(e)
Oxygen, nitrogen, or air flows through each mask.
NOTE: The mask pintel must be pulled from mask shutoff
____ valve to start the oxygen flow (Fig 502).
(f)
Make sure that the indicators on the flow control units move to OFF.
(g)
Open these circuit breakers and install the DO-NOT-CLOSE tags:
1) 7D4 OXYGEN VALVE & IND
7D3 OXYGEN RESET PWR
(h)
Open the remaining shutoff valves on the supernumerary oxygen cylinder. 1) 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.
2) Close the shutoff valve one-fourth of a turn. 3) Install a lockwire on the shutoff valve.
NOTE: Use the 0.020 inch diameter coppper lockwire
____
(AMM 20-11-28/401).
S 865-185
(7)
If a oxygen cylinder was used to do the test, do the task: Oxygen System Servicing (Cylinder Replacement) (AMM 12-15-08/301), if it is necessary.
(8)
Close the access panels to the supernumerary oxygen cylinder.
S 865-186
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747-400 MAINTENANCE MANUAL
S 485-187
(9) If the oxygen bottle cart, or portable test cylinders is used to do the test, install as follows:
CAUTION: DO NOT TIGHTEN THE SHUTOFF VALVE ON EACH OXYGEN CYLINDER
_______ MORE THAN 25 POUND-INCHES. THIS CAN CAUSE DAMAGE TO THE SHUTOFF VALVE.
(a) Close the shutoff valve on each oxygen cylinder.
NOTE: The shutoff valve can be closed by hand which is
____
equivalent to 25 pound-inches.
WARNING:_______LOOSEN THE CONNECTIONS CAREFULLY. THE REMAINING OXYGEN CAN RELEASE WITH A LARGE FORCE AND CAN CAUSE INJURY TO PERSONS AND DAMAGE TO THE AIRPLANE AND EQUIPMENT.
(b)
Slowly remove the plug from the coupling assembly at point B (Fig. 501).
(c)
Connect the 0-30 psig pressure gauge to one test adapter on the continuous flow control unit (Fig. 501).
(d)
Connect the portable oxygen cylinder (or oxygen bottle cart output hose) to the coupling assembly at point B (Fig. 501).
(e)
Connect the oxygen bottle cart output hose to the other test adapter on the continuous flow control unit (Fig. 501).
(f)
Open the shutoff valve on the oxygen bottle cart (or portable test cylinder).
(g)
Remove the plug at point C (Fig 501) and connect a (0 - 2000 psig) pressure gauge.
(h)
Connect the 0 - 150 psi pressure gauge and the hose to one test port (pressure).
NOTE: The test port is found adjacent to the flow control
____
unit.
(i) Open the shutoff valve on the oxygen bottle cart (or portable test cylinder).
NOTE: The pressure gage at point C should read 600-830 PSIG.
____
(j) Pressurize the system to 20 psig.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
S 865-188
(10)
Move the SUPRNMRY OXYGEN switch on the P5 Pilot's Overhead Panel to ON.
S 735-189
(11)
Do a visual check these things occur:
(a) All the oxygen box doors drop.
(b) Oxygen, nitrogen, or air flows through each mask.
NOTE:____ The mask pintel must be pulled from mask shutoff
valve to start the oxygen flow (Fig 502).
(c) Indicator on the flow control unit moves to OFF.
S 865-190
(12)
Move the mask shutoff valve to the closed (up) position after verifying air flows through each mask.
S 865-191
(13)
Move the SUPRNMRY OXYGEN switch on the P5 Pilot's Overhead Panel to RESET (switch automatically moves back to NORMAL).
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