52-34-24
 ALL  ú ú 01 Page 409 ú Jun 18/99
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 214-068
 CAUTION:_______ IN CASE THE DOOR DOES NOT OPEN, STOP IMMEDIATELY.  DO NOT
 OPERATE THE DOOR CONTROL SWITCH.  HOLDING THE DOOR CONTROL
 SWITCH MAY DAMAGE THE ACTUATOR.  WAIT AT LEAST 1 MINUTE BEFORE
 SECOND ATTEMPT.  IF THE DOOR STILL DOES NOT OPEN, WAIT AT LEAST

 10 MINUTES BEFORE THIRD ATTEMPT.
 (8)  
Open and close the door electrically and make sure that the pull-in hook properly engages with the hook pin.

 S 424-065

 (9)  
Reinstall the maintenance access panels as required.

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 52-34-24
 ALL  ú ú 01 Page 410 ú Jun 15/98
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 BULK CARGO DOOR - DESCRIPTION AND OPERATION
___________________________________________
 1.  General_______
 A.  The bulk cargo door is located on the aft lower right side of the fuselage with its centerline at station 2007. It is an inward opening door, cantilever hinged at its upper edge, and operated manually from either inside or outside the airplane. It is a plug-type door and carries pressure loads only.
 2.  Door (Fig. 1)____
 A.  The bulk cargo door is an alclad structure with outer and inner skin and internal webs and stiffeners.
 B.  The door is hinged from the fuselage structure by two hinge arms on its upper edge. It is equipped with centering devices (Detail C). Two rollers center the door in the closed position by engaging a centering plate on the fwd and aft door jambs.
 C.  Pressurization loads on door are transmitted to the fuselage by sixteen adjustable stop fittings attached to the forward, aft, and lower edge of the door, which bear against corresponding stop pads attached to the fuselage structure surrounding the door (Detail D). Loads on the upper edge of the door are transmitted to the fuselage structure by the two hinge arms. A continuous sealing strip prevents loss of cabin pressure around the door edges when the airplane is in flight (Detail D).
 D.  The door is equipped with a balance mechanism which counterbalances its weight and thus facilitates door opening. A positive mechanical latch on the station 2000 floor beam secures the door in the fully open position if required (Detail B). The door is included in the door warning system. A snubber between the door and structure slows closing descent of the door.
 E.  The door latching mechanism consists of two internal horizontal rod assemblies at each end of which a probe latch with a latching roller protrudes beyond the edge of the door (Detail E). These latching rollers engage latch fittings attached to the fuselage structure. The rod assemblies in the door are connected to the operating handle assembly which consists of a short shaft passing through the thickness of the door with an operating handle at each end. The handle on the inboard side of the door projects beyond the inboard skin, but the outboard handle is spring loaded so that it retracts flush with the exterior surface when it is released after use. A recessed finger access pan adjacent to the handle provides access for the fingers when the handle is to be used.
 F.  Two access panels in the outer skin provide external access to the door latching mechanism to open the door in the event of failure of the latching mechanism.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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 ALL  ú ú 01 Page 1 ú Feb 10/89
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

SEE A
HINGE ARM
SNUBBER
INSULATION
HINGE ARM BOLT (8 LOCATIONS)
BALANCE MECHANISMCABLE DRUM
BALANCE 
　
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