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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400 MAINTENANCE MANUAL
(b) Remove the lockwire or cotter pin which is used to hold the pressure cap on the crew oxygen cylinder.
WARNING: REMOVE THE PRESSURE CAP SLOWLY TO RELEASE THE GAS SLOWLY.
_______ GAS PRESSURE CAN CAUSE THE CAP TO COME OFF WITH A FORCE THAT CAN CAUSE INJURIES TO PERSONNEL.
(c)
Slowly remove the cap from the oxygen cylinder.
(d)
Do not disengage the last screw threads until all of the gas pressure is released.
(e)
Do not cut or disengage the chain after you remove the cap. Keep the cap on the shutoff valve.
(f)
Remove the protective caps or plugs from the lines, fittings or ports and airplane lines.
(g)
Examine the thread fittings to make sure that they are clean.
S 423-235
(2) Install the oxygen cylinder:
(a) Put the oxygen cylinder on the rollers and push it aft until the cylinder is against the aft restraining bracket.
NOTE: Put the cylinder in postion to permit the connection of
____ the lines. The hoses must not bind or close off. The pressure gage on the cylinder should face down on the upper cylinder and up on the lower cylinder.
(b)
Put the front bracket over the forward end of the cylinder and install the T-bolt nut. 1) Make sure that the cylinder cannot move. 2) Make sure that the threads of the T-bolt extend through the
nut plate until you can see the chamfer.
(c)
Connect the lines: 1) Connect the overboard discharge line at the B-nut, and make
sure the connection is tight. 2) Move the coupling assembly into its position.
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747-400 MAINTENANCE MANUAL
3) Connect the B-nut on the crew supply line. 4) Connect the coupling nut on the high pressure cylinder, and tighten to a torque of 650 to 700 pound-inches.
WARNING: OPEN THE SHUTOFF VALVE ON OXYGEN CYLINDERS SLOWLY.
_______ IF YOU OPEN IT QUICKLY, HIGH TEMPERATURES IN THE LINES CAN OCCUR. THIS CAN CAUSE INJURIES TO PERSONNEL AND DAMAGE TO THE AIRPLANE AND EQUIPMENT.
(d) Slightly open the oxygen cylinder shutoff valve to let the system pressurize slowly.
CAUTION: TIGHTEN THE SHUTOFF VALVE ON EACH OXYGEN CYLINDER WITH
_______ YOUR HAND (25 INCH-POUNDS, 2.8 NEWTON-METERS). TOO MUCH TORQUE CAN CAUSE DAMAGE TO THE SHUTOFF VALVE.
(e)
Close the shutoff valve.
(f)
Use leak detection compound to make sure that the connections do not have leaks.
(g)
If there are leaks, do the applicable repairs to the
connections, and do the check again.
(h)
If no leaks are found, remove the leak detection compound with a clean cotton cloth.
S 843-233
(3) Prepare to make the oxygen system serviceable:
(a)
Install the tubing clamps, if you removed them.
(b)
Slowly turn the shutoff valve with your hand until it is fully open (a maximum of 25 inch-pounds, 2.8 newton-meters).
(c)
Close the shutoff valve one quarter of a turn.
(d)
Use 0.020 inch diameter copper lockwire to safety the shutoff valve (AMM 20-11-28/401).
(e)
Remove the DO-NOT-CLOSE tag and close this circuit breaker:
1) On the overhead circuit breaker panel, P7: a) 7D4, OXYGEN VALVE & IND 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747-400 AMM 飞机维护手册 SERVICING 1(91)
