AUTO FLIGHT - FLIGHT AUGMENTATION

Question 1

The aircraft has two flight augmentation computers (FACs) that perform four main functions:

Answer 1

• Yaw function
  ‐ Yaw damping and turn coordination
  ‐ Rudder trim
  ‐ Rudder travel limitation
• Flight envelope function
  ‐ PFD speed scale management
  ▪ Minimum/maximum speed computation
  ▪ Maneuvering speed computation
  ‐ Alpha-floor protection
• Low-Energy Aural Alert function 
• Windshear detection function 

Question 2

the FAC uses independent channels :

Answer 2

Yaw damper
Rudder trim
Rudder travel limit
Flight envelope

Question 3

Each FAC interfaces with the ___ when the APs are disengaged, or with the ___ when at least one AP is engaged.

Answer 3

elevator aileron computers (ELACs) / FMGS

Question 4

Both FACs engage automatically at power-up.
The pilot can disengage or reset each FAC (in case of failure) by means of a pushbutton on the flight control overhead panel.
When a FAC is disengaged (FAC pushbutton set off) but still valid, ___ function of the FAC remains active.

Answer 4

the flight envelope

Question 5

If both FACs are valid, FAC1 controls ___, and FAC2 is in standby.
FAC1 keeps the aircraft within the flight envelope through FD1 ; FAC2 performs this function through FD2.
If a failure is detected on any channel of FAC1, FAC2 takes over the corresponding channel.

Answer 5

the yaw damper, turn coordination, rudder trim, and rudder travel limit

Question 6

If both FACs are valid, FAC1 controls ___, and FAC2 is in standby.
FAC1 keeps the aircraft within the flight envelope through FD1 ; FAC2 performs this function through FD2.
If a failure is detected on any channel of FAC1, FAC2 takes over the corresponding channel.

Answer 6

the yaw damper, turn coordination, rudder trim, and rudder travel limit

Question 7

YAW DAMPING
Yaw damping stabilizes the aircraft in yaw and coordinates its turns.
In automatic flight (AP engaged) during takeoff and go around, it assists rudder application after

Answer 7

an engine failure (short-term yaw compensation).

Question 8

YAW DAMPING
Note: When the AP is engaged, the FMGS sends orders to the FAC to give :

Answer 8

‐ Yaw damping during approach
‐ Yaw control for runway alignment in ROLL OUT mode

Question 9

RUDDER TRIM
The rudder trim function :
‐ Executes trim orders, entered by the pilot by using the manual trim knob.
‐ When AP is engaged

Answer 9

▪ executes trim orders from the FMGS.
▪ Assists the system in recovering from engine failure (long-term yaw compensation) in all flight
guidance modes.
▪ If the pilot pushes the rudder more than 10 ° out of trim, it disengages the AP.

Question 10

RUDDER TRIM
Note: When the AP is engaged, the rudder trim knob is

Answer 10

inoperative : the master FMGC sends rudder trim orders to the FAC.

Question 11

RUDDER TRAVEL LIMITATION
This function limits rudder deflection is based on speed in order to

Answer 11

avoid high structural loads.

Question 12

If both FACs lose the rudder travel limitation function, the value of the rudder deflection limit is locked at the time of the second failure.
When the slats are extended, the FACs automatically set the rudder deflection limit at

Answer 12

the low-speed setting (maximum authorized deflection).

Refer Graph
Max Deflection
NEO : 140 kts
CEO : 160 kts

Question 13

FLIGHT ENVELOPE FUNCTION
As long as one Flight Augmentation Computer (FAC) is valid, it governs the flight envelope function, the rudder position display, and the rudder trim indication regardless of what the flight crew does with

Answer 13

the FAC pushbutton.

Question 14

The FAC controls the speed scale on the PFD
The FAC computes:

Answer 14

‐ The minimum and maximum speeds:
‐ The maneuvering speeds:

The FAC also computes the speed trend and displays it as an arrow on the PFD speed scale.

Question 15

FAC computes the operating speeds based on the

Answer 15

FMS gross weight.

In parallel, the FAC also computes its own GW and CG, based on aerodynamic data, which is used by the ELAC and the FMS for gross weight crosscheck (CHECK GW MCDU message), and as a backup for speeds computation in the case of dual FMS failure.

Question 16

The principle of the FAC GW/CG computation based on aerodynamic data is as follows:
‐ The FAC computes VS1G. From VS1G it computes the FAC GW which is also sent to the ELAC:
* When the aircraft is below 14 625 ft and 250 kt, it computes this from

Answer 16

current angle of attack, speed/Mach, altitude, thrust, and CG
* When the aircraft is above 14 625 ft or 250 kt, it computes this out of the GW, which it
has memorized and updated with a fuel consumption model set in the FAC.

Question 17

ALPHA-FLOOR PROTECTION
The Alpha-floor function automatically applies TOGA thrust, when

Answer 17

the angle of attack exceeds the Alpha-floor threshold (between αPROT and αMAX).
TOGA thrust is applied regardless of the thrust lever position and the A/THR engagement status.

Question 18

ALPHA-FLOOR PROTECTION ACTIVATION
The Alpha-floor function activates when one of the following conditions occurs:

Answer 18

‐ The angle of attack is above Alpha-floor (Alpha-floor depends on the aircraft configuration, and
the aircraft deceleration rate), or
‐ The side stick deflection is close to full back stick, with either:
‐ The pitch attitude protection active
or
‐ The angle of attack protection active

Question 19

ALPHA-FLOOR PROTECTION INHIBITION
The Alpha-floor protection is inhibited when one of the following conditions occurs:

Answer 19

‐ The AP/FD TCAS  mode is engaged, or
‐ THE AIRCRAFT AIRSPEED IS ABOVE M 0.6, OR
‐ One engine is inoperative with slats/flaps extended, or
‐ One EIU is failed, or
‐ Both SFCC1 and FMGC2 are failed, or
‐ Both SFCC2 and FMGC1 are failed, or
‐ Both FCU channels are failed, or
‐ Both FMGCs are failed, or
‐ ALTERNATE OR DIRECT LAW IS ACTIVE.

Question 20

LOW - ENERGY AURAL ALERT
An aural low-energy “SPEED SPEED SPEED” alert, repeated every 5 s, warns the flight crew that the aircraft’s energy level is going below a threshold under which the flight crew has to increase thrust, in order to regain a positive flight path angle through pitch control.
It is available in Configuration

Answer 20

2, 3, and FULL.

Question 21

LOW - ENERGY AURAL ALERT
The FAC computes the energy level with the following inputs:

Answer 21

‐ Aircraft configuration
‐ Horizontal deceleration rate
‐ Flight path angle.

Question 22

LOW - ENERGY AURAL ALERT
The aural alert is inhibited when:
‐ TOGA is selected, or
‐ Below 100 ft RA, or
‐ Above 2 000 ft RA, or
‐ Alpha-floor, or the ground proximity warning system alert is triggered, or
‐ In alternate or direct law, or
‐ If both radio altimeters fail.
During deceleration, the low-energy aural alert is triggered before

Answer 22

alpha floor (unless alpha floor is triggered by stick deflection). The amount of time between the two alerts depends on the deceleration rate.

Question 23

WINDSHEAR DETECTION FUNCTION
The windshear detection function is provided by the Flight Augmentation Computer (FAC) in takeoff and approach phase in the following conditions:

Answer 23

‐ At takeoff, 3 s after liftoff, up to 1 300 ft RA
‐ At landing, from 1 300 ft RA to 50 ft RA
‐ With at least CONF 1 selected.

Question 24

WINDSHEAR DETECTION FUNCTION
The warning consists of:
2 items

Answer 24

‐ A visual “WINDSHEAR” red message displayed on both PFDs for a minimum of 15 s.
‐ An aural synthetic voice announcing “WINDSHEAR” three times.

Question 25

The FACs generate the WINDSHEAR WARNING whenever

Answer 25

the predicted energy level for the aircraft falls below a predetermined threshold.

Question 26

WINDSHEAR DETECTION PRINCIPLES
The FACs express this energy level as an angle of attack and compare it with

Answer 26

an angle-of-attack threshold above which windshear conditions are most likely and pilot action is required.