Fuel - Tank Venting, L(R) Wing Tank (Inner Cell) Overpressure Protector Broken (Not Coded With FIN) Installed on the Access Panel 540HB(640HB), Type 25A

TASK 28-12-00-810-805-A
Fuel - Tank Venting, L(R) Wing Tank (Inner Cell) Overpressure Protector Broken (Not Coded With FIN) Installed on the Access Panel 540HB(640HB), Type 25A

WARNING: OBEY THE FUEL SAFETY PROCEDURES.

CAUTION: DO NOT LET THE REFUEL PRESSURE BE MORE THAN THE MAXIMUM SAFE PRESSURE OF 50psi (3.45bar).

1. Possible Causes

the refuel supply pressure is above the safe limit
VALVE-REFUEL, L WING TK [7QU]
VALVE-REFUEL, R WING TK [8QU]
VALVE-FLOAT VENT, L WING TK INR [16QM]
VALVE-FLOAT VENT, R WING TK INR [17QM]
L(R) wing-tank vent-pipe/duct
L(R) wing-tank (inner-cell) overpressure protector

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 28-12-00-00-
AMM 28-12-00-200-001	Inspection of the Tank Venting System
AMM 28-12-43-000-002	Removal of the Vent Float-Valve
AMM 28-12-43-400-002	Installation of the Vent Float-Valve
AMM 28-12-46-000-001	Removal of the Overpressure-Protector Outlet
AMM 28-12-46-200-001	Inspection of the Wing-Tank Overpressure Protector Outlet
AMM 28-12-46-400-001	Installation of the Overpressure-Protector Outlet
AMM 28-25-00-710-003	Operational Test of the Refuel System
AMM 28-25-51-000-001	Removal of the Refuel Valve
AMM 28-25-51-400-001	Installation of the Refuel Valve

3. Fault Confirmation
Subtask 28-12-00-710-054-A ** ON A/C NOT FOR ALL

A. Test

NOTE: The function of the overpressure protector (located at the inner-cell access-panel/door (type 25A) between Ribs 13 and 14) is to protect the L(R) wing-tank inner-cell structure from possible damage.
The operation of this overpressure protector will safely release the (unwanted) pressure to the atmosphere.
The defects that follow (and/or) can cause the over pressure protector to break/operate:

the refuel supply pressure is above the safe limit
the L(R) wing-tank vent pipe/duct is blocked
the float vent valve 16QM(17QM) cannot open (or sufficiently) to release the (unwanted) pressure
the related L(R) wing-tank refuel valve 7QU(8QU) does not close correctly.

(1) Do the Inspection of the Wing-Tank Overpressure Protector Outlet AMM 28-12-46-200-001.
(a) If the overpressure protector outlet:

and the related items are as specified, no more troubleshooting work steps are necessary
is found to be serviceable but the related items are not as specified (example, corroded, wire mesh damaged), make them good before you do the close-up
safety disc has operated (is broken or damaged), do Para. 4.A.

NOTE: The overpressure protector outlet is only included as a Possible Cause in this TSM procedure.

4. Fault Isolation
Subtask 28-12-00-810-054-A ** ON A/C NOT FOR ALL

A. Procedure

NOTE: Read all of the steps in this paragraph before you start work.
The order in which the work steps are done is best decided by the maintenance staff together with:

other malfunction indications
the fuel configuration
the aircraft location.

(1) If the (frangible) overpressure protector outlet has operated (is broken), it is important to do all the steps that follow to find what caused it to break.

NOTE: The reasons why a burst disc can break are as follows:

a defective/unserviceable disk (non standard)
that breaks below the (its) correct operating pressure
a serviceable disk that operated because the pressure difference between the wing-tank (inner-cell) and the outside atmospheric pressure was more than the correct safe operating pressure AMM 28-12-00-00-.

(2) Do a check of the applicable fuel tanker or fuel hydrant hose end pressure.
(a) If the fuel pressure is more than 50psi (3.45bar):

change the fuel pressure if possible or
get another source of fuel supplied at the correct pressure.

NOTE: If the fuel tanker or fuel hydrant hose end pressure is more than the maximum safe pressure it can cause:

a refuel valve that has been commanded to shut, to stay open
a overpressure protector (burst disc) to operate
damage to the refuel gallery.

(3) Do a check of the related L(R) wing-tank refuel valve 7QU(8QU) as follows:
(a) Remove the applicable refuel valve 7QU(8QU) AMM 28-25-51-000-001.
(b) Do a visual inspection of the refuel valve 7QU(8QU), valve position.
1 If the valve is (stays) in the open position, replace the VALVE-REFUEL, L WING TK [7QU] ( VALVE-REFUEL, R WING TK [8QU] ) AMM 28-25-51-000-001 and AMM 28-25-51-400-001.
2 If the valve is in the closed position or if the valve is replaced in step 1_, do an operational test of the applicable wing-tank refuel valve 70QU(8QU) (to see if it can open and close) AMM 28-25-00-710-003.
3 If there is any malfunction of the refuel valve 7QU(8QU) and/or related sub-systems, refer to the Troubleshooting Fault Symptoms List, for the related Task number, and do the necessary troubleshooting.
(4) Do an Inspection of the Tank Venting System items that follow AMM 28-12-00-200-001:
(a) The VALVE-FLOAT VENT, L WING TK INR [16QM] ( VALVE-FLOAT VENT, R WING TK INR [17QM] ) and replace, if necessary, AMM 28-12-43-000-002 and AMM 28-12-43-400-002.
(b) The L(R) wing-tank vent-pipe/duct and replace, if necessary, all sections that are unserviceable (example, damaged or blocked).
(5) Replace the L(R) wing-tank (inner-cell) overpressure protector AMM 28-12-46-000-001 and AMM 28-12-46-400-001.
(6) If, when all the tests and inspections are complete:
(a) The cause(s) of the operation (broken/damaged) of the overpressure protector installed on access panel 540HB(640HB) has(have) been found (and all the unserviceable LRUs have been replaced):
1 Refuel the aircraft and return it to service.
(b) If no cause of the operation of the overpressure protector 540HB(640HB) is found and all the unserviceable have been replaced:
1 Put the aircraft back into operation.
2 Send the damaged overpressure protector 540HB(640HB) to the vendor.
3 If the fault continues, refer the problem to AIRBUS.

[Rev.8 from Aug 2018] 2026.04.04 04:28:28 UTC