FLIGHT AUGMENTATION COMPUTER (FAC) - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
The Flight Augmentation Computer (FAC) fulfills the functions given below:

A. Yaw Damper
The yaw damper function ensures:

In manual control, the accomplishment of the yaw orders from the elevator aileron computer (ELAC) (stabilization and manual turn coordination). It also provides a yaw-damping degraded law in the event of ELAC failure (alternate law).
In automatic control, the accomplishment of the autopilot orders from the Flight Management and Guidance Computer (FMGC) for:
. Turn coordination (ILS approach mode and roll out).
. Guidance (align and roll out).
It also ensures in automatic flight:
. Engine failure recovery.
. Yaw stability.
. Turn coordination (cruise).

B. Rudder Trim
The rudder trim function ensures:

In manual control:
. The accomplishment of the pilot trim orders from the manual trim control (control and reset)
In automatic control:
. The accomplishment of the autopilot orders (autotrim on the yaw axis)
. The generation and the accomplishment of the engine failure recovery function.

C. Rudder Travel Limiting
The rudder travel limiting function ensures:

The limitation of the rudder travel as a function of a predetermined law
The return to low speed limitation in case of loss of function as soon as the slats are extended.

D. Stop Rudder Input
The "stop rudder input" function ensures the activation of a new synthetic-voice cockpit message "STOP RUDDER INPUT". You can hear this message two times consecutively when inappropriate rudder pedal inputs are detected at highspeed.

E. Calculation of Characteristic Speeds and Protection of Flight Envelope
The FAC generates, independently of the engage status of the pushbutton switches, different functions necessary to:

The control of the speed scale on the PFDs
The adaptation of gains for the FMGC and ELAC
The distribution of signals necessary to the FMGC control laws
The flight envelope protection in automatic flight (speed limits for the FMGC, alpha floor for the autothrust)
The display of the rudder trim order and the rudder travel limiter position if available
The windshear detection (option activated by pin program)

The low energy detection (option activated by pin program).

The Runway Overrun Prevention System (ROPS) (option activated by pin program).

F. Maintenance
The Centralized Fault-Display System (CFDS) has two modes of operation (Ref. 22-90-00):

(1) Normal mode
In this mode, the system FIDS (BITE concentrator) stores all the analysis results of the various BITE. It may perform a crosscheck to determine the faulty LRU. It transmits the reference of the LRUs which have failed during the current flight to the Centralized Fault-Display Interface-unit (CFDIU).

(2) Menu mode
In this mode:

It is possible to activate the various AFS tests and to display maintenance snapshots.

** ON A/C NOT FOR ALL

2. Component Location

FAC - Component Location (Cockpit) ** ON A/C NOT FOR ALL

FAC - Component Location (Electronics Rack)

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C ALL
1CC1	FAC-1	83VU	127	22-66-34
1CC2	FAC-2	84VU	128	22-66-34
8CC	P/BSW-RUD TRIM/RESET	110VU	210	22-62-12
9CC	CTL SW-RUDDER TRIM	110VU	210	22-62-11
12CC1	P/BSW-FLT CTL/FAC1	23VU	211	22-62-00
12CC2	P/BSW-FLT CTL/FAC2	24VU	212	22-62-00
17CC	IND-RUDDER TRIM	110VU	210	22-62-21

** ON A/C NOT FOR ALL

3. System Description

FAC - Component Layout ** ON A/C NOT FOR ALL

The system comprises:

Two computers
Two yaw damper servo-actuators
A rudder trim actuator assembly with two actuators and associated relays
A rudder travel-limitation unit with two motors and associated relays
Two FLT CTL/FAC 1 and FAC 2 engage pushbutton switches
Two self-locking relays integrated in the aircraft wiring
A RUD TRIM Control Panel
Indications and warnings on the ECAM display units related to the position of the control surfaces.

[Rev.10 from 2021] 2026.04.01 06:47:27 UTC