EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 52-31-00
 ALL  ú ú 02 Page 10 ú Feb 10/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 (3)  
Allow four minutes cooling before closing door to prevent overheating of the drive unit motor. To close the nose cargo door, simutaneously hold the SYSTEM POWER in the ON position and the DOOR CONTROL switch in the CLOSE position to supply electrical power to all actuators in reverse order of the opening operation. When the drive unit lowers the door to approximately 1.3 inches from fully closed, a limit switch within the drive unit stops the drive unit motor and allows current to flow to the push-pull cam actuator. Through cam engagement with rollers the door is pulled against the seal and actuates a sequence switch within the actuator that stops the motor and provides current flow to the 16 latch actuators.

 (4)  
The door movement can be stopped at any time during the opening or closing position by releasing either the SYSTEM POWER or the DOOR CONTROL switch. The door will then stop and remain in that position.

 B.
Control

 (1)  
The following describes operation of the door with the normal electrical controls. For manual operation of the door in the event electrical operation is not possible (AMM 52-31-00).

 (2)  
Prepare to open or close nose cargo door.

 (a)  
Provide electrical power (AMM 24-22-00/201).

 (b)  
Check that the following circuit breakers on main deck ground handling bus of right main power center panel P15 are closed: 1) NOSE CARGO DOOR (115V AC) 2) NOSE CARGO DOOR CONT (28V DC)

 (c)  
Check that the following circuit breakers in nose door control equipment module H122 are closed: 1) LATCHES 5-8 LEFT 2) LATCHES 1-4 LEFT 3) LATCHES 1-4 RIGHT 4) LATCHES 5-8 RIGHT 5) PULL UP CAM 6) DOOR LIFT

 (3)  
Open nose cargo door.

 (a)  
Simultaneously hold SYSTEM POWER switch in the ON position and DOOR CONTROL switch in the OPEN position. When door is fully open, the blue DOOR UP light on the H121 panel will be illuminated.

 NOTE: Door motion can be stopped at any point by
____
 releasing switch.

 NOTE: When the door opens or closes it can make unusual noise
____ when the latch pins engage the spherical bearings.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 52-31-00
 ALL  ú ú 02 Page 11 ú Feb 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 (b)  
Install safety barrier across door opening if door will be left open with personnel aboard.

 (4)  
Close nose cargo door.

 (a)  
Remove nose cargo door safety barrier, if installed.

 WARNING: CHECK THAT PERSONNEL AND EQUIPMENT ARE CLEAR OF DOOR PATH.
_______ SERIOUS INJURY TO PERSONNEL OR EQUIPMENT CAN OCCUR.
 (b)  Simultaneously hold SYSTEM POWER switch in the ON position and DOOR CONTROL switch in the CLOSED position. Door is fully closed when the green LATCHES CLOSED light on the H121 panel is illuminated and all green lights on the NOSE CARGO DOOR LATCH ANNUNCIATOR module are illuminated.
 NOTE: Door motion can be stopped at any point by releasing
____
 either switch.

 NOTE: When the door opens or closes it can make unusual noise
____ when the latch pins engage the spherical bearings.
 (c)  Hold the SYSTEM POWER switch in the OFF/LOCK TEST position and make sure the the green LOCK OUT ENGAGED light on the H121 panel comes on.
 NOTE: The door is locked when the green LOCK OUT ENGAGED light
____ comes on while holding the SYSTEM POWER switch to the OFF/LOCK TEST position.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 52-31-00
 ALL  ú ú 02 Page 12 ú Oct 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
　
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