The trick of the Trade A320 Comunication System

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Material exclusivo para treinamento 
Elaborado por: 
Nome: Douglas Alves 
Cargo: Instrutor de Manutenção 
Formação: Engenheiro Eletricista / Técnico em manutenção de aeronaves CHT (GMP/CEL/AVI) 
 
 
GUIDE STUDENT TOPICS 
Communication System 
Description and Operation 
 
When you work on aircraft, make sure that you obey all the Aircraft Maintenance Manual (AMM) safety 
procedures. 
This will prevent injury to persons and/or damage to aircraft. Here is an overview of main safety 
precautions related to the communications system 
Although the HF antenna is mounted under the leading edge of the vertical stabilizer, the RF energy 
given out during transmissions can cause an explosion during refueling. DO NOT TRANSMIT during 
refueling 
 
The single aisle aircraft communication system has two sub-systems: 
- radio communication, 
- on-board communication. 
The radio communication systems are used for communications to and from the aircraft. 
 
The on-board internal communication system is divided into 4 functions: 
- Service interphone (on ground only) for maintenance technician communication with cockpit or cabin 
thanks to several jack connectors around the A/C, 
- Flight interphone for cockpit internal communication and also with the ground mechanic, 
- Passenger Address (PA) from the cockpit or from cabin crew stations for passenger announcements, 
- Cabin interphone for cabin crew or cabin crew/pilots communication. 
 
The radio communications system lets the crew communicate with ground stations and to other 
aircrafts through VHF Data Radio (VDR), High Frequency Data Radio (HFDR) and SATCOM if 
installed. 
The VHF transceivers are identical and interchangeable, as are the HF transceivers. VDR 1 and VDR 
2 are normally used by the flight crew for voice communications. VDR 3 is used for Air Traffic Service 
Unit (ATSU) functions, and is used as back-up voice communications in case of system 1 or 2 failure. 
The HF transceivers are used when the aircraft is beyond the useful range of the VHF radios. 
The SATellite COMmunication system (SATCOM) is composed of the Satellite Data Unit (SDU), 
The SATCOM is a multi channel aviation satellite communication system. It supplies worldwide mobile 
radio communications that can handle voice and data. 
 
The Radio Management Panels (RMPs) give the capability of tuning all communication radios. The 
frequencies are tuned by using the 2 concentric knobs. 
Any RMP can tune any communication radio but each one is normally dedicated to a particular radio. 
- RMP 1 is dedicated to VDR 1, 
- RMP 2 is dedicated to VDR 2, 
- RMP 3 is dedicated to VDR 3 and HF 1/HF 2 (if installed). 
 
There are three Audio Control Panels (ACPs). The ACPs allow for audio channel selection for both 
transmission and reception. Additionally, the ACP provides individual volume control for reception 
channels. ACP 1 is dedicated to the captain and ACP 2 is dedicated to the F/O. A third ACP is 
dedicated for a third occupant and may be used as a back up for captain or first officer in case of 
failure. 
As an option ACPs with a SATCOM function can be installed. 
The ACPs give to the flight crew the ability to communicate with ground personnel and cabin crew 
and annunciate calls to the flight deck. 
Material exclusivo para treinamento 
Elaborado por: 
Nome: Douglas Alves 
Cargo: Instrutor de Manutenção 
Formação: Engenheiro Eletricista / Técnico em manutenção de aeronaves CHT (GMP/CEL/AVI) 
 
 
Calls to the flight deck can be made from any of the cabin attendant handsets. Mechanic calls can 
also be made from the External Power Control Panel. This will cause a buzzer to sound and a CALL 
light to come on, on the ACPs. 
 
Of the four on-board communication systems, two Cabin Intercommunications Data System (CIDS) 
directors control three of the four functions. The CIDS directors manage the following on -board 
communication functions: 
- PA system for passenger announcements (from the cockpit or from cabin crew stations), 
- cabin interphone system for crew communication (cabin together or with cockpit), 
- service interphone. 
The CIDS directors do not manage the flight interphone. 
The cabin crew can also manage these functions, through the In Flight Entertainment System (IFES), 
Video Announcements (VAs) or optionally through entertainment (video and audio). 
 
This system allows the flight crew members to communicate among themselves and with the ground 
mechanic. 
 
The heart of the audio system is the Audio Management Unit (AMU). It routes the signals generated 
by the crew and directs the signals to and from the appropriate radio or interphone system. 
The AMU has a decoding unit called SELective CALling (SELCAL). It lets aural and visual indications 
on the ACP with an amber CALL indication to alert the flight crew for calls from ground stations. When 
the PA function is used from cockpit the audio signal is routed via the AMU to the CIDS director and 
from the director to the Decoder Encoder Units (DEUs) for distribution in the cabin. 
The CALLS panel lets the cockpit crew gain the attention of a ground mechanic or the cabin crew by 
triggering visual and audio signals. For mechanic call the horn will sound, for cabin crew a high low 
chime will be broadcast on respective areas. 
 
The CIDS includes two directors, a touch-screen Flight Attendant Panel (FAP), and the DEUs. The 
touch screen FAP controls and indicates the status of the CIDS. Integrated within the FAP are Cabin 
Assignment Module (CAM), On Board Replaceable Module (OBRM) and Prerecorded Announcement 
and Music (PRAM) in flash card format. 
 
No Portable Electronic Device (PED) pictogram" and "fasten seat belt" signs are controlled from the 
cockpit. The FAP audio page gives controls and displays for the PRAM. 
The PRAM can be a flash card type, directly plugged into the FAP. An audio reproducer 
(cassette/compact disc) can also be installed. 
Passenger Address (PA), BoardinG Music (BGM), Video Announcements (VAs) and PRAM functions 
can be provided to the passenger through the In Flight Entertainment System (IFES). 
 
The emergency evacuation command may be activated from the cockpit, from the purser station, and 
optionally from the Additional Attendant Panel (AAP). 
The EVAC signal can be reset from the cockpit, FAP, AAP. 
The FAP, EVAC CMD and EVAC RESET P/Bs are installed on the hard key panel to be available at 
any time regardless of the FAP page shown. 
 
On the EVAC panel in the cockpit, the EVAC switch lets the evacuation command be activated from 
the purser station and the cockpit, or from the cockpit only. 
 
In the CIDS, the FAP displays the current cabin status on the CABIN STATUS page. The CIDS and 
related cabin systems are controlled and monitored from the FAP by its related page. 
 
In this topic are described the purser station, the cabin crew station, and the area call panel. 
Each crew station has: 
- a handset, 
- an Additional Attendant Panel (AAP), 
Material exclusivo para treinamento 
Elaborado por: 
Nome: Douglas Alves 
Cargo: Instrutor de Manutenção 
Formação: Engenheiro Eletricista / Técnico em manutenção de aeronaves CHT (GMP/CEL/AVI) 
 
 
- an Attendant Indication Panel (AIP), 
- two switch panels installed adjacent to the middle RH at tendant station for an A321. 
- a switch panel,installed adjacent to the aft RH passenger door (A318/A319/A320). 
 
The Area Call Panel (ACP) indicates: 
- crew calls (pink steady or flashing), 
- passenger call (blue steady), 
- lavatory call (amber steady), 
- lavatory smoke detection (amber flashing). 
 
A Cockpit Door Surveillance System (CDSS) is installed on top of the wiring provisions to let the flight 
crew identify a person in front of the cockpit door and to survey the hidden cross section in the door 
number 1 area. 
 
The CDSS has the following components: 
- 3 "NTSC video format" black and white video cameras in the door number 1 area, 
- 1 ON/OFF P/BSW installed on the COCKPIT DOOR VIDEO panel, 
- 1 camera select momentary P/B installed on the COCKPIT DOOR panel 
 
The cockpit voice recorder records the last 2 hours of the flight crew conversations and 
communications and aural warnings. It records automatically in flight and on ground when at least 1 
engine is running and for 5 minutes after the last engine is shut down and also 5 minutes after aircraft 
energization. 
The Cockpit Voice Recorder (CVR) control panel gives CVR controls for manual erasure and test of 
the recording. 
 
All the communication sub-systems can be tested through the MCDU except the CVR system. 
 
The HF antenna is installed behind the leading edge of the vertical stabilizer. All the other antennae are 
installed on the outer skin of the aircraft. 
 
The SELCAL panel, AMU, HF and VHF Line Replaceable Units (LRUs) are in the aft avionics 
compartment. 
For data communication, optional VDR (VHF Data Radio) & HFDR (HF Data Radio) transceivers can be 
used. 
 
The SATellite COMmunication system (SATCOM) includes the Satellite Data Unit (SDU). 
The SDU is installed in the aft avionics rack 80VU. 
 
The Solid State Cockpit Voice Recorder is installed in the rear fuselage. 
 
The aircraft behaves like a Faraday cage and should be discharged. The static dischargers avoid static 
electricity discharging noise and ensure a good quality of radio transmission, without interference. The 
purpose of the static dischargers is: 
- to discharge the static electricity accumulated by the aircraft during its flight, 
- to supply better intelligibility on the HF and VHF system (avoid static electricity discharge noise). 
 
 
 
The disposition of the static dischargers is used for the dispatch of the static electricity. They are located 
around the aircraft extremities. 
 
If the aircraft has been struck by lightning the static dischargers are the first elements destroyed and they 
can be easily replaced. Two kinds of static dischargers are installed, depending on their localization on 
the aircraft: 
Material exclusivo para treinamento 
Elaborado por: 
Nome: Douglas Alves 
Cargo: Instrutor de Manutenção 
Formação: Engenheiro Eletricista / Técnico em manutenção de aeronaves CHT (GMP/CEL/AVI) 
 
 
- one with a straight mounting installed at the trailing edges, 
- one with a 30 degree angle mounting, installed at the tips. 
Two types of retainer are installed: 
- a flat retainer at the trailing edges, 
- an angular retainer at the tips. 
The two types are not interchangeable. 
 
Directors 1 and 2 are installed in avionics rack 80 VU. 
 
The CIDS includes two directors, a touch-screen Flight Attendant Panel (FAP) and Decoder/Encoder Units 
(DEU). The touch-screen FAP controls and shows the status of the CIDS. The Cabin Assignment Module 
(CAM), the On-Board Replaceable Module (OBRM) and the Prerecorded Announcement and Music 
(PRAM) flash cards are integrated in the FAP. 
 
DEUs type A and B are installed behind the ceiling panels. The number of DEUs installed can change in 
relation to the fuselage length and the configuration of passenger entertainment systems. On the A321 for 
example, a maximum of 17 DEU-As and 8 DEU-Bs can be installed. DEUs type A are not interchangeable 
with DEUs type B. 
 
Each attendant station has a handset for public announcement, interphone dialing and communication. The 
handset rests in a cradle. 
 
The handset and cradle fulfill the following functions: 
- the hook-off sensing, 
- the Push-To-Talk (PTT) switching, 
- the Passenger Address (PA) announcement, 
- the interphone. 
 
Electro Static Discharge (ESD) is generated by rubbing materials with each other. By moving over plastic 
materials (synthetic fibers), wearing synthetic fiber clothing, electrical charges build up on the body. Thus 
voltages of 12000 to 35000 volts can develop on a person. Touching connector pins of computer units, a 
discharge path is formed through wiring and components. Integrated Circuit (IC) chips can be partly 
damaged or totally destroyed. Rubbing materials from the "tribo-electris" series against each other and then 
separating them from each other causes a build-up of electrostatic charges. If the materials are far apart in 
the series, there will be a higher electric charge. 
 
Here are some precautions to avoid damage of electronic equipment by ESD. Line Replaceable Units 
(LRUs) that are sensitive to ESD are identified by a black and yellow label on equipment face.