Fuel - Tank Venting, L(R) Surge Tank Overpressure Protector 46QM(47QM) Broken

TASK 28-12-00-810-803-A
Fuel - Tank Venting, L(R) Surge Tank Overpressure Protector 46QM(47QM) Broken

WARNING: OBEY THE FUEL SAFETY PROCEDURES.

1. Possible Causes

intake Assy, NACA vent
PROTECTOR-FUEL VENT, L NACA INTAKE [48QM]
PROTECTOR-FUEL VENT, R NACA INTAKE [49QM]
surge-tank vent-duct between Ribs 23 and 24.
PROTECTOR-OVERPRESSURE, L VENT SURGE TK [46QM]
PROTECTOR-OVERPRESSURE, R VENT SURGE TK [47QM]
PROTECTOR-FUEL VENT, L [194QM]
PROTECTOR-FUEL VENT, R [195QM]

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 28-12-41-000-001	Removal of the Overpressure Protector
AIPC 28124103
AMM 28-12-41-200-003	Inspection of the Overpressure Protector
AMM 28-12-41-400-001	Installation of the Overpressure Protector
AMM 28-12-47-000-001	Removal of the NACA Vent Intake
AMM 28-12-47-400-001	Installation of the NACA Vent Intake

3. Fault Confirmation
Subtask 28-12-00-710-052-A

A. Test

NOTE: The function of the overpressure protector 46QM(47QM) is to protect the left(right) wing surge-tank structure from possible damage.
The operation of the overpressure protector 46QM(47QM) will safely release the (unwanted) pressure directly to the atmosphere.
The defects that follow (and/or) can cause the overpressure protector 46QM(47QM) break/operate:

the surge tank vent duct is blocked
the surge tank flame arrestor is blocked
the surge tank NACA intake is blocked.

A blockage as given above/before can cause the overpressure protector to break/operate because the normal ventilation path was not able to release the unwanted pressure (quickly or sufficiently) safely to the atmosphere.

(1) Do the Inspection of the Overpressure Protector 46QM(47QM) AMM 28-12-41-200-003.
(a) If the overpressure protector 46QM(47QM):

and the related items are as specified, no more troubleshooting work steps are necessary
safety disc has operated (is broken or damaged), and/or the related items are not as specified (example, corroded, wire mesh damaged), do Para. 4.A.

NOTE: The overpressure protector 46QM(47QM) is only included as a Possible Cause in this TSM procedure.

4. Fault Isolation
Subtask 28-12-00-810-052-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 46QM(47QM) 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 an Inspection of the Tank Venting System items that follow AMM 28-12-00-200-001:
(a) The intake Assy, NACA vent.
Replace, if necessary, AMM 28-12-47-000-001 and AMM 28-12-47-400-001.

NOTE: The intake Assy, NACA vent includes the PROTECTOR-FUEL VENT, L NACA INTAKE [48QM] ( PROTECTOR-FUEL VENT, R NACA INTAKE [49QM] ) (flame arrestor).

(b) The surge-tank vent-duct between Ribs 23 and 24.
Replace, if necessary, all sections that are unserviceable (example, damaged or blocked).
(3) Replace the PROTECTOR-OVERPRESSURE, L VENT SURGE TK [46QM] ( PROTECTOR-OVERPRESSURE, R VENT SURGE TK [47QM] ) AMM 28-12-41-000-001 and AMM 28-12-41-400-001.

NOTE: On-aircraft repair of the Protector-Tank, Overpressure (P/N L95F100-603) AIPC 28124103 is not permitted. The complete LRU installed on the panel 550CB(650CB) must be replaced.

(4) If, when all the tests and inspections are complete:
(a) The cause(s) of the operation (broken/damaged) of the overpressure protector 46QM(47QM) 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 46QM(47QM) 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.

Subtask 28-12-00-810-052-B ** ON A/C NOT FOR ALL