DOC AIRBUS | AMM A320FFLIGHT MANAGEMENT AND GUIDANCE COMPUTER (FMGC) - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. General
The Flight Management and Guidance Computer (FMGC) is a digital computer to 8MCU in conformity with ARINC Specification 600.
It is to be noted that some boards in the computer are equipped with a memory module. The access to these modules is from the outside of the unit.
The computer consists of two separate parts : a command channel and a monitoring channel.
The command channel ensures two functions : the management of the flight and the guidance.
The monitoring channel only ensures the guidance function.
The two channels are physically separate :
For the GUIDANCE function, the engage logic of the AP, FD and A/THR systems in command and monitoring channels is achieved in hard-wired circuitry.
** ON A/C NOT FOR ALL The Flight Management and Guidance Computer (FMGC) is a digital computer to 8MCU in conformity with ARINC Specification 600.
It is to be noted that some boards in the computer are equipped with a memory module. The access to these modules is from the outside of the unit.
FMGC - Front PanelThe computer consists of two separate parts : a command channel and a monitoring channel.
The command channel ensures two functions : the management of the flight and the guidance.
The monitoring channel only ensures the guidance function.
The two channels are physically separate :
- each channel has its own power supply unit.
- the electronic boards assigned to each channel are located in different zones in the computer unit.
- the electrical routings are separate.
- the pin connections at the output connectors are duplicated and separate.
For the GUIDANCE function, the engage logic of the AP, FD and A/THR systems in command and monitoring channels is achieved in hard-wired circuitry.
2. Component Location
** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 1CA1 | FMGC-1 | 824 | 127 | 22-83-34 | |
| 1CA2 | FMGC-2 | 84VU | 128 | 22-83-34 | |
3. System Description
A. Command Channel
(1) Flight management
The FM card assembly is set on only one slot of the FMGC. This FM card assembly comprises a Processor card, a Memory card and an I/O controller card.
The FM card assembly is set on only one slot of the FMGC. This FM card assembly comprises a Processor card, a Memory card and an I/O controller card.
(a) Processor card (CPM = Core Processing Module)
This CPM fulfills all the flight management functions.
This module exchanges data:
This CPM fulfills all the flight management functions.
This module exchanges data:
- with the I/O controller card through the Inter-Module Memory (IMM)
- with the FG/FE through the FM/FG common memory.
(b) Memory card
this card is plugged to the CPM card and provides:
this card is plugged to the CPM card and provides:
- FM/FG common memory
- Flash data memory
- Battery-backed memory.
(c) I/O controller card (IOM = Input Output Module)
This card consists of two lanes (IOC 1 and IOC 2).
Each lane is comprised of :
This bus allows the FMS to be run in dual mode.
This card consists of two lanes (IOC 1 and IOC 2).
Each lane is comprised of :
- one processor
- Flash Memory
- dual port RAM (called Inter Module Memory IMM)
- several I/O ports (ARINC 429, RS-485, Ethernet, RS232).
- system synchronization with the FG timing
- generation of the CPM host interrupt signal for partition scheduling
- synchronization between IOM and CPM.
This bus allows the FMS to be run in dual mode.
(2) Guidance function
(a) Digital part
This part uses two processors : the INNER LOOP processor and the GUIDANCE COMMAND processor.
The dialogue between the two processors is performed through a shared memory.
The correct running of the program is checked by a watchdog. The result is directly taken into account in the system engagement hardwired logic on the EXTENSION COM board.
Safety tests are activated at power-up when the aircraft is on the ground.
The guidance part, command channel, is integrated on three boards:
This part uses two processors : the INNER LOOP processor and the GUIDANCE COMMAND processor.
The dialogue between the two processors is performed through a shared memory.
The correct running of the program is checked by a watchdog. The result is directly taken into account in the system engagement hardwired logic on the EXTENSION COM board.
Safety tests are activated at power-up when the aircraft is on the ground.
The guidance part, command channel, is integrated on three boards:
- a ILCPU (Inner Loop CPU)
- a CPU AFS
- an EXTENSION COM
1 ILCPU board
This board which includes the INNER LOOP processor is equipped with a memory module.
It ensures the following functions:
This board which includes the INNER LOOP processor is equipped with a memory module.
It ensures the following functions:
- ARINC acquisition of the peripherals for the INNER LOOP processor and transmission to the GUIDANCE processor.
- transmission of data to the peripherals by means of two ARINC buses : bus A (high speed) and bus B (low speed).
These buses are looped back on the GUIDANCE MONITOR for monitoring purposes. - computation of the AP, FD and A/THR inner loops control laws and vote of the AP signals between the command and monitoring channels
- monitoring through comparison of the AP signals between the two channels.
2 The GUIDANCE part is integrated in the other two boards in the command channel.
The CPU AFS board includes a memory module.
The GUIDANCE part ensures the functions below:
The CPU AFS board includes a memory module.
The GUIDANCE part ensures the functions below:
- ARINC acquisition for the Flight Management (FM) and guidance functions either directly or through the INNER LOOP board
- dialogue with the FM part
- computation of the operational logic
- computation of the AP, FD and A/THR outer loop signals and transmission of these signals to the INNER LOOP processor
- transmission of the flight management parameters on the ARINC bus C
- monitoring of the alpha floor detection
(b) Hardwired logic
It is integrated in the EXTENSION COM board. It ensures the functions below:
It is integrated in the EXTENSION COM board. It ensures the functions below:
1 AP engage logic
Engagement of the AP function depends on:
Engagement of the AP function depends on:
- the software conditions of the AP function
- the status of the GUIDANCE logic (monitoring of peripherals, FMGC hardware, watchdog)
- the status of the long power failure from the power supply unit
- the activation of the AP pushbutton switch on the FCU.
2 A/THR engage logic
The operation is similar to that of the AP engage logic.
The operation is similar to that of the AP engage logic.
3 FD engage logic
Engagement of the FD function depends on:
Engagement of the FD function depends on:
- the software conditions of the AP function
- the status of the GUIDANCE logic
- the activation of the FD pushbutton switch.
4 FCU monitoring
This monitoring consists in reading, on the FCU bus, the data transmitted by the FMGC through the bus A. If an unhealthy operation is detected, the FCU FAIL signal is set to FAIL and causes the internal reconfiguration of the FCU between FCU 1 and FCU 2.
This monitoring consists in reading, on the FCU bus, the data transmitted by the FMGC through the bus A. If an unhealthy operation is detected, the FCU FAIL signal is set to FAIL and causes the internal reconfiguration of the FCU between FCU 1 and FCU 2.
(3) Power supply unit
The power supply unit delivers these voltages for the command channel:
However, the microprocessors must be able to restart at power restoration.
No flight data must be lost if the cutoff is less than 5 min.
The power supply unit delivers these voltages for the command channel:
- +5 V BATT from a battery which keeps the FM common memory supplied
- +15 V, -15 V, +5 V, +28 V from the filtered aircraft 28 V (Ref. AMM D/O 22-84-00-00).
These voltages are monitored by the program which takes into account their status.
A circuit monitors the level of the 28 V and detects any power cutoff.
- Cutoffs less than 2 ms : these cutoffs have no impact on the operation of the FMGC.
- Short cutoffs : between 2 ms and 200 ms for the GUIDANCE part and between 2 ms and 4 s for the MANAGEMENT part.
The detection circuits provide the safeguard of the RAM memories and enable the microprocessors to restart at power restoration.
This transient must not cause disconnection of the AP, FD or A/THR systems - Long cutoffs : more than 200 ms for the GUIDANCE part or 4 s for the MANAGEMENT part.
However, the microprocessors must be able to restart at power restoration.
No flight data must be lost if the cutoff is less than 5 min.
B. Monitoring Channel (Guidance Only)
This channel includes a digital part and a hardwired logic as the GUIDANCE COMMAND channel.
This channel includes a digital part and a hardwired logic as the GUIDANCE COMMAND channel.
(1) Digital part
This part is integrated on two boards:
It ensures these functions:
This part is integrated on two boards:
- a CPU AFS board
- an EXTENSION MON board
It ensures these functions:
- ARINC acquisition of GUIDANCE peripherals
- computation of the operational logic
- computation of the AP/FD outer loop signals for the monitored modes
- computation of the inner loops control laws and vote of the AP signals between the command and monitoring channels.
- transmission of computed data to the command channel through a low-speed ARINC bus called INTERNAL bus
- monitoring of the AP/FD signals through comparison with the command signals
- monitoring of the alpha floor detection.
(2) Hardwired logic
It is identical with the logic of the command channel although it does not include the FCU monitoring circuits.
It is identical with the logic of the command channel although it does not include the FCU monitoring circuits.
(3) Power supply unit
It is identical with the power supply unit of the command channel although it does not include a 5 V battery.
It is identical with the power supply unit of the command channel although it does not include a 5 V battery.