Flight Controls System [Question Bank Airbus A320] – Page 1

1. How many flight control computers Airbus A320 has?

Airbus A320 has 7 flight control computer.

2 ELACs

Elevator Aileron Computer

3 SECs

Spoilers Elevator Computer

2 FACs

Flight Augmentation Computer

For normal elevator and stabilizer control. Aileron control For spoilers control and standby elevator and stabilizer control For electrical rudder control

In addition 2 FCDC (Flight Control Data Concentrates) which acquire data from ELACs and SECs and sed it to electronic instrument system (EIS) and centralized fault display system (CFDS).

2. How is pitch control achieved in Airbus A320 aircraft?

Pitch control is achieved by 2 elevators and 1 Trimmable Horizontal Stablizer (THS)

3. How does ELAC 1+2 failure case affects the flight controls?

In case of ELAC 1+2 failure both the ailerons and THS(Trimmable Horizontal stabilizer) motor 1 is lost.

4. How is priority set for THS motors?

THS has 3 electric motors. THS control has following priority sequence:

  1. ELAC2 controls THS by motor number 1
  2. in case of ELAC 2 failure ELAC 1 controls THS by motor number 2
  3. in case of ELAC 1+2 failure, SEC1 or SEC2 (depending on status of associated circuits) control THS via motor number 2 or 3

Note: Mechanical control of THS is available from pitch trim wheel at any time if either green or yellow hydraulic system is functioning and also mechanical control has priority over electrical control.

5. How is roll control achieved in Airbus A320 aircraft?

Roll control is achieved by 1 aileron and 4 spoiler per wing. ELAC 1 normally control aileron and ELAC 2 is used for redundancy. If both ailerons fail, they enter into damping mode.

6. How many spoilers do A320 has and how are the panels divided?

Airbus A320 has 5 spoilers per wing. Their usage is as under:

  • Spoiler 2, 3 and 4 for speed brakes
  • Spoiler 2, 3, 4 and 5 for roll control
  • All five surfaces acts as ground spoilers

7. What all flight control surfaces are unavailable in case of SEC1 inoperative (departure under MEL)?

Spoiler 3 and 4 are controlled by SEC1, and will not be available for SEC1 inoperative MEL.

8. Which spoiler surfaces act as speed brakes surfaces?

Spoiler 2, 3 and 4 acts as speed brake surfaces.

9. What happens if we pull speed brakes in Config Full?

Speed brakes remains retracted and amber light flashes on ECAM memo.

10. What happens if config full is selected when speed brakes were already out?

Speed brakes retract automatically in this situation.

11. What happens to spoilers in case of electrical and hydraulic failure?

  • In case of electrical failure, spoilers retract to zero.
  • In case of hydraulic failure, spoilers stay in original position or go down by aerodynamic force.

12. Half speed brake lever position give maximum deflection with AP ON. Is this statement correct?

Yes

13. What happens if any spoiler surface on fails to operate?

When there is failure of any spoiler surface, the same surface on opposite wing also gets inhibited to avoid asymmetry.

14. Under what all conditions are spoilers inhibited?

  • SEC 1 + 3 Fault
  • L or R Elevator Fault
  • Angle of Attack Protection Active
  • Flaps Full
  • Thrust Lever MCT
  • A Floor Active

15. Explain extension and retraction logic of ground spoilers.

Extension logic of A320 ground spoilers can be broadly categorize as under:

Full Extension – RTO Phase Full Extension – Landing Phase Partial Extension
  • ground spoilers armed -> wheel speed exceeds 72 kt -> extend when both thrust levers are set to idle
  • ground spoilers NOT armed -> wheel speed exceeds 72 kt -> extend as soon as reverse is selected on one engine

ARM is done for earliest extension of ground spoilers

  • speed brake lever not in retracted position or ground spoilers armed and
    a – both main gear on ground
    b – both thrust levers at or below idle OR reverse selected at least on one engine
  • speed brake retracted but ground spoilers not armed and
    a – both main gear on ground
    b – reverse selected on at least one engine

Extra caution is required for touch and go condition. Don’t arm spoiler and also ensure they are retracted

Phased Lift Dumping (PLD) function is sued to accelerate full extension of spoilers.

  • speed brake lever not in retracted position or ground spoilers armed and
    a – one main gear on ground
    b – both thrust levers at or below idle
  • speed brake retracted but ground spoilers not armed and
    a – one main gear on ground
    b – reverse selected on at least one engine

16. How is Yaw Control Achieved in Airbus A320 aircraft?

FAC uses ELAC computed data for processing yaw orders(turn coordination) for rudder. This data is also used for damping yaw oscillation.

17. Rudder deflection is the function of speed. Is this statement correct?

YES.

18. How does FAC 1+2 failure case affects the flight controls?

In case of FAC 1+2 failure, rudder travel limiter, rudder trim control and yaw dampers are lost.

19. Which all flight control surfaces are lost in case of dual hydraulic failure (G + Y) occurs?

Yaw damper, stabilizer, spoiler 1, 2, 4 and 5 and flaps are lost for G + Y failure.

20. What happens to flight controls if all three hydraulic systems fail?

No flight control is available in case of all three hydraulic systems fail.