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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400 MAINTENANCE MANUAL
(d) Connect the 0-150 psi pressure gauge and hose to one test port (pressure).
NOTE: The test port is found adjacent to the flow control
____
unit.
S 865-139
(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.
G. Do the Alternate (Electrical) Actuation Test
S 865-140
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.
(1) Slowly open the portable test (or oxygen bottle cart) or one supernumerary oxygen cylinder shutoff valve (as applicable).
NOTE: The pressure gage (0-2000 psig) at point C should read
____
600-830 psig.
(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. NOTE: Use the 0.020 inch diameter copper lockwire
____
(AMM 20-11-28/401).
S 865-141
(2) Move the SUPRNMRY OXYGEN switch on the P5 Pilot's Overhead Panel to ON.
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35-21-00
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 747-400 MAINTENANCE MANUAL
(3) S 735-142Do a visual check that these events take place: (a) Initial pressure surge (within 20 seconds) is 35 to 110 psig as shown on the 0-150 psi pressure gage (installed at the test port (pressure)). (b) All the oxygen box doors unlatch. (c) SUPRNMRY OXY ON advisory message shows on the EICAS. (d) Indicator on the flow control unit moves to ON.
(4) S 865-143Move the SUPRNMRY OXYGEN switch on the P5 Pilot's Overhead Panel to RESET (switch automatically moves back to NORMAL).
(5) S 865-144Open some of the mask shutoff valves inside the oxygen boxes and bleed the system pressure down to zero (0) psig.
NOTE:____ The pressure in the oxygen line has to drop below 0.5 +/- 0.5 psig.
(6) S 735-145Do a visual check of the events that take occur: (a) Pressure bleeds down to 24 psig as shown on the 0-150 psi pressure gage. (b) If the pressure does not bleed down do the task: "Bleed Relief Valve Test" (Ref 35-21-08/501). (c) If it is necessary, do the task: Bleed Relief Valve Removal (AMM 35-21-08/401). (d) SUPRNMRY OXY ON advisory EICAS message does not show on the EICAS display. (e) Indicator on the flow control unit moves away from ON.
(7) S 865-146Move the SUPRNMRY OXYGEN switch on the P5 Pilot's Overhead Panel to RESET (switch automatically moves back to NORMAL).
(8) S 735-147Do a visual check to make sure the subsequent steps occur. (a) Pressure bleeds down through the opened mask shutoff valves. (b) Close the mask shutoff valves when system has completely bleed down.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400 MAINTENANCE MANUAL
S 865-148
CAUTION: DO NOT TIGHTEN THE SHUTOFF VALVE ON THE PORTABLE TEST OR ON THE
_______ PASSENGER OXYGEN CYLINDER MORE THAN 25 POUND-INCHES. THIS CAN CAUSE DAMAGE TO THE SHUTOFF VALVE.
(9) Close the shutoff valve on the portable test or supernumerary oxygen cylinder (as applicable).
NOTE: The shutoff valve can be closed by hand which is
____
equivalent to 25 pound-inches.
S 865-149
(10) Do the task: "Oxygen Mask Installation" (AMM 35-21-06/401).
H. Do the Simulated Automatic Actuation Test
S 215-150
(1) Make sure the oxygen boxes are kept in place by tape or other applicable means.
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