Leak Test of the Crew LP Oxygen-System

TASK 35-10-00-790-001-A
Leak Test of the Crew LP Oxygen-System

WARNING: DO NOT FILL OR REPLACE A CREW OXYGEN CYLINDER OR REPLACE A VALVE ASSEMBLY ON THE CREW OXYGEN SYSTEM WHEN YOU FUEL OR DEFUEL THE AIRCRAFT. KEEP ALL HYDROCARBONS (FUELS, LUBRICANTS, ETC.) AWAY FROM ALL SOURCES OF OXYGEN. OXYGEN BECOMES EXPLOSIVE WHEN IT TOUCHES HYDROCARBONS.

WARNING: CLEAN THE TOOLS AND MAKE SURE YOUR HANDS ARE CLEAN TO PREVENT CONTAMINATION OF THE OXYGEN SYSTEM.

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

CAUTION: PUT DRY AND CLEAN METAL OR PLASTIC PLUGS ON ALL PIPES OR UNITS THAT YOU REMOVE TEMPORARILY. THEN PUT EACH PIPE OR UNIT IN A SEALED VINYL BAG. IF YOU DO NOT OBEY THESE INSTRUCTIONS, CONTAMINATION OF THE OXYGEN SYSTEM CAN OCCUR.

ZONE: 123
ZONE: 125
ZONE: 210

1. Reason for the Job

NOTE: There is an alternative procedure for this procedure. For the other procedure, refer to the AMM TASK 35-10-00-790-001-A01.

To make sure that there are no leaks in the LP oxygen system. Do the test with nitrogen. Nitrogen has the same physical properties as oxygen.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 2M (6 FT)
No specific	AR	GAGE 10 BAR (145 PSI) - PRESSURE
No specific	AR	NITROGEN COMPRESSED SOURCE - GROUND
No specific	AR	VALVE - BLEED
No specific	AR	VALVE - ISOLATION
No specific	AR	VALVE - REDUCING, PRESSURE
No specific	AR	WARNING NOTICE(S)

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.14CCB6)	Testing Medium-Leak Detection - Oxygen System

C. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
123	NOSE GEAR WELL
125	LATERAL AVIONIC COMPARTMENT
210	CKPT,FWD COMPT BHD TO FLT COMPT BULKHEAD
812

D. Referenced Information

REFERENCE	DESIGNATION
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 35-00-00-860-001-A	Special Precautions When Working on a Gaseous Oxygen System
Prepare for the Test ** ON A/C NOT FOR ALL
Test Installation

3. Job Set-up
Subtask 35-10-00-010-054-A ** ON A/C NOT FOR ALL

A. Get Access
(1) Put the ACCESS PLATFORM 2M (6 FT) in position at access door 812.
(2) Open access door 812.
(3) In the avionics compartment, open the cover of the oxygen compartment.

Subtask 35-10-00-010-054-B ** ON A/C NOT FOR ALL

A. Get Access
(1) Obey the special precautions when you do work on a gaseous oxygen system (Ref. AMM TASK 35-00-00-860-001).
(2) Put a WARNING NOTICE(S) in position to tell persons not to release the CREW SUPPLY pushbutton switch.
(3) Energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-861-002).
(4) Put the ACCESS PLATFORM 2M (6 FT) in position at access door 812.
(5) Open access door 812.

Subtask 35-10-00-865-050-A

B. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	OXYGEN/CREW/OXY/SPLY	1HT	HA01

Subtask 35-10-00-860-050-A ** ON A/C NOT FOR ALL

C. Aircraft Maintenance Configuration
(1) Obey the special precautions when you do work on a gaseous oxygen system (Ref. AMM TASK 35-00-00-860-001).
(2) Fully close the valve of the oxygen storage cylinder (5750HM).
(3) Put a WARNING NOTICE(S) in position to tell persons not to open the valve of the oxygen storage cylinder.
(4) Energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-861-002).
(5) Make sure that the avionics compartment and the cockpit have a good airflow.
(6) Bleed the oxygen system:
(a) In the cockpit, on the OXYGEN section of the overhead control and indicating panel 21VU, push the CREW SUPPLY pushbutton switch (the OFF legend goes off).
(b) Put a WARNING NOTICE(S) in position to tell persons not to release the CREW SUPPLY pushbutton switch.
(c) On one oxygen-mask stowage box, push and hold the PRESS TO TEST AND RESET control lever.
At the same time, push and hold the PRESS TO TEST/EMERGENCY knob on the mask regulator.
1 Keep them pushed for a minimum of three seconds.

NOTE: During this time, the flow rate indicator changes from yellow to black and the volume of the sound of the oxygen flow decreases.

(d) When the flow rate indicator is black and when you no longer hear the sound of the oxygen flow:

Release the PRESS TO TEST/EMERGENCY knob.
Release the PRESS TO TEST AND RESET control lever.

(e) Make sure that the PRESS TO TEST/EMERGENCY knob is not in the EMERGENCY position. If it is in the EMERGENCY position, there can be a leak of oxygen.

Subtask 35-10-00-480-050-A ** ON A/C NOT FOR ALL

D. Preparation of the Test Installation

Test Installation ** ON A/C NOT FOR ALL

(1) Get a NITROGEN COMPRESSED SOURCE - GROUND.
(2) Get a VALVE - REDUCING, PRESSURE.
(3) Get a VALVE - BLEED.
(4) Get an VALVE - ISOLATION.
(5) Get a GAGE 10 BAR (145 PSI) - PRESSURE.
(6) Get a union (1) 110111-03 COUPLING-OXYGEN QUICK DISCONNECT802857-01 COUPLING or equivalent.
(7) Assemble the test installation

Test Installation ** ON A/C NOT FOR ALL

(8) Remove the blanking cap from the oxygen-system test-port 5755HM.
(9) Connect the test installation to the oxygen-system test-port 5755HM.

Subtask 35-10-00-860-050-C ** ON A/C NOT FOR ALL

E. Aircraft Maintenance Configuration

Prepare for the Test ** ON A/C NOT FOR ALL

(1) Fully close the manual shutoff valve (2) of the crew oxygen-storage cylinder (5750HM1).
(2) Put a WARNING NOTICE(S) in position to tell persons not to open the manual shutoff valve (2) of the crew oxygen-storage cylinder (5750HM1).
(3) Fully close the manual shutoff valve (3) of the crew oxygen-storage cylinder (5750HM2).
(4) Put a WARNING NOTICE(S) in position to tell persons not to open the manual shutoff valve (3) of the crew oxygen-storage cylinder (5750HM2).
(5) Make sure that the avionics compartment and the cockpit have a good airflow.
(6) Do the bleeding of the two oxygen systems:
(a) In the cockpit, on the OXYGEN section of the overhead control and indicating panel 21VU, push the CREW SUPPLY pushbutton switch (the OFF legend goes off).
(b) On the Captain oxygen-mask stowage-box, push and hold the PRESS TO TEST AND RESET control button.
At the same time, push and hold the PRESS TO TEST/EMERGENCY knob on the mask regulator.
1 Keep them pushed for a minimum of three seconds.

NOTE: During this time, the flow rate indicator changes from yellow to black and the volume of the sound of the oxygen flow decreases.

2 When the flow rate indicator is black and when you no longer hear the sound of the oxygen flow:

Release the PRESS TO TEST/EMERGENCY knob.
Release the PRESS TO TEST AND RESET control button.

3 Check of the position of the PRESS TO TEST/EMERGENCY knob

WARNING: MAKE SURE THAT THE PRESS TO TEST/EMERGENCY KNOB IS NOT IN THE EMERGENCY POSITION. IF IT IS IN THE EMERGENCY POSITION, THERE CAN BE A LEAK OF OXYGEN.

a Make sure that the PRESS TO TEST/EMERGENCY knob is not in the EMERGENCY position.
(c) On the First-Officer oxygen-mask stowage-box, push and hold the PRESS TO TEST AND RESET control button.
At the same time, push and hold the PRESS TO TEST/EMERGENCY knob on the mask regulator.
1 Keep them pushed for a minimum of three seconds.

NOTE: During this time, the flow rate indicator changes from yellow to black and the volume of the sound of the oxygen flow decreases.

2 When the flow rate indicator is black and when you no longer hear the sound of the oxygen flow:

Release the PRESS TO TEST/EMERGENCY knob.
Release the PRESS TO TEST AND RESET control button.

3 Check of the position of the PRESS TO TEST/EMERGENCY knob

WARNING: MAKE SURE THAT THE PRESS TO TEST/EMERGENCY KNOB IS NOT IN THE EMERGENCY POSITION. IF IT IS IN THE EMERGENCY POSITION, THERE CAN BE A LEAK OF OXYGEN.

a Make sure that the PRESS TO TEST/EMERGENCY knob is not in the EMERGENCY position.

Subtask 35-10-00-480-050-C ** ON A/C NOT FOR ALL

F. Prepare the Test Installation

Prepare for the Test ** ON A/C NOT FOR ALL

Test Installation ** ON A/C NOT FOR ALL

(8) At 5755HM1:
(a) Remove the blanking cap (5) from the oxygen-system test port (5755HM1) (4).
(b) Connect the union (1) of the test installation to the oxygen-system test port (5755HM1) (4).

4. Procedure
Subtask 35-10-00-860-051-A

A. Leak Test of the Captain LP Oxygen-System
(1) Open the nitrogen source. Use the pressure reducing valve to set the pressure to 94 psi (6.48 bar).
(2) Close the isolation valve and the nitrogen source.
(3) Keep the system pressurized for a minimum of 30 minutes.
(4) Make sure that the value on the pressure gage does not decrease.
(a) If the pressure decreases, find the leak with Testing Medium-Leak Detection - Oxygen System (Material No.14CCB6) .
(b) Replace the defective component and do the test again.
(5) When the pressure is stable, open the isolation valve.
(6) Open the bleed valve.

Subtask 35-10-00-614-050-A ** ON A/C NOT FOR ALL

B. Disconnect the Test Installation
(1) Disconnect the test installation from the oxygen-system test-port 5755HM.
(2) Put the blanking cap on the oxygen-system test-port 5755HM.
(3) Put the oxygen storage cylinder in the serviceable condition.
(a) Slowly open the valve of the oxygen storage cylinder by 3 to 4 turns.
(b) Stop for 90 seconds to let the pressure become stable.
(c) Fully open the valve of the oxygen storage cylinder.
(4) Bleed the oxygen system:
(a) On the oxygen-mask stowage box, push and hold the PRESS TO TEST AND RESET control lever.
At the same time, push and hold the PRESS TO TEST/EMERGENCY knob on the mask regulator.
1 Keep them pushed for a minimum of three seconds.

NOTE: During this time, the flow rate indicator changes from yellow to black and the volume of the sound of the oxygen flow decreases.

(b) When the flow rate indicator is black and when you no longer hear the sound of the oxygen flow:

Release the PRESS TO TEST/EMERGENCY knob.
Release the PRESS TO TEST AND RESET control lever.

(c) Make sure that the PRESS TO TEST/EMERGENCY knob is not in the EMERGENCY position. If it is in the EMERGENCY position, there can be a leak of oxygen.
(5) Do this bleeding procedure for all of the oxygen-mask stowage boxes.
(6) In the cockpit, on the OXYGEN section of the overhead control and indicating panel 21VU, release the CREW SUPPLY pushbutton switch (the OFF legend comes on).

Subtask 35-10-00-614-050-C ** ON A/C NOT FOR ALL

B. Disconnect the Test Installation
(1) Disconnect the test installation from the oxygen-system test port (5755HM).
(2) Put the blanking cap on the oxygen-system test port (5755HM).
(3) Put the oxygen storage cylinder in the serviceable condition.
(a) Turn the valve of the oxygen storage cylinder very slowly until it is fully open.
(4) Bleed the oxygen system:
(a) On the oxygen-mask stowage box, push and hold the PRESS TO TEST AND RESET control lever.
At the same time, push and hold the PRESS TO TEST/EMERGENCY knob on the mask regulator.
1 Keep them pushed for a minimum of three seconds.

NOTE: During this time, the flow rate indicator changes from yellow to black and the volume of the sound of the oxygen flow decreases.

(b) When the flow rate indicator is black and when you no longer hear the sound of the oxygen flow:

Release the PRESS TO TEST/EMERGENCY knob.
Release the PRESS TO TEST AND RESET control lever.

Subtask 35-10-00-614-050-E ** ON A/C NOT FOR ALL

B. Disconnection/Connection of the Test Installation

Prepare for the Test ** ON A/C NOT FOR ALL

(1) At 5755HM1:
(a) Disconnect the test installation from the oxygen-system test port (5755HM1) (4).
(b) Put the blanking cap (5) on the oxygen-system test port (5755HM1) (4).
(2) At 5755HM2:
(a) Remove the blanking cap (5) from the oxygen-system test port (5755HM2) (4).
(b) Connect the union (1) of the test installation to the oxygen-system test port (5755HM2) (4).

Subtask 35-10-00-860-065-A ** ON A/C NOT FOR ALL

C. Leak Test of the First-Officer LP Oxygen-System
(1) Open the nitrogen source. Use the pressure reducing valve to set the pressure to 94 psi (6.48 bar).
(2) Close the isolation valve and the nitrogen source.
(3) Keep the system pressurized for a minimum of 30 minutes.
(4) Make sure that the value on the pressure gage does not decrease.
(a) If the pressure decreases, find the leak with Testing Medium-Leak Detection - Oxygen System (Material No.14CCB6) .
(b) Replace the defective component and do the test again.
(5) When the pressure is stable, open the isolation valve.
(6) Open the bleed valve.

Subtask 35-10-00-614-056-A ** ON A/C NOT FOR ALL

D. Put the aircraft back to its initial configuration.
(1) At 5755HM2:
(a) Disconnect the test installation from the oxygen-system test port (5755HM2) (4).
(b) Put the blanking cap (5) on the oxygen-system test port (5755HM2) (4).
(2) Put the crew oxygen-storage cylinders in the serviceable condition.
(a) Turn the manual shutoff valve (2) of the crew oxygen-storage cylinder (5750HM1) very slowly until it is fully open.
(b) Turn the manual shutoff valve (3) of the crew oxygen-storage cylinder (5750HM2) very slowly until it is fully open.
(3) Do the bleeding of the two oxygen systems:
(a) On the Captain oxygen-mask stowage-box, push and hold the PRESS TO TEST AND RESET control button.
At the same time, push and hold the PRESS TO TEST/EMERGENCY knob on the mask regulator.
1 Keep them pushed for a minimum of three seconds.

NOTE: During this time, the flow rate indicator changes from yellow to black and the volume of the sound of the oxygen flow decreases.

2 When the flow rate indicator is black and when you no longer hear the sound of the oxygen flow:

Release the PRESS TO TEST/EMERGENCY knob.
Release the PRESS TO TEST AND RESET control button.

3 Check of the position of the PRESS TO TEST/EMERGENCY knob

WARNING: MAKE SURE THAT THE PRESS TO TEST/EMERGENCY KNOB IS NOT IN THE EMERGENCY POSITION. IF IT IS IN THE EMERGENCY POSITION, THERE CAN BE A LEAK OF OXYGEN.

a Make sure that the PRESS TO TEST/EMERGENCY knob is not in the EMERGENCY position.
(b) Do this bleeding procedure for all of the remaining oxygen-mask stowage boxes.
(4) In the cockpit, on the OXYGEN section of the overhead control and indicating panel 21VU, release the CREW SUPPLY pushbutton switch (the OFF legend comes on).

5. Close-up
Subtask 35-10-00-942-050-A

A. Put the aircraft back to its initial configuration.
(1) Make sure that the work area is clean and clear of tools and other items.
(2) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).

Subtask 35-10-00-410-050-A ** ON A/C NOT FOR ALL

B. Close Access
(1) Close the cover of the oxygen compartment.
(2) Remove the WARNING NOTICE(S).
(3) Close access door 812.
(4) Remove the access platform(s).

Subtask 35-10-00-410-050-B ** ON A/C NOT FOR ALL

B. Close Access
(1) Remove the WARNING NOTICE(S).
(2) Close access door 812.
(3) Remove the access platform(s).

[Rev.10 from 2021] 2026.04.01 01:03:48 UTC