(b)  
Remove the fasteners which attach the oxygen box to the brackets.

 (c)  
Pull the oxygen box out of the panel or partition until you can get to the inlet hose.

 (d)  
Disconnect the inlet hose from the unitized valve assembly or (if required) from the distribution lines.

 (e)  
Remove the oxygen box.

 S 494-020
 (5)  Install a protective cap or a plug to the open lines, fittings, or the ports to prevent contamination of the system.
 (a)  
Tighten the nylon caps to 10-15 pound-inches.

 (b)  
Tighten the steel caps to 35-45 pound-inches.

 TASK 35-21-19-404-019
 3. Supernumerary Oxygen Box Installation (Fig. 401)
_____________________________________
 A. Standard Tools and Equipment
 (1)  Rod - Metal, 3/32 inch in diameter
 B. References
 (1)  
AMM 35-00-00/201, Oxygen

 (2)  
IPC 35-21-05

 C. Access
 (1)  Location Zone
 200 Upper Half Fuselage

 D. Procedure
 S 914-030
 (1)  Read and obey the safety precautions and general instructions before you do the maintenance (AMM 35-00-00/201).
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747-400 MAINTENANCE MANUAL
 S 434-014
 (2)  
Remove the protective caps or the plugs from the lines, fittings, or the ports.

 S 214-031

 (3)  
Examine the fitting (threads) to make sure they are clean.

 S 424-015

 (4)  
Install the oxygen box.

 (a)  
Point the oxygen box in the direction of the panel or the partition.

 (b)  
Connect the inlet hose to the unitized valve assembly or to the distribution lines (as necessary).

 (c)  
Put the oxygen box into the panel or the partition.

 (d)  
Install the fasteners to the connect the oxygen box to the brackets.

 NOTE: There must not be gaps between the panel or the
____ partition and the oxygen box.
 S 434-026
 (5)  Close the oxygen box door:
 (a)  
Lift the oxygen box door near to the oxygen box.

 (b)  
Carefully put a 1/4-inch Allen wrench or metal rod through the release access hole and lift the plunger on the latch.

 (c)  
Lift the oxygen box door until it engages the latch and remove the Allen wrench or metal rod.

 E. Installation Test
 S 864-044
 (1)  Use tape or other devices to loosely keep 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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 (2)  S 714-045Do the Passenger Oxygen Mask Drop Test procedure to make sure that the oxygen boxes are installed correctly and operates as intended (AMM 35-21-00/501).
 (3)  S 214-048Make sure that the oxygen box doors unlatch opened.
 (4)  S 864-047Close the oxygen box doors.
 (5)  S 864-046Remove the tape or other devices used to loosely keep the oxygen box doors in the up position.
 S 864-038

 WARNING:_______OPEN THE SHUTOFF VALVE ON EACH OXYGEN CYLINDER SLOWLY. IF NOT, 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.
 (6) Open the shutoff valve on each oxygen cylinder:
 (a) Slowly turn the shutoff valve until it is fully open.
 NOTE: The shutoff valve can be closed by hand which is
____ equivalent to 25 pound-inches.
 (b)
Close the shutoff valve one-fourth of a turn.

 (c)
Install a lockwire on the shutoff valve.
　
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