Fuel - Tank Venting, Center Tank Overpressure Protector 96QM Broken

TASK 28-12-00-810-802-A
Fuel - Tank Venting, Center Tank Overpressure Protector 96QM Broken

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, CTR TK [10QU]
center-tank vent-pipe
VALVE-PRESSURE RELIEF, CTR TK [97QM]
PROTECTOR-OVERPRESSURE, CTR TK [96QM]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 28-12-00-810-801-A	Fuel - Unwanted Transfer From The Left Wing Tank To The Center Tank At Any Time
AMM 28-12-00-00-
AMM 28-12-00-200-001	Inspection of the Tank Venting System
AMM 28-12-41-000-003	Removal of the Overpressure Protector
AMM 28-12-41-200-002	Inspection of the Overpressure Protector
AMM 28-12-41-400-003	Installation of the Overpressure Protector
AMM 28-25-00-710-003	Operational Test of the Refuel System
AMM 28-25-45-000-001	Removal of the Center-Tank Pressure-Relief Valve
AMM 28-25-45-400-001	Installation of the Center-Tank Pressure-Relief Valve
AMM 28-25-51-000-002	Removal of the Refuel Valve
AMM 28-25-51-400-002	Installation of the Refuel Valve

3. Fault Confirmation
Subtask 28-12-00-710-051-B

A. Test

NOTE: The function of the overpressure protector 96QM is to protect the center tank structure from possible damage.
The operation of the overpressure protector 96QM will safely release the (unwanted) pressure to the atmosphere through the left wing tank ventilation system.
The defects that follow (and/or) can cause the overpressure protector 96QM to break/operate:

the center tank vent pipe is blocked
the refuel supply pressure is above the safe limit
the pressure relief valve 97QM cannot open (or cannot open quickly or sufficiently) to release the (unwanted) pressure safely to the atmosphere through the right wing tank ventilation system.

(1) Do the Inspection of the Overpressure Protector 96QM AMM 28-12-41-200-002.
(a) If the overpressure protector 96QM:

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 96QM is included as a Possible Cause in the related TSM procedure, Unwanted Transfer From The Left Wing Tank To The Center Tank At Any Time (Ref. TSM TASK 28-12-00-810-801).

4. Fault Isolation
Subtask 28-12-00-810-051-B

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 96QM 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 center tank and the adjacent left wing tank 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 center tank refuel valve 10QU as follows:
(a) Remove the center tank refuel valve 10QU AMM 28-25-51-000-002.
(b) Do a visual inspection of the refuel valve 10QU, valve position.
1 If the valve is (stays) in the open position, replace the VALVE-REFUEL, CTR TK [10QU] AMM 28-25-51-000-002 and AMM 28-25-51-400-002.
2 If the valve is in the closed position (or if the valve is replaced in step 1_) do an operational test of the center tank refuel valve 10QU (to see if it can open and close) AMM 28-25-00-710-003.
3 If there is any malfunction of the refuel valve 10QU (and/or related sub-systems) refer to the Troubleshooting Fault Symptoms List, for the related Task number. Do the necessary troubleshooting.
(4) Do an Inspection of the Tank Venting System AMM 28-12-00-200-001 (the center-tank vent-pipe ). Replace, if necessary, all sections that are unserviceable (example, damaged or blocked).
(5) Do a check of the pressure relief valve 97QM as follows:
(a) Get access to the pressure relief valve 97QM AMM 28-25-45-000-001.
(b) Do a visual check of the pressure relief valve 97QM to see if it:

has become blocked
can open (functionally operate) with a full and free movement.

(c) If necessary, remove any blockage/obstruction or replace the VALVE-PRESSURE RELIEF, CTR TK [97QM] AMM 28-25-45-000-001 and AMM 28-25-45-400-001.
(6) Replace the PROTECTOR-OVERPRESSURE, CTR TK [96QM] AMM 28-12-41-000-003 and AMM 28-12-41-400-003.
(7) If, when all the tests and inspections are complete:

(a) The cause(s) of the operation (broken/damaged) of the overpressure protector 96QM 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 over pressure protector 96QM is found and all the unserviceable LRUs have been replaced:
1 Put the aircraft back into operation.
2 Send the damaged overpressure protector to the vendor.
3 If the fault continues, refer the problem to AIRBUS.

[Rev.8 from Aug 2018] 2026.04.04 04:28:27 UTC