DOC AIRBUS | AMM A320FFLIGHT CONTROL UNIT (FCU) - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The Flight Control Unit (FCU) comprises the auto flight control section and the EFIS control sections. It is located on the glareshield.
The FCU consists of two identical computers totally independent.
The computers (SIDE 1 and SIDE 2) have separate power supplies.
Each side is associated with the controls on the front panel of the unit.
The display is common to both sides, whereas the signals are routed via separate paths.
** ON A/C NOT FOR ALL The Flight Control Unit (FCU) comprises the auto flight control section and the EFIS control sections. It is located on the glareshield.
Flight Control Unit (FCU)The FCU consists of two identical computers totally independent.
The computers (SIDE 1 and SIDE 2) have separate power supplies.
Each side is associated with the controls on the front panel of the unit.
The display is common to both sides, whereas the signals are routed via separate paths.
2. Component Location
** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 2CA | FCU | 13VU | 210 | 22-81-12 | |
3. Component Description
A. Face of FCU FIN: 2-CA
The FCU comprises three panels:
The FCU comprises three panels:
- one center panel (auto flight control section) which features the controls and the displays associated with the AFS
- two symmetrical panels (EFIS control sections) located on the left side and on the right side of the center panel. These panels include the controls and the displays associated respectively with the Captain and the First Officer EFIS display units.
B. Architecture
Each part (or computer) of the FCU can manage the controls and the displays located on the front panel of the unit.
Architecture is configured to provide physical separation between the two channels and segregate electrical routing.
Each part (or computer) of the FCU can manage the controls and the displays located on the front panel of the unit.
Architecture is configured to provide physical separation between the two channels and segregate electrical routing.
4. System Description
A. Changeover
NOTE: After you open the two FCU circuit breakers (during the FCU removal procedure), you will continue to see the FCU displays for some time. This is because of the residual polarization of the liquid crystals.
B. System Functions
The FCU ensures the interface between the crew and the three following systems:
The reconfiguration logic is defined in the following table:
This logic enables the maximum availability of FCU functions.
Each channel receives all data required to ensure the three functions.
Reconfiguration for the activated channel therefore consists in connection of that channel to output interfaces via ARINC bus to the related control panel.
The FCU ensures the interface between the crew and the three following systems:
- AFS (Ref. NOTE)
- EIS LEFT
- EIS RIGHT
- channel B : EIS LEFT and AFS
- channel C : EIS RIGHT
The reconfiguration logic is defined in the following table:
| ----------------------------------------------------------------------------- |
| ! FAILED ! FUNCTIONS ! |
| ! CHANNEL ----------------------------------------------------------- |
| ! ! EIS LEFT and AFS ! EIS RIGHT ! |
| !---------------------------------------------------------------------------! |
| ! NONE ! B ! C ! |
| !-----------------!--------------------------------------!------------------! |
| ! B ! C ! C ! |
| !-----------------!--------------------------------------!------------------! |
| ! C ! B ! B ! |
| ----------------------------------------------------------------------------- |
This logic enables the maximum availability of FCU functions.
Each channel receives all data required to ensure the three functions.
Reconfiguration for the activated channel therefore consists in connection of that channel to output interfaces via ARINC bus to the related control panel.
C. Operational Interface
(1) Input signals
(a) Connections with the FMGCs
Channels B and C receive from each FMGC :
Channels B and C receive from each FMGC :
- FMGC OWN A bus
- hardwired discretes: confirmation of AP, FD and A/THR engagements
- a hardwired discrete: FCU validity detected by the FMGC
(b) ARINC feedbacks
For synchronization (Ref. para. C) and internal monitoring (Ref. para. D) purposes, the AFS, EIS CP-L and EIS CP-R output buses are looped back to the two channels.
For synchronization (Ref. para. C) and internal monitoring (Ref. para. D) purposes, the AFS, EIS CP-L and EIS CP-R output buses are looped back to the two channels.
(2) Output signals
(a) Discrete signals
The FCU delivers control data for AP1, AP2 and A/THR engagement to each FMGC in the form of hard-wired discretes.
Those data are issued directly from the engagement pushbutton switches without software processing.
Each pushbutton switch contains two contacts in order to duplicate the output signals.
The FCU delivers control data for AP1, AP2 and A/THR engagement to each FMGC in the form of hard-wired discretes.
Those data are issued directly from the engagement pushbutton switches without software processing.
Each pushbutton switch contains two contacts in order to duplicate the output signals.
(b) ARINC 429 bus
A bus is associated with each function performed by the FCU.
For segregation reasons transmission of data to the engines has required the creation of four identical outputs for the AFS.
The FCU therefore delivers a total of four ARINC buses.
Those are :
A bus is associated with each function performed by the FCU.
For segregation reasons transmission of data to the engines has required the creation of four identical outputs for the AFS.
The FCU therefore delivers a total of four ARINC buses.
Those are :
| AFS-1A * |
| AFS-1B * |
| AFS-2A * |
| AFS-2B * |
| (* :Identical content) |
D. Synchronization
In order to avoid display modifications during reconfigurations, the channel non-active on a given function synchronize on the values computed by the channel active on this function.
This is accomplished through wrap-around buses.
The passive channel permanently acquires, on this bus, the data computed by the active channel.
If the active channel is faulty, the activated channel is initialized with the data just acquired on the bus associated with the related function.
There is also synchronization, with aircraft in flight, after long power cuts.
In this case, the data used are those stored in the RAM (Random Access Memory) prior to power cutoff. The displays are thus maintained.
In order to avoid display modifications during reconfigurations, the channel non-active on a given function synchronize on the values computed by the channel active on this function.
This is accomplished through wrap-around buses.
The passive channel permanently acquires, on this bus, the data computed by the active channel.
If the active channel is faulty, the activated channel is initialized with the data just acquired on the bus associated with the related function.
There is also synchronization, with aircraft in flight, after long power cuts.
In this case, the data used are those stored in the RAM (Random Access Memory) prior to power cutoff. The displays are thus maintained.
E. System Monitoring
The FCU is monitored by :
In the event of a fault, the faulty channel disconnects itself (FCU HLTY/B or C discrete signal). As the remaining channels are prompted on its validity status, the reconfiguration process is engaged and a failure message is sent to the FWS.
The FCU is monitored by :
- a watchdog which checks the correct operation of the program of each computation channel
- the active FMGC which compares, for the channel active on the AFS function, the data received from the FCU with its transmitted data.
In the event of a fault, the faulty channel disconnects itself (FCU HLTY/B or C discrete signal). As the remaining channels are prompted on its validity status, the reconfiguration process is engaged and a failure message is sent to the FWS.
F. Power Up Test
The FCU power up tests are initiated automatically on the channels concerned (B/PS 1, C/PS 2) when the following conditions are met:
The FCU power up tests are initiated automatically on the channels concerned (B/PS 1, C/PS 2) when the following conditions are met:
- aircraft on ground (configuration confirmed by two data)
- restoration of electrical power after power cutoff longer than 5 s.
- safety tests
- verification of ARINC EEPROMs (Electrically-Erasable Read-Only Memory)
- validity check of external and internal pin programming functions.