32-21-09
 ALL  ú ú 01 Page 405 ú Oct 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 S 644-025
 (3)  
Apply a layer of grease around the axle on the surfaces which will engage with the axle sleeve (Fig. 401).

 (a)  
Do not remove the grease from the outer edge of the axle recess (Fig. 401).

 S 094-026
 (4)  
Remove the electrical heat blanket from the axle sleeve.

 S 424-027

 (5)  
Immediately install the axle sleeve before the temperatures of the sleeve and the axle go to the ambient temperature.

 CAUTION:_______DO NOT HIT THE SLEEVE DIRECTLY WITH THE HAMMER. THIS WILL CAUSE DAMAGE TO THE AXLE SLEEVE.
 (a)  
If it is necessary, carefully use a hammer with a block of wood to move the sleeve.

 (b)  
Make sure a minimum clearance of 0.120 inch (3.048 millimeter) is between the flat edges of the saw clearance (Fig. 401).

 (c)  
If the axle sleeve goes too far on the axle, use the axle sleeve puller to put the sleeve in its correct position.

 NOTE: The electrical heat blanket and the dry ice will help
____ with the movement of the sleeve.
 S 434-042
 (6)  
Install the tire/wheel assembly (AMM 32-45-02/401).

 G.
Put the Airplane in Its Usual Condition

 S 094-043
 WARNING: YOU MUST CAREFULLY DO THE STEPS IN THE TASKS BELOW TO REMOVE
_______ THE DOOR LOCKS FROM THE LANDING GEAR DOORS. THE DOORS CAN CLOSE QUICKLY IF YOU DO NOT REMOVE THE DOOR LOCKS CORRECTLY. THIS CAN CAUSE INJURY TO PERSONS OR DAMAGE TO EQUIPMENT.
 (1)  
Do this task: "Removal of the Door Locks from the Nose Landing Gear" (AMM 32-00-30/201).

 S 094-044

 (2)  
Do this task: "Removal of the Door Locks from the Wing and Body Landing Gear" (AMM 32-00-30/201).

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 32-21-09
 ALL  ú ú 01 Page 406 ú Oct 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
 1.

2.

3.

4.

A
747-400 MAINTENANCE MANUAL
 NOSE GEAR DOORS - DESCRIPTION AND OPERATION
___________________________________________
General (Fig. 1)
_______
 A.  The nose gear doors are clamshell type and consist of four doors that fair with the fuselage contour when closed. All doors are of alclad rib and skin construction.
Forward Nose Wheel Well Doors and Mechanism (Fig. 2)
___________________________________________
 A.  The two forward nose wheel well doors are hydraulically actuated by a bellcrank. Each door is attached to the wheel well outer edge by three hinges. Each door forward end has a fitting to which a rod from the bellcrank is attached to operate the doors. These doors are normally open only when the gear is in transit. They may be manually opened for ground maintenance. A small flapper door is hinged at the aft end of each forward door to provide clearance for the drag strut when the gear is extended.
Aft Wheel Well Doors and Mechanism (Fig. 2)
__________________________________
 A.  The two aft wheel well doors are mechanically actuated by a bellcrank slaved to the nose gear. Each door is attached to the wheel well outer edge by two hinges. Each door forward upper corner has a fitting to which is attached a rod from the bellcrank for door operation. These doors remain open while the nose gear is down.
Ground Door Release Handle
__________________________
 A.  The ground door release handle is located outside the fuselage above the left nose landing gear shock strut door hinge.
 WARNING: RAPID ACTION OF DOORS MAY INJURE PERSONNEL OR CAUSE DAMAGE.
_______ OBSERVE THAT GROUND DOOR RELEASE HANDLE IS IN DOORS OPEN POSITION AND LATCHED BEFORE ENTERING WHEEL WELL WITH FORWARD DOORS OPEN.
 B.  The ground door release handle is used to open the wheel well forward doors to permit entrance to the wheel well for installing the nose gear door ground lock and performing certain maintenance and inspection procedures in the nose gear wheel well area.
 C.  Operation of the ground door release handle to the DOORS OPEN and latched position drives the nose gear door safety valve to "pressure dumped" position and unlocks the door actuator locks. The weight of the doors then causes the doors to open. The door safety valve and the door lock actuation mechanism are the same ones used for emergency extension.
　
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