swash plate to the rotor mast. Its 
purpose is to drive the rotating part of the swash plate. The driving unit 
connects the bearing ring of the swash plate with the scissors clamp 
at the main rotor mast.
5.2.14.1 Attachment
The scissors assembly is connected to the main rotor mast by two 
integrated lugs. Each of the two scissors assemblies are connected 
to the swash plate by means of a spherical bearing and a swash plate 
installed bolt.
♦ NOTE The lettering OUTER SIDE on the lever faces 
outboard.
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EC135 Classic 
B1 
Training Manual
05 – 33Iss. August 2018For instruction only
Scissors Assembly
05 – Flight Control
5.2.14 Scissors Assembly
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.15 Trim System
EC135 Classic 
B1 
Training Manual
05 – 34Iss. August 2018For instruction only
5.2.15 Trim System
General
As the EC135 is equipped with hydraulic boost units for main rotor 
control, which amplify the control signals, no real control forces are 
necessary at the control stick.
For better handling of the helicopter, an artificial control force giving 
the pilot a reference for stick displacement is desireable. For that 
reason, trim actuators with artificial force feel springs are installed in 
the non–boosted section of the cyclic controls. 
During flight, the pilot does not onlymove the stick for a short time, e.g. 
flying a turn, but also for a long time, e.g. during cruise. Holding the 
cyclic stick against the artificial control force would fatique the pilot. 
Therefore the artificial control force can be trimmed to zero in each 
stick position by electric motors and clutches in the trim actuators.
5.2.15.1 Trim Actuators
The longitudinal trim actuator is installed beneath the cabin floor 
centered directly behind frame 1 and in front of the cyclic shaft. The 
lateral trim actuator is installed beneath the cabin floor centered 
behind the cyclic shaft and in front of frame 2. 
In the housing of an actuator there are mounted a DC motor, an 
electro–mechanical clutch, a centrifugal friction brake, a position 
sensor and a spring for artificial force feel. 
5.2.15.2 Trim Linkage 
The longitudinal trim rod connects the output lever of the longitudinal 
trim actuator with the cyclic shaft. 
The lateral trimrod connects the output lever of the lateral trimactuator 
with a bell crank mounted on top of the cyclic shaft. 
5.2.15.3 Control Board 
The control board for the trim system is installed beneath the cabin 
floor between the cross beam and Frame 2. The Unit is attached to 
the floorboard. On the control board there are mounted two relays for 
control of the DC motors. 
5.2.15.4 4–Way Trim Switches 
The 4–way trimswitches are installed on top of both cyclic control stick 
grips, respectively. 
The desired trim position of the cyclic control is adjusted by the 4–way 
trim switches. 
5.2.15.5 Push Buttons 
The push buttons ATT TRIM REL to release the trim position are 
installed on top of both cyclic stick grips, respectively. 
5.2.15.6 Dual Controls 
If dual controls are installed, the 4–way trim switch priority is set to trim 
aft / right, regardless whether the trim signal is triggered by the pilot 
or the copilot. 
5.2.15.7 Circuit Breaker 
The circuit breakers TRIM ACT and TRIM REL are mounted in the 
overhead console.
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EC135 Classic 
B1 
Training Manual
05 – 35Iss. August 2018For instruction only
Trim System - Locations
05 – Flight Control
5.2.15 Trim System
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05 – Flight Control
5.2 Flight Control of the EC135
5.2.15 Trim System
EC135 Classic 
B1 
Training Manual
05 – 36Iss. August 2018For instruction only
5.2.15.8 Function
The function of the longitudinal and lateral trim actuator is identical.
By operating the 4–way trim switch at the cyclic stick, the DC motor in 
the trim actuator drives the primary reducer (wormgear) and transmits 
the movement to the closed electrical clutch. With the clutch the 
primary reducer is connected to the secondary reducer and the motor 
movement is transmitted to the output shaft. Via the output lever and 
a control rod, the stick is moved into a new force free neutral position.
The running direction of a trim motor is changed by a polarity reversal. 
The on–board circuitry with the relais and the two DC motors enables 
the cyclic stick in four directions: Forward, aft, left, right. 
When operating the 4–way trim switch only one of the four contacts 
can be closed.When releasing the switch, all four contacts are opened 
again. 
During a cyclic control input the trim actuator output lever moves 
together with the cyclic controls. With the trim actuator deenergized, 
no movement of the reduction geartrain is possible. By the relative 
movement between the two gears, the spring becomes twisted, thus 
creating an artificial control force. 
Depressing the ATT TRIM REL push button at the cyclic stick 
energizes the electric clutch in the trimactuator. The clutch opens 
and separates the secondary reducer fromthe primary reducer. This 
allows the secondary reducer to turn and the spring to move in the 
force free position. To smooth this movement the centrifugal friction 
brake generates torque resistance proportional to speed. 
After releasing the ATT TRIM REL push button, a new force free stick 
position is maintained.
♦ NOTE In case of accidental jamming of any internal trim 
actuator parts, a higher control force has to be 
applied to break a shear pin in the affected trim 
actuator output shaft. This allows free movement in 
the respective direction without an artificial control 
force. In that case the trim system in the associated 
direction is disabled, too.
♦ NOTE If the helicopter is equipped with an autopilot system, 
there are a hands–on–detection potentiometer and 
a position transmitter (RVDT) integrated in the trim 
actuators. The P/Ns of the trim actuators are different 
acc. to the H/C configuration (AP vs. Non AP).
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EC135 Classic 
B1 
Training Manual
05 – 37Iss. August 2018For instruction only
Trim System - Trim Actuator
05 – Flight Control
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5.2 Flight Control of the EC135
5.2.15 Trim System
EC135 Classic 
B1 
Training Manual
05 – 38Iss. August 2018For instruction only
5.2.15.9 Dual Controls
If dual controls are installed, the 4-way trim switch priority is set to trim 
aft / right, regardless of whether the trim signal is triggered by the pilot 
or the copilot.
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EC135 Classic 
B1 
Training Manual
05 – 39Iss. August 2018For instruction only
Trim System - Functional Diagram
05 – Flight Control
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05 – Flight Control
5.3 Tail Rotor Control
5.3.1 Components 
EC135 Classic 
B1 
Training Manual
05 – 40Iss. August 2018For instruction only
5.3 Tail Rotor Control
General
The tail rotor control changes the angle of incidence of the tail rotor 
blades collectively. The tail rotor control is used for the yaw control. 
Control inputs aremade by the pilot via the pedal assembly. The pedal 
inputs are superimposed by inputs from the Yaw Stability Augmentation 
System (YAW-SAS) via an electro-mechanical actuator. The inputs 
are boosted hydraulically and transmitted to the control spider which 
changes the blade angles. 
5.3.1 Components 
The tail rotor controls consist of the following assemblies:
 – pedal assembly
 – Flexball control cable
 – yaw-SAS actuator 
 – Fenestron® actuator (booster).
5.3.1.1 Pedal Assembly
The pedal assembly consists of:
 – 2 pedals
 – 2 pedal control rods
 – bellcrank lever.
The pedal assemblys of the pilot and copilot are linked by a connection 
rod. 
5.3.1.2 yaw Actuator
The yaw actuator is an actuator with an integral position feedback 
(Smart electro-mechanical actuator, SEMA). It converts the stabilizing 
signal produced by the fibre optic gyro (FOG) into a corresponding 
mechanical input to the tail rotor control linkage. 
The series-connected yaw actuator operates between the Flexball 
control cable and the hydraulic tail rotor actuator. In consequence, 
stabilizing inputs from the yaw stability augmentation system and the 
control inputs from the pilot are superimposed on each other.
Following a stabilizing input, the yaw actuator automatically recenters 
within its maximum stabilizing stroke range to ensure full stabilizing 
input authority. The authority in the yaw actuator control is 9.25 %.
5.3.1.3 Flexball Control Cable 
The Flexball control cable consists of a double-row arrangement of 
steel balls leading through captive ball cages. The steel balls roll 
between two outer races and a center core. A flexible casing encloses 
the races. Due to this construction the center core is able to transmit 
identical tensile and compression forces.
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EC135 Classic 
B1 
Training Manual
05 – 41Iss. August 2018For instruction only
Tail Rotor Control
05 – Flight Control
5.3 Tail Rotor Control
5.3.1 Components 
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05 – Flight Control
5.3 Tail Rotor Control
5.3.2 Function of the Tail Rotor Control
EC135 Classic 
B1 
Training Manual
05 – 42Iss. August 2018For instruction only
5.3.2 Function of the Tail Rotor Control
The angle of incidence of the tail rotor blades can be varied within a 
range of -16.8° thru +34.2° for up to P2+ / T2+; +35.3° from P3 / T3. 
If e.g. a control input “yaw to the left” ismade by actuating the left pedal 
of the pedal assembly, this input is transmitted as a tension motion via 
control rods and the guidance unit to the Flexball control cable. 
The Flexball control cable actuates a control rod in the Fenestron® 
and thus the input of the yaw actuator. The yaw actuator superimposes 
additional control inputs of the yaw stability augmentation system. The 
part of the control rod located behind the yaw control actuator pulls the 
input lever. 
The Fenestron® actuator increases the force at the input lever and 
axially shifts the rotating control spider via its piston rod to the right. 
The levers of the control spider convert the axialmotion into a positive 
twist of the rotor blades.
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EC135 Classic 
B1 
Training Manual
05 – 43Iss. August 2018For instruction only
Fenestron® Actuator
05 – Flight Control
5.3.2 Function of the Tail Rotor Control
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05 – Flight Control
5.4 Hydraulic System
5.4.1 Components
EC135 Classic 
B1 
Training Manual
05 – 44Iss. August 2018For instruction only
5.4 Hydraulic System
General
The hydraulic system is used to boost the manual control inputs of the 
pilot. At the same time the reset forces of the rotor blades are blocked.
5.4.1 Components
The hydraulic system consists of the following components:
 – two identical pressure supply systems
 – main rotor actuators
 – Fenestron® actuator
 – indicating and testing system.
Tab. 05-1: Leading Particulars Hydraulic System
Operating pressure 103 bar
Return pressure 1.40 - 1.75 bar
Hydraulic fluid acc. MIL-H 5606 (F)
Fluid capacity 1.0 l (SYS 1), 1.2 l (SYS 2)
Reservoir capacity 0.8 l
♦ NOTE To prevent a contamination and blockage, it is 
recommended that hydraulic fluid stored in cans 
should not be used when it is older than 3 years.
5.4.2 Location
The components of the hydraulic power system are installed at the 
front of the main transmission and in the cockpit. Two pressure supply 
systems are installed on top of the accessory gearboxes. The fan 
gearboxes are attached to the left-hand and right-hand forward side 
of the main transmission. The main rotor actuators are installed in the 
center of the forward side of the main transmission. The Fenestron® 
actuator is installed inside the stator hub of the Fenestron®. Hydraulic 
lines connect the pressure supply systems to the main rotor actuators 
and the Fenestron® actuator. The components of the indicating and 
testing system are part of the pressure supply systems. The related 
switches and displays are installed in the overhead panel and in the 
instrument panel.
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EC135 Classic 
B1 
Training Manual
05 – 45Iss. August 2018For instruction only
Pressure Supply System
05 – Flight Control
5.4 Hydraulic System
5.4.2 Location
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05 – Flight Control
5.4 Hydraulic System
5.4.3 Redundancy Provision
EC135 Classic 
B1 
Training Manual
05 – 46Iss. August 2018For instruction only
5.4.3 Redundancy Provision
The hydraulic power system is a dual system. It has two identical 
pressure supply systems, system 1 and system 2, that operate 
independently. Under normal operating conditions both pressure 
supply systems simultaneously generate the entire pressure for 
boosting the main rotor controls. System 2 in addition also boosts 
the tail rotor controls. If one of the pressure supply systems fails, the 
remaining system continues to supply the main rotor actuators. This 
causes the operating force of the mechano-hydraulically operated 
main rotor actuators to decrease to half.
Only the failure of system 2 causes the tail rotor control to operate 
without pressure. Failure of system 1 has no effect on the Fenestron® 
actuator.
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B1 
Training Manual
05 – 47Iss. August 2018For instruction only
Hydraulic System - Schematic
05 – Flight Control
5.4.3 Redundancy Provision
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05 – Flight Control
5.5 Indication and Testing Systems
5.4.3 Redundancy Provision
EC135 Classic 
B1 
Training Manual
05 – 48Iss. August 2018For instruction only
5.5 Indication and Testing Systems
General
Each system has a pressure switch to monitor the operating pressure. 
Power is supplied through the ESS busbar and the related circuit 
breakers. 
With system pressure above approx. 83 bar, the pressure switch is 
open and the caution HYD PRESS disappears. 
System pressure of less than approx. 69 bar closes the pressure 
switch. The caution indication HYD PRESS is displayed on display 
segment SYSTEM I or SYSTEM II on CDS / CPDS.
Components
The components of the indicating and testing system are:
 – pressure switch for System 1 / 2 
 – solenoid valve for System 1 / 2
 – shut-off valve for System 1 / 2
 – circuit breaker HyD-P SyS 1 / 2
 – relay for System 1 / 2 
 – display system CDS / CPDS 
 – test switch (spring loaded).
Test Procedure
As both hydraulic systems operate simultaneously one system has 
to be switched off to test the other. Testing System 2 (test switch 
in position SYS 2) system 1 is switched off (and vice versa) via the 
solenoid valve. The pressure in System 1 drops and the pressure 
switch activates the CDS / CPDS caution HYD PRESS in system 1. 
With small control inputs on ground the pilot can test the enforcement 
of the respective system.
♦ NOTE Testing System 1 the pedal forces will increase 
because System 2 and therefore the Fenestron® 
actuator is switched off.
♦ WARNING The test has to be performed on ground only.
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EC135 Classic 
B1 
Training Manual
05 – 49Iss. August 2018For instruction only
Hydraulic System - Indication and Testing System
05 – Flight Control
5.5 Indication and Testing Systems
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05 – Flight Control
5.5 Indication and Testing Systems
5.5.1 Pressure Supply Systems
EC135 Classic 
B1 
Training Manual
05 – 50Iss. August 2018For instruction only
5.5.1 Pressure Supply Systems
General
The pressure supply systems 1 and 2 are two identical systems. They 
independently supply the hydraulic actuators with operating pressure.
Components
Each pressure supply system consists of:
 – hydraulic pump
 – reservoir
 – valve block
 – hydraulic lines.
♦ NOTE To prevent the hydraulic systems from contamination 
an external ground cart must not be connected. 
System tests can be carried out by operating the 
hydraulic pumps with a special tool. To refill the 
systems a container with a hand--pump and a fine 
filter are available.
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EC135 Classic 
B1 
Training Manual
05 – 51Iss. August 2018For instruction only
Pressure Supply System
05 – Flight Control
5.5.1 Pressure Supply Systems
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05 – Flight Control
5.5 Indication and Testing Systems
5.5.1 Pressure Supply Systems
EC135 Classic 
B1 
Training Manual
05 – 52Iss. August 2018For instruction only
5.5.1.1 Hydraulic Pump
The hydraulic pump is an integral part of the pressure system. All 
connections (i.e. pressure line, suction line, case drain) are made by 
channels and bores in the valve block. 
The pump is conventional piston type wherein a cylinder barrel 
containing nine pistons is driven by the accessory drive of the main 
transmission. 
The pistons are constrained by the rotating part of the backplate and 
ball-and-socket-joints shoes which are hydrostatically balanced. As 
the barrel rotates, the pistons intake and discharge fluid through a 
stationary valve surface (control plate) on the port cap. The length 
of the piston stroke, and thereby the displaced volume is determined 
by the angle of the non-rotating part of the backplate. This angle is 
controlled by a spring acting against system pressure on the cam of 
the non-rotating part.
♦ NOTE The longer the stroke of the pistons, the larger the 
volume of fluid delivered.
Tab. 05-2: Leading Particulars Hydraulic Pump
Speed 5145 RPM
Preloaded pressure in thee
reservoir
1.40–1.75 bar
Reservoir capacity 0.8 l
Low pressure relief valve Opens at 6.5 bar
High pressure relief valve Opens at 122 bar
Pressure switch 
(increasing pressure)
Opens at 82.7 bar
Pressure switch 
(decreasing pressure)
Closes at 69 +/- 3.4 bar
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EC135 Classic 
B1 
Training Manual
05 – 53Iss. August 2018For instruction only
Hydraulic Pump Operation
05 – Flight Control
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5.5 Indication and Testing Systems
5.5.2 Reservoir
EC135 Classic 
B1 
Training Manual
05 – 54Iss. August 2018For instruction only
5.5.2 Reservoir
The reservoir stores the hydraulic fluid. The necessary preload 
pressure is generated by the double actuated piston in the reservoir. 
The operating pressure applies a force on the smaller piston. As 
a result the larger piston pressurizes the reservoir. With the ratio 
between the both piston areas (1:60) and an operating pressure of 
103 bar, a return pressure of 1.40 – 1.75 bar is created in the reservoir 
to prepressurize the pump suction side. 
A pressure relief valve avoids a damage of the reservoir caused 
by overpressure. It opens at a pressure of 6.5 bar and relieves out 
hydraulic fluid to the leak oil port. 
Both the reservoirswith the valve blocks attached to their forward side, 
are installed on the hydraulic pumps. A support bracket also attaches 
them to the main transmission. 
The sight glass on the top of the reservoir serves as an indicator for 
the amount of air in the system. 
A fluid level indicator is installed on the rear side of the reservoir.
♦ NOTE The sight glass must be half full of hydraulic fluid 
minimum. Otherwise the system has to be bled. A 
save flight operation is assured as long as fluid is 
visible in the sight glass.
Valve Block 
The valve block contains all the valves and control lines to control and 
test the hydraulic system. 
Directly after the hydraulic pump there is a non return valve to prevent 
a reversal of the fluid’s direction of flow. 
The filter prevents the system from contamination. 
The pressure relief valve prevents overloading of the system. The 
valve opens at a pressure of 122 bar and excessive pressure is 
released to the return side. 
The solenoid valve, the shut off valve and the pressure switch are part 
of the indication and test system.Energizing the solenoid valve causes 
the shut off valve to close. The resulting decrease in pressure causes 
the pressure switch to close and to send a signal to the cockpit for low 
pressure caution indication. 
Maintenance 
For maintenance purpose the following ports are available: 
 – bleed valve and sightglass for detection and bleeding of 
trapped air (in system 2 a second bleed valve is mounted at 
the Fenestron® actuator)
 – maintenance port for pressure monitoring (high pressure 
side).
 – refill and bleed port for draining and refilling the system (low 
pressure side).
♦ NOTE Due to internal piping the refill port is mounted at 
the plate assy in reverse order.
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B1 
Training Manual
05 – 55Iss. August 2018For instruction only
Reservoir / Valve Block - Cross Section
05 – Flight Control
5.5.2 Reservoir
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5.5 Indication and Testing Systems
5.5.3 Hydraulic Valve Block - Normal Operation
EC135 Classic 
B1 
Training Manual
05 – 56Iss. August 2018For instruction only
5.5.3 Hydraulic Valve Block - Normal Operation
The hydraulic pump delivers a constant pressure of 103 bar via the 
non return valve and the filter to following locations:
Location 1 Small piston chamber (left section) of the reservoir piston 
unit. 
Result: The force at the piston rod due to the high pressure in the 
small chamber creates the low pressure in the large piston chamber 
(right section) with a relationship of 60:1. 
Location 2 Right side of the shut off valve. 
Result: The force generated by the high pressure piston (right side) 
and the spring force override the force created by the low pressure 
piston and keep the shut off valve in the opened position. 
Location 3 Center section of the shut off valve.
Result: As the shut off valve is being kept in the open position the 
high pressure outlet is pressurized. The pressure switch is open and 
therefore the caution HYD PRESS in the CDS/CPDS is suppressed. 
In this situation the respective main rotor actuator system is supplied 
with high pressure. The returning fluid from the actuators is recycled 
by the hydraulic pump or led to the reservoir, depending on the flow 
demand. 
Location 4 Solenoid Valve inlet. 
Result: In this situation none.
Hydraulic Valve Block - Test Function activated
For the single system test on ground one system has to be shut off 
with the spring loaded test switch in the overhead panel. During the 
test the solenoid valve is activated and opens the high pressure inlet 
for the left side of the shut off valve. 
Result: the piston of the shut off valve travels to the right end stop 
because the force created by the larger piston surface and the high 
pressure is greater than the force created by the spring and the smaller 
piston surface with high pressure applied. 
The pressure outlet is blocked and the pressure switch closes (Caution 
HYD PRESS in the CDS / CPDS for the respective system comes on). 
The pressure outlet line and the main rotor actuator of the deactivated 
system are connected to the return pressure as long as the test 
situation is evident.
Hydraulic Valve Block - Test Function deactivated 
The test switch is released to the norm position, the solenoid valve 
closes the high pressure inlet for the left shut off valve piston and the 
shut off valve reverts to the open position again. The fluid of the left 
piston chamber is pushed into the low pressure line which is opened 
simultaneously. 
Result: The pressure switch opens again (caution HYD PRESS goes 
off) and themain rotor actuators are supplied with high pressure again.
♦ NOTE Both hydraulic systems can be tested with this 
procedure. Only when testing system 1 (system 
2 is inactive) there is no pressure supply to the 
Fenestron® actuator. 
♦ WARNING Never activate the hydraulic test switch in flight.
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EC135 Classic 
B1 
Training Manual
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Reservoir / Valve Block - Cross Section
05 – Flight Control
5.5.3 Hydraulic Valve Block - Normal Operation
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05 – Flight Control
5.6 Hydraulic Actuators
5.6.1 Assembly
EC135 Classic 
B1 
Training Manual
05 – 58Iss. August 2018For instruction only
5.6 Hydraulic Actuators
General
Due to the high reset forces which react on the controls when changing 
the blade pitch, hydraulic actuators transmit boosted control inputs to 
the rotor system. 
The main rotor actuator block consists of three adjacent hydraulic 
actuators. It is installed at the front part of the main rotor gearbox by 
means of an attachment and supply plate.
5.6.1 Assembly
The hydraulic actuator mainly consists of:
 – servo valve 
 – boost cylinder
5.6.2 Description of the Follow-up Principle
5.6.2.1 Fluid Flow
System pressure is supplied from the pump via the valve block to 
the control spool. Depending on the control spool position the upper 
or lower side of the piston is pressurized. The boost piston moves 
in the corresponding direction. The low pressure fluid from the non 
pressurized chamber is led back through the return line into the 
reservoir. 
With the control spool in the neutral position, no boost piston movement 
is possible, because the pressure line aswell as both return lines are 
closed. The boost piston is hydraulically blocked.
5.6.2.2 Control Input 
The input control rod is moved upward. At themoment of the input, 
the boost piston cannot move, because it is still hydraulically blocked. 
Therefore, when the control input rod moves upward, the control lever 
turns around the pivot point at the boost piston. The control spool in 
the control valve is pulled down by means of the connecting rod and 
the control lever. This opens the upper port of the servo valve, directing 
hydraulic pressure into the upper chamber of the boost cylinder. In the 
same moment the return line of the lower chamber opens and the fluid 
moves back to the reservoir.
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Training Manual
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Hydraulic Actuator - Basic System Function
05 – Flight Control
5.6 Hydraulic Actuators
5.6.2 Description of the Follow-up Principle
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05 – Flight Control
5.6 Hydraulic Actuators
5.6.1 Assembly
EC135 Classic 
B1 
Training Manual
05 – 60Iss. August 2018For instruction only
5.6.2.3 Reaction of the Boost Piston
The hydraulic pressure in the upper chamber of the boost cylinder 
causes the piston to move down. Low pressure fluid from the lower 
boost cylinder chamber is ported to the servo valve and to the reservoir 
via the return line. With the boost piston moving down and a constant 
movement at the input control rod upward, themiddle point of the 
control lever becomes the pivot point where the control lever turns 
around. The control spool remains pulled down as long as the input 
continues.
5.6.2.4 Input Stop 
When there is an input stop, the upper spherical bearing of the control 
lever becomes the pivot point. As the control spool is still in the open 
position, the boost piston moves until the control spool is pushed back 
in the closed position by the connecting rod and the control lever.
With the control spool in the neutral position no further hydraulic flow 
is possible and the boost piston becomes hydraulically blocked again. 
This short time delay is not perceptible in the controls.
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Training Manual
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Hydraulic Actuator - Basic System Function
05 – Flight Control
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05 – Flight Control
5.7 Mechano-Hydraulic Actuator MHA
5.7.1 Assembly
EC135 Classic 
B1 
Training Manual
05 – 62Iss. August 2018For instruction only
5.7 Mechano-Hydraulic Actuator MHA
5.7.1 Assembly
The mechano-hydraulicactuator MHA (collective axis) consists of 
two independent systems which are mounted as a unit. Both systems 
have one common piston rod and are located opposite each other. 
System 1 with the respective mounting and supply plate is located on 
the top at the power piston output, system 2 with the respective supply 
plate is located below.
5.7.2 Function
The control linkage for collective control is connected to the input lever 
of the main rotor actuator. The piston rod of the main rotor actuator is 
connected to the mixing lever gear unit by means of control links. 
Without hydraulic pressure the system is switched off by the combined 
shut–off valve and bypass valve unit. Two springs with different spring 
rates keep the valves in the desired position. 
With the operating pressure increasing via the pressure port and the 
check valve the inlet chamber of the shut–off valve is pressurized. Via 
the hollow piston shaft and the orifice the control chamber pressure 
increases more slowly and causes at first the bypass valve to close 
with the compression of the weak spring. After the bypass contacts 
the conical seating the strong spring will be compressed and the two 
piston sections move relative to each other and open the shut-off 
valve. Thus the pressure is led through to the control spool. In this 
situation the boost piston is hydraulically blocked and counteracts all 
forces coming back from the rotor. 
A control input made at the input lever moves the control spool out 
of the neutral position and the operating pressure is directed to the 
respective boost piston chamber. The boost piston moves as long the 
input continues and the control spool remains in the open position. 
The opposite piston chamber is opened to the return line in order to 
allow the piston travel. 
When the input stops the boost piston pulls the control spool back 
into the neutral position via the connection rod and the boost piston 
movement stops (follow up principle). 
The boost piston is hydraulically blocked in the new position. 
The mechanical end stop for the boost piston travel is in the piston 
chamber and will be reached, if the control input is continued. 
In case of operating pressure drop (normal run down; system switched 
off for test purpose; broken hydraulic line; control line with operating 
pressure released to the return pressure) as a consequence the 
pressure in the control chamber drops and the strong spring closes 
first the shut--off valve, then the weak spring opens the by pass valve. 
The system is depressurized and the boost piston chambers are 
interconnected in the concerned system. 
If the second system is still operative the boost piston in the deactivated 
system does not block the control movement.
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EC135 Classic 
B1 
Training Manual
05 – 63Iss. August 2018For instruction only
Mechano-Hydraulic Actuator MHA
05 – Flight Control
5.7 Mechano-Hydraulic Actuator MHA
5.7.2 Function
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5.7 Mechano-Hydraulic Actuator MHA
5.7.3 Mechanical Override
EC135 Classic 
B1 
Training Manual
05 – 64Iss. August 2018For instruction only
5.7.3 Mechanical Override
5.7.3.1 Purpose
Because the control spools of the two systems are mechanically linked 
to each other, a jammed control spool in one system would cause 
blocking of the corresponding control spool within the other system. 
In order to assure the function of the hydraulic system in case one 
control spool jams, a mechanical override is installed to each system.
5.7.3.2 Assembly 
The control spool is moving in a valve sleeve, which is kept in position 
by two springs. A test button is installed to the springs housing.
5.7.3.3 Function 
In case of a jammed control spool, every control input will shift the 
control spool and the control spool sleeve together against the spring 
forces. The first displacement of the control spool sleeve causes the 
opening of the control line to return pressure, thus first the shut–off 
valve closes and then the bypass valve opens. A bypass around the 
boost piston chambers of the respective system is established.
♦ NOTE In case of a jammed control spool an increased 
control force in the affected axis will be observed.
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EC135 Classic 
B1 
Training Manual
05 – 65Iss. August 2018For instruction only
Mechanical Override
05 – Flight Control
5.7.3 Mechanical Override
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5.7 Mechano-Hydraulic Actuator MHA
5.7.4 System Test
EC135 Classic 
B1 
Training Manual
05 – 66Iss. August 2018For instruction only
5.7.4 System Test
A test button, installed to each spring housing allows checking the 
valve sleeve for free movement. Pressing the test button will first close 
the gap between button and sleeve. Then, increase of applied force 
will cause the displacement of the control spool sleeve. Caused by the 
spring forces, the test button returns back to its normal position after 
the return pressure has been built up.
♦ NOTE If, after closing the gap, no further movement is 
possible against the spring force, the valve sleeve 
may be blocked in the housing or the control spool 
may be jammed in the control spool sleeve.
♦ NOTE Due to the friction between the test button and the 
seal, the test button will be pressed out fully by the 
return pressure only.
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EC135 Classic 
B1 
Training Manual
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Override test
05 – Flight Control
5.7.4 System Test
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05 – Flight Control
5.8 Electro-Hydraulic Actuator EHA
5.8.1 Function
EC135 Classic 
B1 
Training Manual
05 – 68Iss. August 2018For instruction only
5.8 Electro-Hydraulic Actuator EHA
General
For the longitudinal and lateral axis (pitch and roll) an electro–hydraulic 
actuator (EHA) together with a MHA compose the complete actuator. 
The electrical control signal sent from SAS and / or A/P to the EHA 
will be converted into a mechanical control input by hydraulics. This 
enables superimposition of this input with the mechanical input coming 
from the control rods (pilot, trim system, SEMA).
5.8.1 Function
The basic functions concerning boost piston and control spool are 
similar to the mechano–hydraulic actuator as described for the 
collective axis. 
In order to allow the control piston inputs to the control spool and 
thereby to the control output the mechanical linkage is modified. As 
long as the SAS is inactive the control piston is centered by two springs 
and the control spool moves only after an input coming from the pilot. 
When the supply line from P1 to the solenoid valve is pressurized 
the control pressure builts up via the solenoid valve and closes the 
bypass valve. 
Thus the operating pressure can be directed into one of the control 
piston chambers by the piston unit in the solenoid valve. The position 
of the piston unit is controlled by the SAS computer via electromagnetic 
signals to the servo valve coils. The position sensor signal is used as 
a feedback signal for the control loop in the SAS computer. 
With both control piston chambers interconnected no differential 
pressure builds up and no influence from the SAS is possible.
5.8.1.1 EHA - SAS Decoupled
The complete SAS (P&R and YAW SAS) can be switched off by the 
pilot manually. Inthis case the solenoid valve is activated directly by 
the cutoff switch on the cyclic stick. 
The control pressure will be relieved to the return line and the spring 
force will open the bypass valve. Then the control piston will be centered 
independent from its present position. The orifice in the bypass valve 
causes a delay in order to avoid a control input. Therafter the control 
spool and the boost piston move only after a mechanical input via the 
flight controls.
♦ NOTE In case of hydraulic system 1 failure the P&R SAS 
will be inoperative.
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EC135 Classic 
B1 
Training Manual
05 – 69Iss. August 2018For instruction only
Electro - Hydraulic Actuator EHA
05 – Flight Control
5.8 Electro-Hydraulic Actuator EHA
5.8.1 Function
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05 – Flight Control
5.9 Fenestron® Actuator
5.9.1 Function 
EC135 Classic 
B1 
Training Manual
05 – 70Iss. August 2018For instruction only
5.9 Fenestron® Actuator
General
The Fenestron® actuator is used for boosting the inputs for the tail 
rotor control. It is bolted to the tail rotor gearbox. It transmits pedal 
inputs to the control spider for changing the angle of incidence of the 
tail rotor blades. Integrated in the Fenestron® actuator are the stops 
for the maximum and minimum control range. The actuator is supplied 
with pressure by the pressure system 2. 
5.9.1 Function 
Without hydraulic pressure the two springs with different spring rate 
keep the bypass valve (weak spring) in the opened and the shut-off 
valve (strong spring) in the closed position. 
Thus the power piston can travel freely and the pilot is able to give 
inputs to the tail rotor by means of the mechanical linkage only. 
When operating pressure fills the shutoff valve inlet chamber and the 
control chamber through the hollow piston rod, the valve unit starts to 
travel to the right. First the by pass closes (weak spring); second the 
shutoff valve opens and gives the pressure free to the control spool 
inlet. 
The input lever is connected with the piston rod of the power piston. 
Via the control lever the control spool can be moved. Pulling the input 
lever displaces the control spool to the right and the operating pressure 
enters the left power piston chamber which causes again amovement 
to the right as long as the input lever continues to travel.
The control spool closes the pressure and return line as soon as the 
required position of the power piston has been reached (input lever 
stops the movement) due to the follow up of the control lever. 
The movement of the power piston is stopped and the power piston is 
kept in its position until a new control input is made. 
If the pressure drops in system 2, the shutoff valve closes and the 
by-pass valve opens. Both boost piston chambers are interconnected 
and the mechanical control can displace the power piston. 
The control spool normally travels in the valve sleevewhich is centered 
by two springs. If the control spool is blocked the valve sleeve can 
be shifted against the spring force. Thus the control line is directly 
connected to the return line. If the pressure drops in the control line, 
the bypass valve switches the system off via the shut-off valve unit as 
described above. The pilot will feel slightly higher control forces in the 
affected axis because one of the springs at the valve sleeve has to be 
compressed. 
The function of the test button is similar to these of the MHA and EHA.
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EC135 Classic 
B1 
Training Manual
05 – 71Iss. August 2018For instruction only
Fenestron® Actuator
05 – Flight Control
5.9 Fenestron® Actuator
5.9.1 Function 
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05 – Flight Control
5.10 Three Axis Stability Augmentation System SAS
5.9.1 Function 
EC135 Classic 
B1 
Training Manual
05 – 72Iss. August 2018For instruction only
5.10 Three Axis Stability Augmentation System SAS
General
The helicopter can be equipped with an optional 3–axis Stability 
Augmentation System (SAS). 
The 3–axis stability augmentation system comprises the following 
independent subsystems: 
 – yaw stability augmentation system (standard equipment)
 – pitch and roll stability augmentation system (option)
 – pitch damper for DPIFR certified H/C (option).
Requirements / Modular Structure
If the helicopter is equipped with an autopilot system (AFCS), the SAS 
becomes part of the autopilot system architecture. 
A precondition for operating of the AFCS is the 3–axis SAS and the 
pitch damping system. Nevertheless, the 3–axis SAS and the pitch 
damping system can be operated as a “stand alone” system without 
the AFCS under VFR and DPIFR rules.
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Training Manual
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VFR / IFR Requirements and AFCS
05 – Flight Control
5.10 Three Axis Stability Augmentation System SAS
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05 – Flight Control
5.10 Three Axis Stability Augmentation System SAS
5.10.1 Yaw Stability Augmentation System
EC135 Classic 
B1 
Training Manual
05 – 74Iss. August 2018For instruction only
5.10.1 yaw Stability Augmentation System
General
The yaw stability augmentation system applies limited authority control 
inputs to the tail rotor control linkage. 
The yaw SAS operates independently of the other flight control 
systems and provides the following functions:
 – enhancement of the dynamic yaw stability
 – damping of gust effects on the yaw axis.
The system is designed for “feet-on” operation, thereby requiring the 
pilot to provide helicopter yaw control by operating the pedals. In turn, 
the pilot experiences improved handling qualities while at the same 
time retaining full control input authority.
System Components
The yaw stability augmentation system consists of the following 
components:
 – fiber optical gyro (FOG) 
 – yaw actuator (SEMA) 
 – circuit breaker yAW SAS 
 – cut-off switch SAS DCPL
 – re-engagement switch SAS CONT.
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Training Manual
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yaw SAS - Locations
05 – Flight Control
5.10.1 Yaw Stability Augmentation System
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05 – Flight Control
5.10 Three Axis Stability Augmentation System SAS
5.10.2 Fiber Optical Gyro FOG
EC135 Classic 
B1 
Training Manual
05 – 76Iss. August 2018For instruction only
5.10.2 Fiber Optical Gyro FOG
The fiber optical gyro (FOG) is installed below the engine deck within 
the structure of the tail boom attachment cone between frame 7 and 
frame 8. It can be accessed when the avionic plate is lowered. 
The fiber optical gyro controls helicopter acceleration around the 
vertical axis. A variation in the yaw rate within a specific frequency 
bandwidth causes the FOG to transmit an electrical stabilizing signal 
to the yaw actuator. The FOG is equipped with an electronic validity 
control loop to monitor the operational readiness of the system.
yaw Actuator (SEMA) 
The yaw actuator is installed in the Fenestron® structure. It is an 
actuator with an integral position feedback (Smart Electro-Mechanical 
Actuator SEMA). It convertsthe stabilizing signal produced by the 
FOG into a corresponding mechanical input to the tail rotor control 
linkage. 
The series–connected yaw actuator operates between the Flexball 
control cable and the hydraulic Fenestron® actuator. In consequence, 
stabilizing inputs from the yaw stability augmentation system and the 
control inputs from the pilot are superimposed on each other.
Following a stabilizing input, the yaw actuator automatically recenters 
within its maximum stabilizing stroke range to ensure full stabilizing 
input authority. 
Circuit Breaker yAW SAS 
The circuit breaker YAW SAS is located in the top right–hand section 
of the overhead panel. 
Switch SAS DCPL 
The cut-off switch SAS DCPL is located on the extreme left on the 
upper end of the cyclic stick grip. 
In the case of malfunction of the yaw actuator, the system can be 
disengaged through the cut–off switch SAS DCPL. The cut–off switch 
interrupts the engage signal to the FOG. 
Switch P&R/P–D/y RST 
The re-engagement switch P&R/P–D/Y RST is located in the top 
left--hand corner of the cyclic stick grip and is used to reactivate the 
system after the cut-off switch has been operated (reactivation is also 
possible by pulling and depressing the circuit breaker P/R SAS). The 
re-engagement switch reconnects the engage signal to the FOG.
CDS/CPDS Display 
The Caution YAW SAS appears in the MISC field if the Yaw SAS is 
decoupled.
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EC135 Classic 
B1 
Training Manual
05 – 77Iss. August 2018For instruction only
Functional Schematic - yaw SAS
05 – Flight Control
5.10.2 Fiber Optical Gyro FOG
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05 – Flight Control
5.10 Three Axis Stability Augmentation System SAS
5.10.3 Pitch & Roll Stability Augmentation System
EC135 Classic 
B1 
Training Manual
05 – 78Iss. August 2018For instruction only
5.10.3 Pitch & Roll Stability Augmentation System
General
The pitch and roll SAS, which is also an independent system, is used 
for stabilizing the attitude of the helicopter about the longitudinal and 
lateral axes. It applies limited authority stabilizing inputs to the main 
rotor controls.
System Components 
The pitch and roll SAS consists of the following components:
 – pitch and roll SAS computer 
 – electro-hydraulic actuators (EHA) (2 off)
 – circuit breaker P/R SAS for 28 V DC
 – circuit breaker ROLL SAS and PITCH SAS for 26 V AC / 
400 Hz 
 – cut-off switch SAS DCPL 
 – re-engagement switch P&R/P-D/y RST 
 – 2 attitude gyros or GH14 horizons or AHRS1. 
Pitch and Roll SAS Computer
The pitch and roll SAS computer is located in the left-hand side 
channel in the floor structure and uses the input signals from the 
attitude gyros to compute the stabilizing input signals for the electro-
hydraulic actuators (EHA). An integral electronic validity control 
loop within the SAS computer monitors operational readiness of the 
system. Position signals fromboth trimactuators are used by the SAS 
computer to determine whether the pilot is overriding an SAS control 
input. This prevents the SAS from working against pilot stick inputs. 
A position sensor (LVDT) in the electro–hydraulic actuators (EHA) 
supplies the SAS computer with actuator position feedback signals. 
Electro-Hydraulic Actuators 
Both the electro–hydraulic actuator (EHA) and the mechano-hydraulic 
actuator (MHA) are integrated into the main rotor actuator housing.
The electro-hydraulic actuators (EHA) in the pitch and the roll axes 
are converting the electrical stabilizing signals to mechanical inputs. 
When the servo valve is excited, a hydraulic control piston operates 
to move the control spool of the mechanical-hydraulic actuator MHA, 
thereby adding stabilizing inputs to theMHA of the respective axis. 
As a result, the stabilizing inputs from the pitch and roll SAS are 
superimposed on the pilot stick inputs. 
Following a stabilizing input, the EHA automatically recenters within 
its maximum stabilizing stroke range to ensure full stabilizing input 
authority. 
Circuit Breaker P/R SAS (DC System) 
The circuit breaker P/R SAS is located in the upper LH section of the 
overhead panel. The busbar PP10E supplies the P&R SAS system 28 
VDC through the circuit breaker P/R SAS.
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EC135 Classic 
B1 
Training Manual
05 – 79Iss. August 2018For instruction only
Pitch& Roll SAS - Locations
05 – Flight Control
5.10.3 Pitch & Roll Stability Augmentation System
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05 – Flight Control
5.10 Three Axis Stability Augmentation System SAS
5.10.4 Circuit Breaker Roll SAS and Pitch SAS (AC System)
EC135 Classic 
B1 
Training Manual
05 – 80Iss. August 2018For instruction only
5.10.4 Circuit Breaker Roll SAS and Pitch SAS (AC 
System)
The SAS computer is also supplied with 26 V AC / 400 Hz from busbar 
26 V AC BUS I and II through the circuit breaker ROLL SAS and 
PITCH SAS. The circuit breaker ROLL SAS is located in the upper LH 
section, the circuit breaker PITCH SAS in the upper RH section of the 
overhead panel. 
The system is operative when its power supply is on. It becomes 
inoperative when the power supply is interrupted by pulling one of the 
three circuit breakers.
Cut–Off Switch SAS DCPL 
The cut–off switch SAS DCPL is located on the extreme left on the 
upper end of the cyclic stick grip. 
The system can be disengaged by actuating cut–off switch SAS DCPL. 
The cut–off switch interrupts the engage signal to the SAS computer.
Re-engagement Switch P&R/P–D/y RST 
The re-engagement switch P&R/P–D/Y RST is located in the top 
left hand corner of the cyclic stick grip and used to reactivate the 
system after the cutoff switch has been actuated (reactivation is also 
possible by pulling and depressing the circuit breaker P/R SAS). The 
re-engagement switch reconnects the engaged signal to the SAS 
computer. 
Attitude Gyros 
The P/R SAS system requires attitude information in the pitch and roll 
axis. Depending on the equipment, this information comes from
 – vertical gyros underneath the floor panel
 – artificial horizon (e.g. GH14) 
 – Attitude and heading reference system AHRS 1 
All three different sensor types require AC power for the correct signal 
to the P/R SAS computer (analogue 400 Hz). 
CDS / CPDS Display 
The caution P/R SAS is displayed on the CDS / CPDS when the power 
supply is interrupted or a fault occurs in the EHS, SAS computer, or 
attitude gyro.
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EC135 Classic 
B1 
Training Manual
05 – 81Iss. August 2018For instruction only
Functional Schematic – Pitch and Roll SAS
05 – Flight Control
5.10.4 Circuit Breaker Roll SAS and Pitch SAS (AC System)
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05 – Flight Control
5.10 Three Axis Stability Augmentation System SAS
5.10.5 Pitch Damper (DPIFR)
EC135 Classic 
B1 
Training Manual
05 – 82Iss. August 2018For instruction only
5.10.5 Pitch Damper (DPIFR)
General
For Dual Pilot IFR certification an additional pitch damper has to be 
installed in order to compensate excessive pitch changes (e.g. EHA 
runaway).
System Components 
The pitch damper system comprises the following:
 – pitch gyro 
 – pitch SEMA
 – switch P&R/P-D/Y RST
 – circuit Breaker PITCH DAMPER 
 – indication P DAMPER.
Pitch Gyro
The pitch rate gyro (FOG, Fibre Optic Gyro) is installed in the LH side 
channel near to the SAS computer and measures angular changesof 
the helicopter in its pitch axis. 
The pitch rate gyro provides digital signals to control the pitch SEMA.
The power supply for the system is provided via the P DAMPER circuit 
breaker located in the overhead panel. 
Pitch SEMA 
The pitch SEMA is integrated in the horizontal control rod which leads 
from the upper guidance unit to themain rotor actuator for longitudinal 
control. 
The SEMA is installed in series with the pilot’s longitudinal control. It 
sends limited control signals directly to the EHA without the cyclic stick 
being moved. 
The actuator and a servo control loop are contained in the pitch SEMA 
casing. 
The electronics of the servo control loop includes a monitoring system 
which detects and corrects internal defects in the servo control loop 
itself and control signal errors.
With the P/R SAS active, the pitch SEMA acts as a pitch damper, too. 
An EHA runaway will not be detected by the SAS, therefore the SEMA 
will recover this situation. 
Switch P&R/P–D/y RST 
The switch P&R/P-D/Y RST is located on the left on the upper end 
of the cyclic stick grip. The 3–way switch is used to reengage the 
individual functions. 
Circuit Breaker 
The circuit breaker PITCH DAMPER is installed in the overhead panel 
and supplied via the ESS. BUS II. 
Indication PITCH DAMPER 
A failure of the pitch damper is indicated with the caution P DAMPER 
in the MISC field of the CDS/CPDS. HC with early CDS versions are 
equiped with an caution light PITCH DAMPER on the left side of the 
Warning Unit.
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EC135 Classic 
B1 
Training Manual
05 – 83Iss. August 2018For instruction only
Pitch Damper - Locations, Indication and Switch
05 – Flight Control
5.10.5 Pitch Damper (DPIFR)
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05 – Flight Control
5.11 Autopilot System EC135
5.10.5 Pitch Damper (DPIFR)
EC135 Classic 
B1 
Training Manual
05 – 84Iss. August 2018For instruction only
5.11 Autopilot System EC135
General
The EC 135 AFCS consists of a 3–axis SAS (Yaw SAS, Pitch & Roll 
SAS) a pitch damper and an autopilot system.
The yaw SAS
Consists of a yaw rate gyro (FOG) and a “smart” electro-mechanical 
actuator (SEMA). It provides rate damping about the helicopter’s 
vertical axis. 
The Pitch & Roll SAS 
Consists of a P&R SAS computer (SAS 2000), a longitudinal (pitch) 
and a lateral (roll) electro-hydraulic actuator (EHA). 
The P&R SAS provides short term attitude hold and rate damping. 
It has a stand-by back up function when operated with the AFCS. 
The EHAs operate in series with the cyclic controls and introduce a 
limited authority by motion directly into the hydraulic boost. The SAS 
computer uses attitude information from AHRS 1. 
The Pitch Damper 
Consists of a pitch rate gyro (FOG) and a longitudinal SEMA. It 
provides pitch damping also as redundancy for IFR to lesson the 
effect of a Pitch SAS (EHA) defect.
The Autopilot System
Consists of the Autopilot Module (APM 2000) and the Autopilot 
Mode Selector (APMS 2000). For additional control authority and 
redundancy, a second actuator is installed in the roll axis (roll SEMA) 
and in the yaw axis (yaw SEMA). 
A precondition for operating of the AFCS is the 3–axis SAS and the 
pitch damping system. Nevertheless, the 3–axis SAS and the pitch 
damping system can be operated as a “stand alone” system without 
the AFCS under VFR and DPIFR rules. 
The 3–axis autopilot system of the EC 135 is installed as flight control 
system for D/SPIFR operation. 
It provides:
 – Digital SAS (AP SAS)
 – Auto trim function (A. TRIM)
 – Heading hold (HDG)
 – Altitude hold (ALT)
 – Airspeed hold (IAS)
 – Vertical speed hold (VIS)
 – Altitude acquire (ALT.A)
 – VOR navigation (NAV (VOR))
 – Long range navigation (NAV (NMS))
 – Localizer mode (APP (LOC))
 – VOR approach mode (APP (VOR.A) 
 – Glide slope (GS)
 – Go around mode (GA)
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EC135 Classic 
B1 
Training Manual
05 – 85Iss. August 2018For instruction only
AFCS - Installation Locations
05 – Flight Control
5.11 Autopilot System EC135
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05 – Flight Control
5.11 Autopilot System EC135
5.11.1 Installation Locations
EC135 Classic 
B1 
Training Manual
05 – 86Iss. August 2018For instruction only
5.11.1 Installation Locations
APM
The autopilot module is integrated in the PELICAN rack. The rack is 
installed on the avionics deck in the aft, upper section of the cargo 
compartment. The APM consists of two computers integrated on a 
single printed circuit board. Both computers perform continuous 
crosstalk to verify and ensure its correct operation.
ADC
The air data computers 1/2 are respectively installed in the LH and RH 
side channels of the helicopter. They are connected to the respective 
pitot/static system to give information about ALT/IAS/VS.
Pitch FOG 
The pitch fibre optic gyro is installed in the LH side channel of the 
helicopter. This laser gyro operates in the longitudinal axis and 
provides digital signals for control of the pitch damper (SEMA). 
yaw FOG 
The yawfibre optic gyro is installed in the aft, upper section of the 
cargo compartment near to the rear structure attachment cone. It 
gives yaw rate signals to the yaw SEMA 1 to stabilize the yaw axis.
APMS 
The autopilot mode selector is integrated below the instrument 
panel in the slanted console or in the center console. It comprises all 
necessary buttons and knobs to engage the autopilot and to select the 
various upper modes. 
Pitch & Roll SAS Computer 
The pitch & roll SAS computer is installed in the LH side channel of 
the helicopter. It uses the input signals from the AHRS 1 to compute 
the stabilizing input signals for the electro-hydraulic actuators (EHA). 
The P&R computer is also supplied with 26 VAC / 400 Hz (only from 
inverter 2) in addition to DC power supply. 
Pitch SEMA 
The pitch SEMA is installed in the horizontal control rod of the pitch 
axis, behind the overhead panel. It converts the pitch stabilizing signal 
into a correspondingmechanical input only in case of a runaway of 
the pitch EHA. With AP engaged it acts as a normal series actuator + 
A.TRIM. 
Roll SEMA 
The roll SEMA is installed in the control rod of the roll axis, directly in 
front of the hydraulic actuator. This actuator converts the roll stabilizing 
and/or control signal into a corresponding mechanical input to the roll 
control rod, only with the AP engaged. 
yaw SEMA 
The two yaw SEMAs are respectively mounted on each end of the 
control rod for the Fenestron® servo actuator. They convert the yaw 
stabilizing and/or control signal into a corresponding mechanical input 
to the yaw control rod. Yaw SEMA 2 is only active with AP+A.TRIM 
engaged.
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EC135 Classic 
B1 
Training Manual
05 – 87Iss. August 2018For instruction only
Pitch / Roll SEMA/EHA
05 – Flight Control
5.11.1 Installation Locations
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05 – Flight Control
5.11 Autopilot System EC135
5.11.2 EHA
EC135 Classic 
B1 
Training Manual
05 – 88Iss. August 2018For instruction only
5.11.2 EHA
The electro-hydraulic actuators for the pitch and roll axes are 
installed directly in the hydraulics of the main rotor actuator. They are 
commanded by or via the Pitch & Roll SAS computer.
Trim Motors (Parallel Actuators)
Trim Motors (Parallel Actuators) The trim motors for pitch/roll are 
installed below the cabin