W DOC AIRBUS | TSM A320F

Flap System Asymmetry Fault

TASK 27-51-00-810-819-A
Flap System Asymmetry Fault

1. Possible Causes
  • flap transmission assembly
  • POSITION PICK OFF UNIT [29CV]
  • POSITION PICK OFF UNIT [30CV]
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
AMM 27-50-00-480-802
Installation/Removal of the Check Pin at Track 1
AMM 27-50-00-866-012
Manual Retraction of the Flaps
AMM 27-50-00-869-006
Reset of the Wing Tip Brake (WTB) of the Flap System on the Ground
AMM 27-51-00-820-001
Manual Adjustment of the Position Pick-Off Units
AMM 27-51-18-000-001
Removal of the Asymmetry-Position Pick-Off Unit
AMM 27-51-18-400-001
Installation of the Asymmetry-Position Pick-Off Unit
AMM 27-54-00-200-001
Detailed Visual Inspection of the Transmission Assembly
AMM 27-54-00-710-001
Operational Test of the Flap System
3. Fault Confirmation
Subtask 27-51-00-730-050-A
A. Procedure
   (1) Set the MENU MODE and set SFCC 1 or SFCC 2.
     (a) Go to the submenu SYSTEM DATA FLAP.
     (b) Press the line key 1L to set the PPU page.
NOTE: The SFCC transmits the LH and RH APPU DATA page(s) to the CFDS.
Every 5 seconds the data of the APPU DATA page(s) will be refreshed.
     (c) In the TSM:
Refer to page block 301 TABLE 3. The LH APPU and RH APPU synchro angles are shown as a decimal value.
NOTE: A difference of more than 5.2 deg. gives an ASYMMETRY fault message.
     (d) If there is this difference between the LH and RH APPU values, do the fault isolation.
4. Fault Isolation
Subtask 27-51-00-810-069-A
A. Procedure
   (1) Refer to the PPU DATA to find the defective wing (refer to Fault Confirmation):
The APPU DATA that is incremented from the FPPU and other APPU by more than 5.2 deg. shows the defective wing.
   (2) Do the reset of the wing tip brakes AMM 27-50-00-869-006.
   (3) Do the detailed visual inspection of the flap transmission assembly , AMM 27-54-00-200-001.
     (a) During this visual inspection:
  • Examine the possible flap transmission shaft disconnection (rupture, missing flange bolts etc.) of the defective wing.
     (b) Repair or correct any failure found (Ref. AMM chap. 27).
   (4) If the fault continues, do a check of the APPU zero datum mark of the defective wing,
AMM 27-51-00-820-001.
     (a) If the zero datum mark is not aligned, remove the related APPU: POSITION PICK OFF UNIT [29CV] or POSITION PICK OFF UNIT [30CV] , AMM 27-51-18-000-001:
  • Visually examine the APPU/flap actuator mounting interface.
    Repair or correct any failure found.
  • Visually examine the APPU for signs of water through the sight glass and the input shaft for visible dent.
    If necessary replace the APPU, AMM 27-51-18-000-001 and AMM 27-51-18-400-001.
     (b) If the APPU is found in good condition, do the steps that follow:
       1 With the APPU not installed on the defective wing:
NOTE: In this condition it is not necessary to record the PPU angle values before manual extension.
       2 Do the manual adjustment of the APPU, AMM 27-51-00-820-001.
  • If you feel frictions while turning the APPU input shaft,
    install a new APPU, AMM 27-51-18-400-001.
  • If you feel no friction, install the old APPU again.
   (5) Before the operational test:
     (a) Do the operational test of the flap system, AMM 27-54-00-710-001.
   (6) Get access to the SYSTEM STATUS FLAP page and make sure that NO FAULTS is shown.
[Rev.8 from Aug 2018] 2026.04.04 04:27:38 UTC
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