Leak Test of the Pressure Holding Valve (PHV)(s)

TASK 28-28-49-720-001-A
Leak Test of the Pressure Holding Valve (PHV)(s)

WARNING: OBEY THE FUEL SAFETY PROCEDURES.

WARNING: BEFORE YOU DO WORK IN OR NEAR A FUEL TANK, MAKE SURE THAT YOU OBEY ALL THE SAFETY PROCEDURES. THIS WILL PREVENT INJURY TO PERSONS AND/OR DAMAGE TO THE AIRCRAFT.

WARNING: PUT THE SAFETY DEVICES AND THE WARNING NOTICES IN POSITION BEFORE YOU START A TASK ON OR NEAR:

THE FLIGHT CONTROLS
THE FLIGHT CONTROL SURFACES
THE LANDING GEAR AND THE RELATED DOORS
COMPONENTS THAT MOVE.

MOVEMENT OF COMPONENTS CAN KILL OR CAUSE INJURY TO PERSONS AND/OR CAN CAUSE DAMAGE TO THE EQUIPMENT.

WARNING: MAKE SURE THAT THE GROUND SAFETY-LOCKS ARE IN POSITION ON THE LANDING GEAR. THIS WILL PREVENT UNWANTED MOVEMENT OF THE LANDING GEAR, AND THUS POSSIBLE INJURY TO PERSONS AND DAMAGE TO THE AIRCRAFT AND/OR EQUIPMENT.

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

CAUTION: MAKE SURE THAT THE TEST EQUIPMENT INCLUDES A SAFETY SYSTEM TO PREVENT TOO MUCH PRESSURE. TOO MUCH PRESSURE CAN CAUSE DAMAGE TO THE AIRCRAFT.

ZONE: 140
ZONE: 150
ZONE: 160
FIN: 241QM ** ON A/C NOT FOR ALL
FIN: 242QM ** ON A/C NOT FOR ALL
FIN: 243QM ** ON A/C NOT FOR ALL

1. Reason for the Job

NOTE: For the New Engine Option (NEO) aircraft with an Additional Center Tank (ACT) installed in the forward cargo compartment, the term ACT FWD can also be described as ACT 4.1.

NOTE: If ACT1 (or ACT AFT1) is installed and ACT4 (or ACT FWD) is not installed, do the test in Paragraph 4.A.
If ACT1 (or ACT AFT1) and ACT4 (or ACT FWD) are both installed, do the test in Paragraph 4.B.

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	2	ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE
No specific	1	ADAPTER 0,75 IN (19,05 MM) - SQUARE DRIVE
No specific	1	GAGE 5 BAR (75 PSI) - PRESSURE
No specific	1	GROUND PRESSURE GENERATOR - 0 TO 2 BAR (0 TO 30 PSI)
No specific	AR	SAFETY BARRIER(S)
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 0.06 and 0.055 m.daN (5.31 and 4.87 lbf.in )

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.14CBB1)	Testing Medium-Leak Detection Bubbles -
(Material No.14SBA1)	Textile-Lint free Cotton -

C. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
140	CENTER WING
150	AFT CARGO COMPARTMENT FWD PRESS BULKHEAD TO AFT BULKHEAD OF AFT CARGO COMPARTMENT
160	BULK CARGO COMPARTMENT AFT BULKHEAD OF AFT CARGO COMPARTMENT TO AFT BULKHEAD OF BULK CARGO COMPARTMENT
148AZ, 744, 826

D. Referenced Information

REFERENCE	DESIGNATION
TASK 12-11-28-650-004-A	Pressure Refuel with Manual Control
TASK 24-41-00-861-002-A	Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01	Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 24-41-00-862-002-A	De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01	De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02	De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
TASK 28-00-00-910-001-A	Fuel Safety Procedures
TASK 28-10-00-910-002-A	Access to the Fuel Tanks and the Work Areas
TASK 28-10-00-910-003-A	Safety Procedures When You Do Work in a Dry Fuel Tank
TASK 28-25-00-650-001-A	Pressure Defuel
TASK 28-25-00-869-001-A	Fuel Transfer
TASK 32-00-00-481-001-A	Installation of the Safety Devices on the Landing Gears
TASK 32-12-00-010-001-A	Open the Main Gear Doors for Access
TASK 32-12-00-410-001-A	Close the Main Gear Doors after Access
TASK 52-30-00-860-001-A	Open the FWD or Aft Cargo-Compartment Door with the Yellow Electric Pump
TASK 52-30-00-860-002-A	Close the FWD or Aft Cargo-Compartment Door with the Yellow Electric Pump
TASK 57-17-11-000-001-B	Removal of Access Cover 148AZ or/and the ACT-Equipment Support Door
TASK 57-17-11-400-001-B	Installation of Access Cover 148AZ or/and the ACT-Equipment Support-Door
ACT Vent System - Schematic ** ON A/C NOT FOR ALL
ACT Vent System - Connection of GPG
ACT Vent System - Schematic ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 28-28-49-941-051-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) Obey the fuel safety precautions (Ref. AMM TASK 28-00-00-910-001).
(2) Make sure that the ground safety locks are installed on the landing gear (Ref. AMM TASK 32-00-00-481-001).
(3) Put the WARNING NOTICE(S) on the panels that follow to tell persons not to operate the refuel/defuel system:

Refuel/Defuel panels 800VU and 801VU
Fuel control panel 40VU
Additional Center Tank (ACT) control panel 28VU.

(4) Put the WARNING NOTICE(S) in position to tell persons not to operate the MLG doors.
(5) As necessary, use the applicable SAFETY BARRIERS, specified by the operator's instructions and your local regulations.

Subtask 28-28-49-650-052-A ** ON A/C NOT FOR ALL

B. Fuel Configuration
(1) Refuel, defuel or transfer the fuel (Ref. AMM TASK 12-11-28-650-004), (Ref. AMM TASK 28-25-00-650-001) or (Ref. AMM TASK 28-25-00-869-001) to get these fuel levels:

Center tank is empty
ACT(s) is(are) full.

NOTE: The wing tanks can be empty or full. The quantity of fuel in the wing tanks will not have an effect on this procedure.

NOTE: The ACT(s) can be empty of fuel, but it is necessary to pressurize the inner space of the ACT(s).

Subtask 28-28-49-865-053-A ** ON A/C NOT FOR ALL

C. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	FUEL/ACT AIR SOV/MAN/SPLY	64QH	J20
121VU	FUEL/ACT AIR SOV/AUTO/SPLY	63QH	J19
121VU	FUEL/INLET VLV/MOT1/AFT 2	84QH	L29
121VU	FUEL/INLET VLV/MOT1/MAN SPLY/AFT 1	46QH	L28

Subtask 28-28-49-860-051-A ** ON A/C NOT FOR ALL

D. Aircraft Maintenance Configuration
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) On refuel/defuel control panel 801VU:
(a) Make sure that all of the ACT REFUEL VALVE switch(es) is(are) in the NORM and guarded position.
(3) In the cockpit, on ACT fuel control-panel 28VU:
(a) Make sure that the ACT XFR rotary switch is in the OFF position.
(b) Push the ACT XFR MODE SEL pushbutton switch (P/BSW) (the MAN legend comes on).

NOTE: If the circuit breakers are open:

ACT vent valve 234QM in the center tank closes.
Air shutoff valve 233QM and fuel inlet valves 228QM1, 228QM2, 228QM3, 228QM4 and 228QM5 in each ACT stay closed.

Forward ACT vent isolation-valve 232QM is permanently open.

(4) Put the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position at aft cargo-compartment door 826.
(5) Open aft cargo-compartment door 826 (Ref. AMM TASK 52-30-00-860-001).
(6) Put the WARNING NOTICE(S) on the aft cargo loading-system control-panel to tell persons not to use it.

Subtask 28-28-49-860-051-B ** ON A/C NOT FOR ALL

D. Aircraft Maintenance Configuration
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) On refuel/defuel control-panel 801VU:
(a) Make sure that all of the ACT REFUEL VALVE switch(es) is(are) in the NORM and guarded position.
(3) In the cockpit, on ACT control-panel 28VU:
(a) Make sure that the ACT XFR rotary switch is in the OFF position.
(b) Push the ACT XFR MODE SEL pushbutton switch (the MAN legend comes on).

NOTE: If the circuit breakers are open:

ACT vent-valve 234QM in the center tank stays closed.
Air shutoff-valve 233QM and fuel inlet-valves 228QM1 and 228QM2 in each ACT stay closed.

(4) Put the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position at aft cargo-compartment door 826.
(5) Open aft-cargo compartment-door 826 (Ref. AMM TASK 52-30-00-860-001).
(6) Put the WARNING NOTICE(S) on the aft-cargo loading-system control-panel to tell persons not to use the aft-cargo loading-system.

Subtask 28-28-49-865-054-A ** ON A/C NOT FOR ALL

E. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	FUEL/ACT XFR VLV/MOT2	66QH	J18
121VU	FUEL/ACT XFR VLV/MOT1	65QH	J17
121VU	FUEL/ACT VENT VLV/MAN/SPLY	62QH	L21
121VU	FUEL/ACT VENT VLV/AUTO/SPLY	61QH	L20

Subtask 28-28-49-010-051-B ** ON A/C NOT FOR ALL

F. Get Access

ACT Vent System - Connection of GPG ** ON A/C NOT FOR ALL

(1) Open right-hand Main-Landing-Gear (MLG) door 744 (Ref. AMM TASK 32-12-00-010-001).
(2) Make sure that the GROUND LOCK SLEEVE is installed on the right-hand-MLG door actuating-cylinder.
(3) Put the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE below center-tank right-hand access-cover 148AZ.
(4) Remove access cover 148AZ (Ref. AMM TASK 28-10-00-910-002) and (Ref. AMM TASK 57-17-11-000-001).
(5) In the aft cargo compartment:
(a) Set CARGO COMPT LIGHT switch 8LU to the ON position.
(b) Get access to ACT pressurization-system test-connector T2:
1 Loosen the studs (1) and open the access panel (2).

Subtask 28-28-49-480-050-A ** ON A/C NOT FOR ALL

G. Preparation for Test

ACT Vent System - Connection of GPG ** ON A/C NOT FOR ALL

(1) In the aft cargo-compartment at ACT pressurization-system test-connector T2:

Connect a ADAPTER 0,75 IN (19,05 MM) - SQUARE DRIVE
Connect a GAGE 5 BAR (75 PSI) - PRESSURE
Connect a GROUND PRESSURE GENERATOR - 0 TO 2 BAR (0 TO 30 PSI).

4. Procedure
Subtask 28-28-49-790-050-B ** ON A/C NOT FOR ALL

A. Test of the PHV(s)
(1) Obey the safety precautions when you do work in a dry fuel tank (Ref. AMM TASK 28-10-00-910-003).
(2) Do the test that follows to do a check of PHVs 243QM and 242QM.

NOTE: This test is applicable if ACT AFT1 is installed.

ACTION	RESULT
1.At the ground pressure generator: Start the ground pressure generator.	At the vent system: Air goes into the ACT vent line and pressurizes the vent system.
2.On the ground pressure generator: Increase the flow of air until the indication on the pressure gage becomes stable at 345 -0 mbar or +103 mbar (5.00 -0 psi or +1.49 psi).	At the vent system: The ACT vent system is pressurized.
3.On the ground pressure generator: Keep the pressure at 345 -0 mbar or +103 mbar (5.00 -0 psi or +1.49 psi).
4.Inner side of the center tank: Apply Testing Medium-Leak Detection Bubbles - (Material No.14CBB1) to the interface of PHVs 243QM and 242QM and the vent pipe. Examine the vent pipe interface for leaks or sign of bubbles.	Inner side of the center tank: At the vent pipe interface of PHVs 243QM and 242QM: Make sure that there are no leaks.
5.At the ground pressure generator: Stop the ground pressure generator.
6.At the ground pressure generator: Carefully release the pressure.	At the vent system: The ACT vent system is depressurized between test connector T2 and ACT AFT1 inlet-check-valve 231QM1. The ACT vent system is pressurized between ACT AFT1 inlet-check-valve 231QM1 and ACT vent-valve 234QM.
7.Make an entry in the aircraft technical log that you do the test of the PHV (241QM) at the next installation of the ACT FWD.

Subtask 28-28-49-790-050-C ** ON A/C NOT FOR ALL

A. Test of the PHV(s)
(1) Obey the safety precautions when you do work in a dry fuel tank (Ref. AMM TASK 28-10-00-910-003).
(2) Do the test that follows to do a check of PHVs 243QM and 242QM.

NOTE: This test is applicable if ACT AFT1 is installed.

ACTION	RESULT
1.At the ground pressure generator: Start the ground pressure generator.	At the vent system: Air goes into the ACT vent line and pressurizes the vent system.
2.On the ground pressure generator: Increase the flow of air until the indication on the pressure gage becomes stable at 345 -0 mbar or +103 mbar (5.00 -0 psi or +1.49 psi).	At the vent system: Make sure that the ACT vent system is pressurized.
3.On the ground pressure generator: Make sure that the pressure stays at 345 -0 mbar or +103 mbar (5.00 -0 psi or +1.49 psi).
4.Inner side of the center tank: Apply Testing Medium-Leak Detection Bubbles - (Material No.14CBB1) to the interface of PHVs 243QM and 242QM and the vent pipe. Examine the vent pipe interface for leaks or sign of bubbles.	Inner side of the center tank: At the vent pipe interface of PHVs 243QM and 242QM: Make sure that there are no leaks.
5.At the ground pressure generator: Stop the ground pressure generator.
6.At the ground pressure generator: Carefully release the pressure.	At the vent system: Make sure that the ACT vent system is depressurized between test connector T2 and ACT AFT1 inlet-check-valve 231QM1. Make sure that the ACT vent system is pressurized between ACT AFT1 inlet-check-valve 231QM1 and ACT vent-valve 234QM.

Subtask 28-28-49-790-051-B ** ON A/C NOT FOR ALL

B. Test of the PHV(s)
(1) Obey the safety precautions when you do work in a dry fuel tank (Ref. AMM TASK 28-10-00-910-003).
(2) Do the test that follows to do a check of PHVs 243QM, 242QM and 241QM.

NOTE: This test is applicable if ACT AFT1 and the ACT FWD are installed.

ACTION	RESULT
1.At the ground pressure generator: Start the ground pressure generator.	At the vent system: Air goes into the ACT vent line and pressurizes the vent system.
2.On the ground pressure generator: Increase the flow of air until the indication on the pressure gage becomes stable at 345 -0 mbar or +103 mbar (5.00 -0 psi or +1.49 psi).	At the ACT vent system: Make sure that the ACT vent system is pressurized.
3.On the ground pressure generator: Make sure that the pressure stays at 345 -0 mbar or +103 mbar (5.00 -0 psi or +1.49 psi).
4.Inner side of the center tank: Apply Testing Medium-Leak Detection Bubbles - (Material No.14CBB1) to the interface of PHVs 243QM, 242QM and 241QM and the vent pipe. Examine the vent pipe interface for leaks or sign of bubbles.	Inner side of the center tank: At the vent pipe interface of PHVs 243QM, 242QM and 241QM: Make sure that there are no leaks.
5.At the ground pressure generator: Stop the ground pressure generator.
6.At the ground pressure generator: Carefully release the pressure.	At the vent system: Make sure that the ACT vent system is depressurized between test connector T2 and ACT AFT1 inlet-check-valve 231QM1 and ACT FWD inlet-check-valve 231QM4. Make sure that the ACT vent system is pressurized between the ACT AFT1 and ACT FWD inlet-check-valves and ACT vent-valve 234QM4.

5. Close-up
Subtask 28-28-49-080-050-A ** ON A/C NOT FOR ALL

A. Removal of the Test Equipment
(1) At test connector T2:
(a) Disconnect the GPG from the low pressure gage.
(b) Remove the low pressure gage and the adapter from test connector T2.

Subtask 28-28-49-410-052-B ** ON A/C NOT FOR ALL

B. Close Access

ACT Vent System - Connection of GPG ** ON A/C NOT FOR ALL

(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close access to test connector T2:
(a) Put the access panel (2) in position and loosely install the studs (1).
(b) TORQUE the studs (1) to between 0.06 and 0.055 m.daN (5.31 and 4.87 lbf.in )

.
(3) Set CARGO COMPT LIGHT switch 8LU to the OFF position.
(4) Close aft cargo compartment door 826 (Ref. AMM TASK 52-30-00-860-002).
(5) In the center tank:
(a) Use Textile-Lint free Cotton - (Material No.14SBA1) to remove the Testing Medium-Leak Detection Bubbles - (Material No.14CBB1) from the PHVs and the vent pipe interface.
(6) Install right-hand access-cover 148AZ (Ref. AMM TASK 57-17-11-400-001).
(7) Remove the access platform(s).
(8) Close right-hand MLG door 744 (Ref. AMM TASK 32-12-00-410-001).

Subtask 28-28-49-865-055-A ** ON A/C NOT FOR ALL

C. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	FUEL/ACT AIR SOV/MAN/SPLY	64QH	J20
121VU	FUEL/ACT AIR SOV/AUTO/SPLY	63QH	J19
121VU	FUEL/ACT XFR VLV/MOT2	66QH	J18
121VU	FUEL/ACT XFR VLV/MOT1	65QH	J17
121VU	FUEL/INLET VLV/MOT1/AFT 2	84QH	L29
121VU	FUEL/INLET VLV/MOT1/MAN SPLY/AFT 1	46QH	L28
121VU	FUEL/ACT VENT VLV/MAN/SPLY	62QH	L21
121VU	FUEL/ACT VENT VLV/AUTO/SPLY	61QH	L20

Subtask 28-28-49-860-053-A ** ON A/C NOT FOR ALL

D. Aircraft Maintenance Configuration
(1) On ACT fuel control-panel 28VU:
(a) Release the ACT XFR MODE SEL P/BSW (the MAN legend goes off).

NOTE: ACT vent valve 234QM (in the center tank) opens and the pressure from the vent system releases.

Subtask 28-28-49-860-052-A ** ON A/C NOT FOR ALL

E. Put the aircraft back to its initial configuration.
(1) Refuel, defuel or transfer the fuel as necessary (Ref. AMM TASK 12-11-28-650-004), (Ref. AMM TASK 28-25-00-650-001) or (Ref. AMM TASK 28-25-00-869-001).
(2) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).

Subtask 28-28-49-942-051-A ** ON A/C NOT FOR ALL

F. Removal of Equipment
(1) If installed, remove the safety barriers.
(2) Remove the WARNING NOTICE(S).
(3) Remove the ground support and maintenance equipment, the special and standard tools and all other items.

[Rev.10 from 2021] 2026.04.02 06:17:59 UTC