Removal of the Low-Pressure Oxygen Pressure-Switches

TASK 35-13-14-000-802-A
Removal of the Low-Pressure Oxygen Pressure-Switches

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: 4WV1 ** ON A/C NOT FOR ALL
FIN: 4WV2 ** 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 [5750HM1] (OXYGEN CYLINDER)
No specific	AR	BAG - VINYL
No specific	AR	CAP - BLANKING
No specific	AR	CAP - BLANKING, APPROVED FOR USE WITH OXYGEN
No specific	AR	TIE WRAP(S)
FOR [5750HM2] (OXYGEN CYLINDER)
No specific	AR	BAG - VINYL
No specific	AR	CAP - BLANKING
No specific	AR	CAP - BLANKING, APPROVED FOR USE WITH OXYGEN
No specific	AR	TIE WRAP(S)

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
TASK 35-10-00-870-801-A	Depressurization of the Crew Oxygen System (Manual Shutoff Valve(s) of the Crew Oxygen-Storage Cylinder(s) is (are) Closed)
TASK 52-41-00-010-002-A	Open the Avionics Compartment Doors for Access
Low-Pressure Oxygen Pressure-Switch

3. Job Set-up
Subtask 35-13-14-860-057-A ** ON A/C NOT FOR ALL

A. Aircraft Maintenance Configuration

WARNING: WHEN YOU DO WORK ON THE GASEOUS OXYGEN SYSTEM, MAKE SURE THAT YOU OBEY ALL THE APPLICABLE SAFETY PRECAUTIONS. IF YOU DO NOT OBEY THESE PRECAUTIONS, INJURY TO PERSONS AND/OR DAMAGE TO THE AIRCRAFT CAN OCCUR.

(1) Obey the special precautions when you do work on a gaseous oxygen system (Ref. AMM TASK 35-00-00-860-001).
(2) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).

Subtask 35-13-14-010-052-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Put an ACCESS PLATFORM 2M (6 FT) in position at access door 812.
(2) Open access door 812 (Ref. AMM TASK 52-41-00-010-002).
(3) Get access to the avionics compartment.

Subtask 35-13-14-860-053-A ** ON A/C NOT FOR ALL

C. Aircraft Maintenance Configuration
(1) Fully close the manual shutoff valves of the crew oxygen-storage cylinders (5750HM1 and 5750HM2).
(2) 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 35-13-14-870-051-A ** ON A/C NOT FOR ALL

D. Bleeding of the Crew Oxygen System
(1) Release the pressure from the crew oxygen system (Ref. AMM TASK 35-10-00-870-801).
(2) In the cockpit, on the OXYGEN section of overhead control and indicating panel 21VU:

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

Subtask 35-13-14-865-054-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
49VU	OXYGEN/CREW/OXY/SPLY	1HT	HA01

4. Procedure
Subtask 35-13-14-020-052-A ** ON A/C NOT FOR ALL

A. Removal of the Oxygen Pressure Switches 4WV1 and 4WV2
(1) FOR [5750HM1] (OXYGEN CYLINDER)

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.

(a) Disconnect the electrical connector (4WV1A) (3) from the pressure switch (4WV1) (2).
(b) Put a CAP - BLANKING on the disconnected electrical connector (4WV1A) (3).
(c) Put a CAP - BLANKING on the electrical port of the pressure switch (4WV1) (2).
(d) Remove the pressure switch (4WV1) (2) from the manifold (1).
(e) Put a CAP - BLANKING, APPROVED FOR USE WITH OXYGEN on the pneumatic port of the pressure switch (4WV1) (2).
(f) Put the pressure switch (4WV1) (2) in a BAG - VINYL.
(g) Put a CAP - BLANKING, APPROVED FOR USE WITH OXYGEN on the manifold (1).
(h) Put a BAG - VINYL on the disconnected port of the manifold (1).
1 Attach the BAG - VINYL with a TIE WRAP(S).
(2) FOR [5750HM2] (OXYGEN CYLINDER)

(a) Disconnect the electrical connector (4WV2A) (6) from the pressure switch (4WV2) (5).
(b) Put a CAP - BLANKING on the disconnected electrical connector (4WV2A) (6).
(c) Put a CAP - BLANKING on the electrical port of the pressure switch (4WV2) (5).
(d) Remove the pressure switch (4WV2) (5) from the manifold (4).
(e) Put a CAP - BLANKING, APPROVED FOR USE WITH OXYGEN on the pneumatic port of the pressure switch (4WV2) (5).
(f) Put the pressure switch (4WV2) (5) in a BAG - VINYL.
(g) Put a CAP - BLANKING, APPROVED FOR USE WITH OXYGEN on the manifold (4).
(h) Put a BAG - VINYL on the disconnected port of the manifold (4).
1 Attach the BAG - VINYL with a TIE WRAP(S).

[Rev.10 from 2021] 2026.04.01 01:04:30 UTC