DOC AIRBUS | TSM A320FWTB/POB Test Performed Unsuccessfully or Test Aborted
TASK 27-51-00-810-855-A
WTB/POB Test Performed Unsuccessfully or Test Aborted
1. Possible Causes
A. Referenced Information
3. Fault Confirmation
Subtask 27-51-00-710-082-A
Subtask 27-51-00-810-107-A
[Rev.8 from Aug 2018]
2026.04.04 04:27:40 UTC
WTB/POB Test Performed Unsuccessfully or Test Aborted
1. Possible Causes
- WING TIP BRAKE [33CV]
- WING TIP BRAKE [34CV]
- POB of the PCU
HYD LEAK MEASUREMENT VALVES G/B/Y - lever movement
- low hydraulic pressure
A. Referenced Information
| REFERENCE | DESIGNATION |
|---|---|
| AMM 27-50-00-869-006 | Reset of the Wing Tip Brake (WTB) of the Flap System on the Ground |
| AMM 27-51-00-710-001 | Operational Test of the Wing Tip Brake and the Pressure Off Brake |
| AMM 27-51-00-740-002 | BITE Test of the Slat and Flap Control Computers (Flap System) |
| AMM 27-51-51-000-001 | Removal of the Flap Wing-Tip Brake |
| AMM 27-51-51-400-001 | Installation of the Flap Wing-Tip Brake |
| AMM 27-54-52-000-001 | Removal of the Pressure-Off Brake of the Flap Power Control Unit |
| AMM 27-54-52-400-001 | Installation of the Pressure-Off Brake of the Flap Power Control Unit |
Subtask 27-51-00-710-082-A
A. Test
(1) Do the WTB/POB test AMM 27-51-00-710-001:
4. Fault Isolation(1) Do the WTB/POB test AMM 27-51-00-710-001:
- If the information PERFORMED UNSUCCESSFULLY or TEST ABORTED is shown, go to the Para. Fault Isolation.
- If the test is PERFORMED (NO FAULTS), no other maintenance action is necessary.
Subtask 27-51-00-810-107-A
A. Procedure
PERFORMED UNSUCCESSFULLY
TEST RESULT (NOT STORED)
LH WTB XXX_________ xxCV
RH WTB XXX_________ xxCV
POB XXX____________ xxCV
(a) If XXX shows FAILURE:
1 Do the BITE test of the related SFCC and make sure that there are no fault messages AMM 27-51-00-740-002.
(b) If XXX shows TEST INVALID:
PERFORMED UNSUCCESSFULLY
TEST RESULT (NOT STORED)
LH WTB TEST INVALID xxCV
RH WTB TEST INVALID xxCV
POB ___TEST INVALID xxCV
REPEAT WTB/POB TEST
WITH HYDRAULIC LEAK
MEASUREMENT VALVES OFF
(a) If TEST INVALID shows at all LRUs:
1 On the overhead panel 50VU, lift the guard and push theHYD LEAK MEASUREMENT VALVES G/B/Y pushbutton switches to the OFF position.
2 Then do the WTB/POB test again AMM 27-51-00-710-001.
(3) If the test is aborted because of a lever movement during the test (the lever must stay in position 3):
Then the MCDU shows:
TEST ABORTED
OPERATOR HAS MOVED LEVER
(a) Move the lever to position 3 and do the WTB/POB test again.
(4) If the test is aborted because of a system failure (then the MCDU shows):
TEST ABORTED
SYSTEM FAILURE
XXX
<RESTART TEST
(a) If XXX shows LOW HYDRAULIC PRESSURE:
2 Then do the WTB/POB test again (push 5L to restart the test).
(b) If XXX shows WTB POWER OFF:
1 Make sure that the WTBs are energized correctly during the WTB/POB test.
2 Do the BITE test of the related SFCC to get the information of the current status of the flap system AMM 27-51-00-740-002.
3 After this BITE test:
(5) If the test is aborted because of a system fault and maintenance action is necessary before the restart of the test (then the MCDU shows):
TEST ABORTED
SYSTEM FAILURE
XX
WTB SET
___!!WARNING!!___
SYSTEM MAY STILL BE
_____TWISTED___
1 Do the reset of the WTB AMM 27-50-00-869-006.
2 Do the BITE test of the related SFCC again and make sure that there are no fault messages AMM 27-51-00-740-002.
(b) If XX shows LOW HYDRAULIC PRESSURE:
1 Do the WTB/POB test again and make sure that the Green, Yellow and Blue hydraulic systems have a pressure of 3000 psi (207 bar).
Refer to the information concerning the pressurization in the WTB/POB test procedure in the AMM AMM 27-51-00-710-001.
(c) If XX shows PPU FAULT or VPS FAULT or WTB CONTINUITY or POSITION FAULT:
1 Do the BITE test of the related SFCC to get the information of the current status of the flap system AMM 27-51-00-740-002.
2 After this BITE test:
NOTE: General Information:
Each time after a 'SFCC BITE TEST' because of a maintenance action (replacement of a LRU/repairing of wiring) it is necessary to go from the off-line mode (SFCC MENU mode) to the on-line mode (SFCC NORMAL mode).
The WTB/POB test will not operate if a BITE test was completed before without going from the off-line mode to the on-line mode.
Subsequently a 'CORRUPTED RAM -RETURN ONLINE' or a 'PIN PROG FAULT' will be shown.
(1) If the WTB/POB test was completed but there was a failure of the WTB or POB (then the MCDU shows): Each time after a 'SFCC BITE TEST' because of a maintenance action (replacement of a LRU/repairing of wiring) it is necessary to go from the off-line mode (SFCC MENU mode) to the on-line mode (SFCC NORMAL mode).
The WTB/POB test will not operate if a BITE test was completed before without going from the off-line mode to the on-line mode.
Subsequently a 'CORRUPTED RAM -RETURN ONLINE' or a 'PIN PROG FAULT' will be shown.
PERFORMED UNSUCCESSFULLY
TEST RESULT (NOT STORED)
LH WTB XXX_________ xxCV
RH WTB XXX_________ xxCV
POB XXX____________ xxCV
(a) If XXX shows FAILURE:
- Replace the related WTB WING TIP BRAKE [33CV] or WING TIP BRAKE [34CV] ,
AMM 27-51-51-000-001 and AMM 27-51-51-400-001
- Or replace the POB of the PCU ,
AMM 27-54-52-000-001 and AMM 27-54-52-400-001.
1 Do the BITE test of the related SFCC and make sure that there are no fault messages AMM 27-51-00-740-002.
NOTE: Refer to the NOTE (General Information) which is given above.
2 Do the WTB/POB test again AMM 27-51-00-710-001. (b) If XXX shows TEST INVALID:
- The hydraulic pressure was not sufficient to do the operational test of the related WTB and/or POB:
Do the WTB/POB test again and make sure that the Green, Yellow and Blue hydraulic systems have a pressure of 3000 psi (207 bar).
Refer to the information concerning the pressurization in the WTB/POB test procedure in the AMM AMM 27-51-00-710-001.
PERFORMED UNSUCCESSFULLY
TEST RESULT (NOT STORED)
LH WTB TEST INVALID xxCV
RH WTB TEST INVALID xxCV
POB ___TEST INVALID xxCV
REPEAT WTB/POB TEST
WITH HYDRAULIC LEAK
MEASUREMENT VALVES OFF
(a) If TEST INVALID shows at all LRUs:
1 On the overhead panel 50VU, lift the guard and push the
2 Then do the WTB/POB test again AMM 27-51-00-710-001.
(3) If the test is aborted because of a lever movement during the test (the lever must stay in position 3):
Then the MCDU shows:
TEST ABORTED
OPERATOR HAS MOVED LEVER
(a) Move the lever to position 3 and do the WTB/POB test again.
(4) If the test is aborted because of a system failure (then the MCDU shows):
TEST ABORTED
SYSTEM FAILURE
XXX
<RESTART TEST
(a) If XXX shows LOW HYDRAULIC PRESSURE:
- The WTB/POB test was not operated because of low hydraulic pressure :
2 Then do the WTB/POB test again (push 5L to restart the test).
(b) If XXX shows WTB POWER OFF:
1 Make sure that the WTBs are energized correctly during the WTB/POB test.
2 Do the BITE test of the related SFCC to get the information of the current status of the flap system AMM 27-51-00-740-002.
3 After this BITE test:
- If the BITE test result is positive (the page shows FLAP SFCC TEST NO FAULTS), do the WTB/POB test again.
NOTE: Refer to the NOTE (General Information) which is given above.
- If the BITE test result is negative (the page shows FLAP SFCC TEST PERFORMED WITH FAULTS):
Refer to this fault message and do the related trouble shooting procedure(s). - After the replacement/repair of the defective LRU/wiring:
Do the BITE test of the related SFCC again and make sure that there are no fault messages AMM 27-51-00-740-002.
NOTE: Refer to the NOTE (General Information) which is given above.
4 Do the WTB/POB test again AMM 27-51-00-710-001. (5) If the test is aborted because of a system fault and maintenance action is necessary before the restart of the test (then the MCDU shows):
TEST ABORTED
SYSTEM FAILURE
XX
WTB SET
___!!WARNING!!___
SYSTEM MAY STILL BE
_____TWISTED___
NOTE: In this case the WTB was set during the WTB/POB test as a result of a system fault.
The indication '!!WARNING!! SYSTEM MAY STILL BE TWISTED' is shown because of WTB application.
(a) If the WTB was set: The indication '!!WARNING!! SYSTEM MAY STILL BE TWISTED' is shown because of WTB application.
1 Do the reset of the WTB AMM 27-50-00-869-006.
2 Do the BITE test of the related SFCC again and make sure that there are no fault messages AMM 27-51-00-740-002.
NOTE: Refer to the NOTE (General Information) which is given above.
3 Do the WTB/POB test again AMM 27-51-00-710-001. (b) If XX shows LOW HYDRAULIC PRESSURE:
1 Do the WTB/POB test again and make sure that the Green, Yellow and Blue hydraulic systems have a pressure of 3000 psi (207 bar).
Refer to the information concerning the pressurization in the WTB/POB test procedure in the AMM AMM 27-51-00-710-001.
(c) If XX shows PPU FAULT or VPS FAULT or WTB CONTINUITY or POSITION FAULT:
1 Do the BITE test of the related SFCC to get the information of the current status of the flap system AMM 27-51-00-740-002.
2 After this BITE test:
- If the BITE test result is negative (the page shows FLAP SFCC TEST PERFORMED WITH FAULTS):
Refer to this fault message and do the related trouble shooting procedure(s). - After the replacement/repair of the defective LRU/wiring:
- Do the BITE test of the related SFCC again and make sure that there are no fault messages AMM 27-51-00-740-002.
NOTE: Refer to the NOTE (General Information) which is given above.
3 Do the WTB/POB test again AMM 27-51-00-710-001.