DOC AIRBUS | TSM A320FFlap Alignment Fault
TASK 27-51-00-810-818-A
Flap Alignment Fault
1. Possible Causes
A. Referenced Information
3. Fault Confirmation
Subtask 27-51-00-710-061-A
Subtask 27-51-00-810-067-C
[Rev.8 from Aug 2018]
2026.04.04 04:39:13 UTC
Flap Alignment Fault
1. Possible Causes
- flap drive assembly
- flap-actuator
- interconnecting strut
- flap transmission assembly
- backlash
A. Referenced Information
| REFERENCE | DESIGNATION |
|---|---|
| AMM 27-51-44-820-001 | Adjustment of the Interconnecting Strut |
| AMM 27-54-00-200-001 | Detailed Visual Inspection of the Transmission Assembly |
| AMM 27-54-00-200-003 | Detailed Dimensional Check - Free Movement at the Trailing Edge of the Flaps |
| AMM 27-54-00-710-001 | Operational Test of the Flap System |
| AMM 27-54-00-820-001 | Adjustment of the Flap Drive System |
| AMM 27-54-49-000-008 | Removal of the Flap Track 1 to 4 Actuators |
| AMM 27-54-49-400-005 | Installation of the Flap Track 1 to 4 Actuators |
| AMM 27-54-55-000-001 | Removal of the Flap-Actuator Lever Assembly - Tracks 1 and 2 |
| AMM 27-54-55-000-002 | Removal of the Flap-Actuator Lever Assembly - Track 3 |
| AMM 27-54-55-000-003 | Removal of the Flap-Actuator Lever Assembly - Track 4 |
| AMM 27-54-55-400-001 | Installation of the Flap-Actuator Lever Assembly - Tracks 1 and 2 |
| AMM 27-54-55-400-002 | Installation of the Flap-Actuator Lever Assembly - Track 3 |
| AMM 27-54-55-400-003 | Installation of the Flap-Actuator Lever Assembly - Track 4 |
Subtask 27-51-00-710-061-A
A. Test
4. Fault IsolationNOTE: Some flap alignment faults can occur in flight (when the flaps are under an aerodynamic load), but do not occur during an operational test on the ground.
Thus when a flap alignment fault message (FLP 1(2) CHK LH(RH) MECH DRIVE) is shown on the Post Flight Report (PFR), but the initial test on the ground is OK (the flaps move and align correctly), it is necessary to continue with the fault isolation procedure. This is because some faults, in the interconnecting strut or flap transmission assembly, only show during flight.
Thus when a flap alignment fault message (FLP 1(2) CHK LH(RH) MECH DRIVE) is shown on the Post Flight Report (PFR), but the initial test on the ground is OK (the flaps move and align correctly), it is necessary to continue with the fault isolation procedure. This is because some faults, in the interconnecting strut or flap transmission assembly, only show during flight.
NOTE: This TSM-Task is also applicable if the fault message FLP LH(RH) PROX SNSR 1(2) 37CV (38CV,39CV,40CV) MISADJUSTMENT is shown at the same time as the fault message FLP 1(2) CHK LH(RH) MECH DRIVE.
(1) Do the Operational Test of the Flap System AMM 27-54-00-710-001: - if the initial test is not OK, do the fault isolation procedure in Para. 4.A.(1)
- if the initial test is OK, continue and do the fault isolation procedure in Para. 4.A.(5).
Subtask 27-51-00-810-067-C
A. Procedure
(1) Do a visual check of the alignment of the inboard and outboard flap surfaces, on the applicable wing:
(4) Replace the applicable flap-actuator , AMM 27-54-49-000-008 and AMM 27-54-49-400-005.
(a) If the fault continues, do step (5).
(5) If the operational test is OK and the flap surfaces are aligned, but an alignment fault message is shown on the original Post Flight Report, do step (6).
(a) If the fault continues, do step (7).
(7) Do the check of the flap drive system, AMM 27-54-00-820-001.
(a) Do the adjustment of the interconnecting strut again, AMM 27-51-44-820-001.
(b) If the fault continues, do step (8).
(8) Do a check of the flap transmission assembly , AMM 27-54-00-200-001.
(a) From the check of the transmission assembly:
(10) Do the operational test of the flap system, AMM 27-54-00-710-001.
(1) Do a visual check of the alignment of the inboard and outboard flap surfaces, on the applicable wing:
- if the flap surfaces are aligned, do step (5)
- if the flap surfaces are not aligned, do step (2).
NOTE: When a flap alignment fault occurs, the torque-limiters do not usually operate. If a torque-limiter has operated, it is possible that the related flap-actuator or flap-track mechanism is the cause of the alignment fault.
(2) Examine the flap-actuators and flap-track mechanism of the flap which is not aligned correctly AMM 27-54-00-200-001. - if there are no worn or damaged components, do step (4)
- if there are worn or damaged components, do step (3).
- for flap tracks 1 and 2, AMM 27-54-55-000-001 and AMM 27-54-55-400-001
- for flap track 3, AMM 27-54-55-000-002 and AMM 27-54-55-400-002
- for flap track 4, AMM 27-54-55-000-003 and AMM 27-54-55-400-003.
(4) Replace the applicable flap-actuator , AMM 27-54-49-000-008 and AMM 27-54-49-400-005.
(a) If the fault continues, do step (5).
(5) If the operational test is OK and the flap surfaces are aligned, but an alignment fault message is shown on the original Post Flight Report, do step (6).
NOTE: When an alignment fault occurs, the flaps on the related wing do not move together correctly. When this fault occurs, the interconnecting strut senses the asymmetry. If the flaps are apparently aligned correctly, but an alignment fault has occurred, then it is possible that the interconnecting strut or the flap rigging is out of adjustment.
(6) Do the adjustment of the interconnecting strut , AMM 27-51-44-820-001. (a) If the fault continues, do step (7).
(7) Do the check of the flap drive system, AMM 27-54-00-820-001.
(a) Do the adjustment of the interconnecting strut again, AMM 27-51-44-820-001.
(b) If the fault continues, do step (8).
(8) Do a check of the flap transmission assembly , AMM 27-54-00-200-001.
(a) From the check of the transmission assembly:
- if the transmission assembly shows backlash, do step (9)
- if the transmission assembly is OK, do the operational test of the flap system, AMM 27-54-00-710-001.
(10) Do the operational test of the flap system, AMM 27-54-00-710-001.