Removal of the Low-Pressure Oxygen Pressure-Switch

TASK 35-13-14-000-001-A
Removal of the Low-Pressure Oxygen Pressure-Switch

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: 125
ZONE: 210
FIN: 4WV ** 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	CAP - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

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

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 35-00-00-860-001-A	Special Precautions When Working on a Gaseous Oxygen System
Oxygen Pressure Switch

3. Job Set-up
Subtask 35-13-14-010-051-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.

Subtask 35-13-14-860-050-A ** ON A/C NOT FOR ALL

B. 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 the WARNING NOTICE(S) in position to tell persons not to open the valve of the oxygen storage cylinder.
(4) Energize the ground service network from the external power (Ref. AMM TASK 24-42-00-861-001).

Subtask 35-13-14-870-050-A ** ON A/C NOT FOR ALL

C. Bleeding of the oxygen system
(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 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.
(a) 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.

(3) 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.

(4) 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) 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).
Put a WARNING NOTICE(S) in position to tell persons not to push the CREW SUPPLY pushbutton switch.

Subtask 35-13-14-865-050-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 35-13-14-020-051-A ** ON A/C NOT FOR ALL

A. Removal of the Oxygen Pressure Switch
(1) Disconnect the electrical connector (3) from the pressure switch (2).
(2) Put a CAP - BLANKING on the disconnected electrical connector (3).
(3) Remove the pressure switch (2) from the manifold (1).
(4) Put a CAP - BLANKING on the manifold (1).

[Rev.10 from 2021] 2026.04.01 01:04:27 UTC