Removal of the Low-Pressure Oxygen-Supply Solenoid-Valves

TASK 35-13-51-000-802-A
Removal of the Low-Pressure Oxygen-Supply Solenoid-Valves

WARNING: KEEP ALL HYDROCARBONS (FUELS, LUBRICANTS, ETC.) AWAY FROM ALL SOURCE 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.

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: 210
FIN: 3HT1 ** ON A/C NOT FOR ALL
FIN: 3HT2 ** ON A/C NOT FOR ALL

1. Reason for the Job
Self explanatory
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	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)
FOR [3HT1] (LP SOLENOID SUPPLY VALVE)
No specific	AR	BAG - VINYL
No specific	AR	BAG - VINYL, SEALED
No specific	AR	CAP - BLANKING
No specific	AR	PLUG - BLANKING, APPROVED FOR USE WITH OXYGEN
FOR [3HT2] (LP SOLENOID SUPPLY VALVE)
No specific	AR	BAG - VINYL
No specific	AR	BAG - VINYL, SEALED
No specific	AR	CAP - BLANKING
No specific	AR	PLUG - BLANKING, APPROVED FOR USE WITH OXYGEN

B. Work Zones and Access Panels

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

C. 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 35-00-00-860-001-A	Special Precautions When Working on a Gaseous Oxygen System
Low-Pressure Oxygen-Supply Solenoid-Valve

3. Job Set-up
Subtask 35-13-51-010-051-A ** 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 the ACCESS PLATFORM 2M (6 FT) in position at access door 812.
(3) Open access door 812.

Subtask 35-13-51-860-053-A ** ON A/C NOT FOR ALL

B. Aircraft Maintenance Configuration
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) In the cockpit, on the OXYGEN section of the overhead control and indicating panel 21VU:

Put a WARNING NOTICE(S) in position to tell persons not to push the CREW SUPPLY pushbutton switch.

(3) Fully close the two manual-shutoff valves of the crew oxygen-storage cylinders 5750HM1 and 5750HM2.
(4) Put a WARNING NOTICE(S) in position to tell persons not to open the manual-shutoff valves of the crew oxygen-storage cylinders 5750HM1 and 5750HM2.

Subtask 35-13-51-870-051-A ** ON A/C NOT FOR ALL

C. Bleeding of the Oxygen Systems
(1) 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).

(2) 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.
(a) Keep the PRESS TO TEST AND RESET control button and the PRESS TO TEST/EMERGENCY knob 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 button.

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.

1 Make sure that the PRESS TO TEST/EMERGENCY knob is not in the emergency position.
(3) 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.
(a) Keep the PRESS TO TEST AND RESET control button and the PRESS TO TEST/EMERGENCY knob 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 button.

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.

1 Make sure that the PRESS TO TEST/EMERGENCY knob is not in the emergency position.
(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).

Subtask 35-13-51-865-054-A ** ON A/C NOT FOR ALL

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	OXYGEN/CREW/OXY/SPLY	1HT	HA01

4. Procedure
Subtask 35-13-51-020-051-A ** ON A/C NOT FOR ALL

A. Removal of LP Oxygen-Supply Solenoid-Valves 3HT1 and/or 3HT2

CAUTION: USE A SECOND WRENCH TO APPLY COUNTERTORQUE TO THE UNION WHEN YOU DISCONNECT/CONNECT EQUIPMENT FROM FLEXIBLE HOSES AND RIGID TUBING. IF YOU DO NOT USE THE SECOND WRENCH, THERE IS A RISK THAT YOU WILL CAUSE DAMAGE TO THE HOSES AND TUBES.

(1) FOR [3HT1] (LP SOLENOID SUPPLY VALVE)
(a) Disconnect the electrical connector (3HT1A) (6) from the LP oxygen-supply solenoid-valve (3HT1) (5).
(b) Put a CAP - BLANKING on the disconnected electrical connector (3HT1A) (6).
(c) Disconnect the flexible pipe (8) and discard the bush (7).
(d) Put a PLUG - BLANKING, APPROVED FOR USE WITH OXYGEN on the flexible pipe (8).
(e) Put a BAG - VINYL around the disconnected flexible pipe (8).
(f) Disconnect the pipe (3) from the union (10) and from the LP oxygen-supply solenoid-valve (3HT1) (5).
(g) Remove the pipe (3) and discard the bushes (4) and (11).
(h) Put a PLUG - BLANKING, APPROVED FOR USE WITH OXYGEN on each end of the pipe (3).
(i) Put the pipe (3) in a BAG - VINYL.
(j) Put a PLUG - BLANKING, APPROVED FOR USE WITH OXYGEN on the union (10).
(k) Put the union (10) in a BAG - VINYL.
(l) Remove the screws (2), washers (1), nuts (9) and the LP oxygen-supply solenoid-valve (3HT1) (5).
(m) Put the LP oxygen-supply solenoid-valve (3HT1) (5) in a BAG - VINYL, SEALED.
(2) FOR [3HT2] (LP SOLENOID SUPPLY VALVE)
(a) Disconnect the electrical connector (3HT2A) (19) from the LP oxygen-supply solenoid-valve (3HT2) (18).
(b) Put a CAP - BLANKING on the disconnected electrical connector (3HT2A) (19).
(c) Disconnect the rigid pipe (16) from the union (14) and from the LP oxygen-supply solenoid-valve (3HT2) (18).
(d) Remove the rigid pipe (16) and discard the bushes (17) and (15).
(e) Put a PLUG - BLANKING, APPROVED FOR USE WITH OXYGEN on each end of the rigid pipe (16).
(f) Put the rigid pipe (16) in a BAG - VINYL.
(g) Put a PLUG - BLANKING, APPROVED FOR USE WITH OXYGEN on the union (14).
(h) Put the union (14) in a BAG - VINYL.
(i) Disconnect the pipe (21) from the union (24) and from the LP oxygen-supply solenoid-valve (3HT2) (18).
(j) Remove the pipe (21) and discard the bushes (20) and (23).
(k) Put a PLUG - BLANKING, APPROVED FOR USE WITH OXYGEN on each end of the pipe (21).
(l) Put the pipe (21) in a BAG - VINYL.
(m) Put a PLUG - BLANKING, APPROVED FOR USE WITH OXYGEN on the union (24).
(n) Put the union (24) in a BAG - VINYL.
(o) Remove the screws (12), washers (13), nuts (22) and the LP oxygen-supply solenoid-valve (3HT2) (18).
(p) Put the LP oxygen-supply solenoid-valve (3HT2) (18) in a BAG - VINYL, SEALED.

[Rev.10 from 2021] 2026.04.01 01:04:47 UTC