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 4.  Track Assembly______________(Fig. 3)
 A.  The upper deck door upper track and lower track are extruded members located above and below the door opening on the inside of the fuselage. The tracks incorporate upper and lower contact surfaces to accommodate the carriage V-type wheels. The tracks are supported by clips attached to the outboard side of the track and to fuselage frames. An I-section strut connected to the aft end of the lower track distributes loads incurred during door stowage. The upper and lower carriage assemblies traverse on their respective tracks during fore and aft movement of the door. Snubbers are installed at each end of the tracks for carriage stops to prevent damage to the door or adjacent structure. A door latch mechanism, comprised of a manual handle, torque shaft, pushrod, spring cartridge, and a stop latch, is installed at the aft end of the upper track to latch the door in the stowed position against the aft snubbers.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
UPPER TRACK
ASSEMBLY

SEE A
CARRIAGE WHEELS (4 LOCATIONS)
TORQUE SHAFT
DOOR SNUBBER PUSHROD
UPPER PIVOT FITTING
DOOR LATCH CARRIAGE
MANUAL HANDLE LOWER TRACK ASSEMBLY TRACK
ASSEMBLY STOP LATCH
SEE B
UPPER TRACK ASSEMBLY
A
DOOR
SNUBBER
CARRIAGE ASSEMBLY
CARRIAGE WHEELS
(4 LOCATIONS)

TRACK
DOOR SNUBBER
I-SECTION STRUT
LOWER TRACK ASSEMBLY
B
Track Assembly Figure 3
SPRING CARTRIDGE
TRACK SUPPORT CLIP (EXAMPLE)
DOOR SNUBBER
TRACK SUPPORT CLIP (EXAMPLE)
B41089
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 ALL  ú ú 01 Page 6 ú Oct 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 5. Operation
_________
 A. Functional Description
 (1)  
The door is opened from inside the airplane by pulling the interior handle inboard and rotating it clockwise one-half turn. As the interior handle moves inboard, the exterior handles move outboard. Initial rotation of the interior handle rotates the control cam which transmits linear movement to the inboard latching crank. The latching crank, connected by pushrod, rotates the latch torque tube. Rotation of the latch torque tube withdraws the latch rollers from the latch cams. Withdrawal of the latch rollers closes the door warning switch. After the latching crank has operated, continued rotation of the control cam transmits linear movement to the upper and lower cocking cranks. The upper cocking crank, connected by pushrod, rotates the upper hinge fitting. The lower cocking crank, connected by control rods and torque tube, rotates the lower inboard hinge fitting. As the lower inboard hinge fitting rotates, the lower outboard hinge fitting pivots about the lower inboard hinge fitting and moves the door upward and inboard. The track surfaces of the control cam are traced so that the upper cocking crank operates first to rotate the upper door edge clear of the upper sill; then the lower cocking crank operates to rotate door inboard approximately 11 inches. With door in full inboard position and resting on the door supports, the release hook engages the door latch pin bracket on the lower forward portion of the door, latching the door to the carriage. With the handles in the stowed position, the door is stowed by sliding the door aft on the carriage tracks until the hold-open latch engages the upper carriage.

 (2)  
The door is opened from outside the airplane by pulling the two exterior (butterfly) handles outward and rotating them counterclockwise one-half turn. As the exterior handles rotate counterclockwise, the interior handle rotates clockwise and the door mechanism functions as described above. External door handle rollers, moving on the housing bearing surface, serve to hold the door handles extended when rotated out of the stowed position. The exterior handle must be stowed manually before moving door aft to stowed position.

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