10 MINUTES BEFORE THIRD ATTEMPT.
(1) Open door electrically.
NOTE: The door is opened electrically by extending the master
____ latch lock handle and holding the door control switch in the OPEN position until the door is full open and limit switches shut off power. The sequence of events during door opening is as follows:
(a)
The green PWR ON indicator light on both door control panels is on when the SIDE CARGO DOOR CONTROL circuit breaker on P415 panel is closed. With the door closed and latched, and master latch lock handle closed, the green LATCHES CLOSED lights and door open lights on both control panels will be off.
(b)
Extending the master latch lock handle (forced out by spring force) rotates the master latch lock torque tube which retracts the ten latch lock sectors to free the latch cams for rotation. Linkage from the master latch lock torque tube rotates the pressure relief door torque tube to open the pressure relief doors and relieve pressure in the compartment before the door is opened. As the aft pressure relief door moves away from the fully closed position, the door warning switch closes to illuminate the door warning message on EICAS.
(c)
When the lock sectors are fully retracted, the master latch lock switch closes to provide control power to the control circuit and turn on the LATCHES CLOSED lights through the energized latch closed relay (K5). See Fig. 2 for electrical schematic and Fig. 3 for switch location and mechanism schematic.
(d)
Placing either door control switch in OPEN energizes the hook restraint solenoids to free the hook torque tubes for rotation and provides 28-volt dc control power to the latch actuator through the de-energized latches open relay (K10). As the latch mechanism moves away from the closed position, the latch closed switch opens, de-energizing the latched closed relay (K5) to enable door operation to be reversed at any point thereafter. The de-energized latch closed relay turns off the LATCHES CLOSED lights. When the latch mechanism approaches full open, the forward and aft midspan latch open switches close to energize the midspan latch open relays (K3 and K4).
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MAINTENANCE MANUAL
Side Cargo Door Simplified Schematic
Figure 3
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
(e)
(f)
(g)
(h)
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MAINTENANCE MANUAL
When the latch mechanism reaches full open, the latches open switch closes to energize the latches open relay (K10). When the latches open relay is energized, power is removed from the latch actuator and transferred to the hook actuators through the energized midspan latch open relays (K3 and K4), the closed contacts of the forward and aft hook restraint soleniods, and relaxed contacts of the forward and aft hook open relays (K8 and K9). As the hooks move from their closed positions, the hook closed switches open, de-energizing the hook closed relays (K6 and K7) to enable door operation to be reversed.When the hooks are fully open (door open approximately 3 inches), the hook open switches close, energizing the hook open relays (K8 and K9). When both hook open relays are energized, power is removed from the hook actuators and transferred to the lift power unit to open the door. As the lift mechanism rotary actuator arms move away from the door closed position, the door down switches open, de-energizing door down relays (K1 and K2) to enable door operation to be reversed. During the door opening cycle, the brake unit of the gearbox and brake assembly ratchets freely, offering no resistance to door movement.When the door reaches the full up positions, one set of contacts in the door up switches open to remove power from the lift power unit. The second set of contacts close to turn on the DOOR UP lights on the control panels. Power is removed and the indicator lights turn on when either door up switch opens. The midspan latch open relays (K3 and K4), latches open relay (K10), and hook open relays (K8 and K9) remain energized as long as the door is open. The door restraint soleniods remain energized until the control switch is released. All other relays are de-energized and sequence switches in position to enable the door to be closed.If one rotary actuator arm leads the other as the door opens, the leading arm will contact its upstop and slip clutches in the power unit will allow the lagging arm to continue to drive until its limit switch shuts off power to the power unit. 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 舱门 DOORS 2(70)
