Flight Control Computers

Question 1

What does FAC stand for? How many do we have?

Answer 1

Flight Augmentation Computer. We have 2 FAC’s.

Question 2

What are the four main functions of the FAC’s?

Answer 2

Vol 3, Auto flight - flight augmentation

1.) Yaw functions
2.) Flight envelope functions
3.) Low energy aural alert
4.) Windshear detection function

Question 3

What YAW functions do the FAC’s perform?

Answer 3

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

-Yaw damping
-Turn coordination
-Rudder trim
-Rudder travel limit

Question 4

What flight envelope functions do the FAC’s perform?

Answer 4

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

-PFD speed scale management
-Minimum/maximum speed computation
-Maneuvering speed computation
-Alpha floor protection

Question 5

When a FAC is disengaged (FAC button set to OFF), and the FAC is still functioning properly, does the FAC continue to do anything for you?

Answer 5

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

Yes, the flight envelope functions (PFD speed scale management and alpha floor protection) of the FAC remain active

Question 6

Which FAC normally controls the yaw functions of the aircraft?

Answer 6

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

FAC 1. But FAC 2 will take over in the event of any failures.

Question 7

Do the FAC’s do anything special during after an engine failure?

Answer 7

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

Yes, it assists with rudder application after an engine failure (short-term yaw compensation) when the auto pilot is engaged during takeoff and go-arounds.

Question 8

How far out of trim does the rudder need to be pressed before the AP turns off?

Answer 8

Vol 3, AUTO FLIGHT- FLIGHT AUGMENTATION

• 10º

Question 9

Does the rudder trim knob work when the AP is engaged?

Answer 9

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

No

Question 10

What happens to your rudder travel limit if both FAC’s fail?

Answer 10

Vol 3, The value of the rudder travel deflection is locked at the time of the second failure

Question 11

What happens to the rudder deflections limit when the slats are extended?

Answer 11

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

The rudder deflection limit is set to the low speed limit (maximum authorized deflection)

Question 12

Which FAC supplies PFD speed information to which PFD?

Answer 12

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

FAC 1 supplies PFD1 and FAC 2 supplies PFD 2

Question 13

How do the FAC’s help ensure that the weight that’s entered into the MCDU is correct?

Answer 13

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

The FAC’s compute the aircrafts GW and CG based on aerodynamic data. This GW is then cross checked with the FMS gross weight. If there’s a large engorge difference between the two gross weights (FMS and FAC calculated), you’ll get the “CHECK GW” message on the MCDU.

Question 14

What piece of information from the FMS do the FAC’s use to compute the operating speeds? What would happen if both FMS’s failed and that piece of info was lost?

Answer 14

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

The aircrafts gross weight entered into the FMS is used by the FAC’s to calculate the operating speeds. If both FMS’s are lost, the FAC’s will revert to using a computed gross weight that is calculated based on aerodynamic data (AOA, speed/MACH, altitude, thrust, and CG)

Question 15

Which kind of windshear protection do the FAC’s provide?

Answer 15

Vol 3, AUTO FLIGHT - FLIGHT AUGMENTATION

Reactive windshear (“WINDSHEAR, WINDSHEAR”), not predictive windshear