(8)  
35-21-08/501, Bleed Relief Valve

 (9)  
WDM 35-21-11, 35-21-12, 35-21-13

 (10)
 SSM 35-21-01

 F. Access
 (1)  Location Zones 124 Forward Cargo Container Compartment, Aft Half Right 200 Upper Half Fuselage
 G. Preconditions
 S 865-049
 (1)  The systems that follow must be installed and serviceable to complete this test:
 (a)  
Electrical Power (AMM 24-22-00/201).

 (b)  
Integrated Display System (IDS) (AMM 31-61-00/501).

 (c)  
Oxygen System (AMM 35-00-00/201).

 (d)  
Airplane in Ground Mode (AMM 32-09-02/201).

 H. Procedure
 S 915-050
 (1)  
Read and obey the safety precautions and general instructions before you do the maintenance (Ref 35-00-00/201).

 S 795-051

 (2)  
Do the task: "Oxygen System High Pressure Leak Test"

 S 795-052

 (3)  
Do the task: "Oxygen System Low Pressure Leak Test"

 I. Prepare for a Functional Test of the Pressure Reducer
 S 015-053
 (1)  Open the access panels to the oxygen cylinders.
 NOTE: The oxygen cylinders are attached by snaps and velcro
____
 tape.

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 35-21-00
 ALL  ú ú 01B Page 512 ú Feb 18/01
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A
747-400
MAINTENANCE MANUAL

 S 865-054
 CAUTION: DO NOT TIGHTEN THE SHUTOFF VALVE ON EACH OXYGEN CYLINDER MORE
_______ THAN 25 POUND-INCHES. THIS CAN CAUSE DAMAGE TO THE SHUTOFF VALVE.
 (2)  Close the shutoff valve on each oxygen cylinder.
 NOTE: The shutoff valve can be closed by hand which is
____
 equivalent to 25 pound-inches.

 S 485-055
 WARNING:_______LOOSEN THE PLUG CAREFULLY. THE REMAINING OXYGEN CAN RELEASE WITH A LARGE FORCE AND CAUSE THE TEMPERATURE TO INCREASE. THIS CAN START AN IGNITION WITH THE OXYGEN AND CAUSE INJURY TO PERSONS AND DAMAGE TO THE AIRPLANE AND EQUIPMENT.
 (3)  
Remove the plug at point C (Fig. 501) and connect a 0-2000 psi pressure gauge to the supply manifold.

 S 485-056

 (4)  
Remove the plug at point B on the pressure reducer on the oxygen cylinder to be tested (Fig. 501).

 S 485-057

 (5)  
Connect the portable test cylinder to the oxygen line.

 S 865-058

 (6)  
Supply the electrical power (Ref 24-22-00/201).

 S 865-059

 (7)  
Remove the DO-NOT-CLOSE tags and close these circuit breakers:

 (a)  P6 Overhead Circuit Breaker Panel
 1) 7D4 OXYGEN VALVE & IND
 2) 7D3 OXYGEN RESET PWR

 S 435-060
 (8)  Use tape or other applicable means to loosely install the oxygen box doors in the up position.
 NOTE: This permits the door to unlatch, but does not let the
____
 oxygen masks fall.

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 ALL  ú ú 01B Page 513 ú Feb 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 035-061
 (9)  Remove two caps from the weld outlets on the distribution line, for the low pressure, in the passenger cabin.
 J. Do the Functional Test of the Pressure Reducer
 S 865-062
 WARNING: OPEN THE SHUTOFF VALVES ON THE PORTABLE TEST CYLINDER SLOWLY.
_______ HIGH TEMPERATURES CAN OCCUR WHICH CAN START AN IGNITION WITH THE OXYGEN. THIS CAN CAUSE INJURY TO PERSONS AND DAMAGE TO THE AIRPLANE AND EQUIPMENT.
 (1)  
Open the shutoff valve on the portable test cylinder, and pressurize the line to 1500 psig.

 S 735-063

 (2)  
Do a visual check of the initial pressure on the 0-2000 psi pressure gage to make sure it is between 600 and 830 psig.

 NOTE: The pressure reducer seat will permit leaks downstream
　
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