Fuel - Tank Venting, ACT 1 Overpressure Protector 170QM1 Broken

TASK 28-12-00-810-807-A
Fuel - Tank Venting, ACT 1 Overpressure Protector 170QM1 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 ACT pressurized air supply is above the safe limit
the refuel supply pressure is above the safe limit
VALVE-PRESSURE REDUCING, ACT1 [171QM]
VALVE-PRESSURE HOLDING, ACT1 [191QM1]
PROTECTOR-OVERPRESSURE, ACT1 [170QM1]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 28-28-00-810-804-A	Fuel - ACT Automatic Transfer Failure
TSM TASK 28-28-00-810-804-A-01	Fuel - ACT Automatic Transfer Failure (802VU ACT Relay Testbox)
TSM TASK 28-28-00-810-839-A	Fuel - ACT Auto Transfer System - Pressurization Fault
TSM TASK 28-28-00-810-839-A-01	Fuel - ACT Auto Transfer System - Pressurization Fault (802VU ACT Relay Testbox)
AMM 28-12-00-00-
AMM 28-12-00-200-001	Inspection of the Tank Venting System
AMM 28-12-55-000-001	Removal of the ACT Overpressure Protector (170QM)
AMM 28-12-55-400-001	Installation of the ACT Overpressure Protector (170QM)
AMM 28-28-00-710-016	Operational Test of the ACT Pressure Holding Valves (191QM)
AMM 28-28-00-720-001	Functional Test of the ACT Pressure Reducing Valve
AMM 28-28-42-000-001	Removal of the ACT Pressure Reducing Valve
AMM 28-28-42-400-001	Installation of the ACT Pressure Reducing Valve
AMM 28-28-48-000-001	Removal of the ACT Pressure Holding Valve
AMM 28-28-48-400-001	Installation of the ACT Pressure Holding Valve

3. Fault Confirmation
Subtask 28-12-00-710-056-A ** ON A/C NOT FOR ALL

A. Test

NOTE: The function of the overpressure protector 170QM1 is to protect the ACT 1 structure from possible damage.
The operation of the overpressure protector 170QM1 will safely release the (unwanted) pressure as follows:

first to the center tank through the related vent pipe
and then to the atmosphere through the center tank ventilation system installed in the left wing.

The defects that follow (and/or) can cause the overpressure protector 170QM1 to break/operate:

the ACT pressurized air supply is above the safe limit during auto transfer
the refuel supply pressure is above the safe limit during refuel
the ACT 1 internal vent-pipe is blocked.

(1) Do a visual inspection of the overpressure protector 170QM1 AMM 28-12-00-200-001.
(a) If the overpressure protector 170QM1:

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 170QM1 is included as a Possible Cause in the related TSM procedure, ACT Automatic Transfer Failure (Ref. TSM TASK 28-28-00-810-804).

The TSM procedure ACT Auto Transfer System - Pressurization Fault (Ref. TSM TASK 28-28-00-810-839) is also related.

4. Fault Isolation
Subtask 28-12-00-810-056-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 170QM1 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 ACT 1 and its related vent pipe 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 the Functional Test of the ACT Pressure Reducing Valve 171QM AMM 28-28-00-720-001.
(a) If the test pressure is:

as specified, do step (4)
not as specified, do step (3)(b).

(b) Replace the VALVE-PRESSURE REDUCING, ACT1 [171QM] AMM 28-28-42-000-001 and AMM 28-28-42-400-001.
(c) Do step (3) again.
(4) If the ACT has a VALVE-PRESSURE HOLDING, ACT1 [191QM1] installed, do an operational test of it AMM 28-28-00-710-016. Replace, if necessary, AMM 28-28-48-000-001 and AMM 28-28-48-400-001.
(5) Do a check of the ACT 1 vent-pipe between its open end (located below the inward pressure relief valve 172QM1) and the vent valve 167QM1.
(a) Make sure that there is no blockage of the pipe.
(b) Repair or replace all the unserviceable sections of the vent-pipe.
(6) Replace the PROTECTOR-OVERPRESSURE, ACT1 [170QM1] AMM 28-12-55-000-001 and AMM 28-12-55-400-001.
(7) If, when all the tests and inspections are complete:
(a) The cause(s) of the operation (broken/damaged) of the overpressure protector 170QM1 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 170QM1 is found and all the unserviceable 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 04:39:44 UTC