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ALL ú ú 01 Page 4 ú Jun 10/88
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
DRIVE PORT
A-A
Forward Cargo Door Lift Mechanism Figure 1 (Sheet 4)
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ALL ú ú 01 Page 5 ú Feb 10/89
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A
747-400
MAINTENANCE MANUAL
A. The master latch lock mechanism (Detail B) includes a manual handle which controls the master latch lock mechanism from either inside or outside the airplane. Operation of the handle, connected by two bellcranks, two cranks, and three pushrods rotates the lock torque tube to position the eight lock sectors and open or close the two pressure relief doors. The pressure relief doors are controlled by a crank, located near the aft end of the master latch lock torque tube, connected to the pressure relief door torque tube by a system of bellcranks, cranks, and pushrods. Each pressure relief door is connected to the pressure relief door torque tube by two cranks and a pushrod. The pressure relief doors remain open when the master latch lock handle is open to prevent pressurization of the airplane. The pressure relief doors also open to limit pressure difference to a permitted level if the external pressure becomes higher than the pressure inside the airplane.
B. The latch mechanism consists of an electrical actuator which rotates the latch torque tube. The latch torque tube is connected by a system of pushrods and bellcranks, to latch or unlatch the eight lower latch cams and two midspan latch cams (Detail C).
C. The hook mechanism consists of an electrical actuator which rotates the hook torque tube. The hook torque tube is connected to the hook bellcrank by pushrods, to position the forward and aft hooks. The hook return spring, which is attached to the bellcrank, applies a spring force to hold the hooks in the open position (detail D).
D. The lift mechanism consists of the lift actuator, two drive torque tubes, two rotary actuators, and two links. The lift actuator, which has an auxiliary manual drive, operates the drive torque tubes connected to the two rotary actuators. The rotary actuators, planetary gear reduction units, are linked to the door support brackets (Detail E). The auxiliary manual drive consists of a manual drive socket on the bottom of the actuator for operation from within the cargo compartment and a flexible shaft extending from a male square drive on top of the actuator to a receptacle above the door for operation from outside (Section A-A). The flexible shaft connects the exterior manual drive socket, which rotates on a bearing in the housing, to the lift actuator.
E. The pressure relief door shrouds prevent the doors from being driven closed by the out-rushing air flow through the openings in the event that the master lock handle is in the unlocked position when the airplane pressurization begins. The pressure relief doors prevent airplane pressurization if the forward/aft cargo door is not correctly locked.
3. Operation
_________
A. Functional Description (Fig. 2)
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
C814 FWD CARGO DOOR (P14) FORWARD CARGO DOOR SCHEMATIC
Cargo Door Schematics
Figure 2 (Sheet 1)
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. FORWARD CARGO DOORS WITHOUT ú
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LATCH OPEN SWITCH ú ú 06 Page 7 ú Feb 10/92
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
Cargo Door Schematics
Figure 2 (Sheet 2)
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. AFT CARGO DOORS WITHOUT ú 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(179)
