49-11-01
 ALL  ú ú 04 Page 428 ú Jun 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 2) APU DOOR
 3) APU STRT INHIBIT

 S 214-122
 (4)  
Do a visual check of the two EGT bus bars:

 (a)  
Make sure the two EGT bus bars do not touch each other and are not damaged.

 (b)  
Make sure there are no unwanted metal parts on the two EGT bus bars.

 (c)  
If you find damage, the two EGT bus bars touch each other or there are unwanted metal parts on the two EGT bus bars, repair or replace the positive (KP) and/or negative (KN) bus bar(s).

 I.
Put the Airplane Back to Its Usual Condition

 S 414-121
 (1)  
Close the left APU access door, 317AL, and right APU access door, 318AR:

 (a)  
Remove the two quick-release pins, disconnect the two hold-open rods and put the two hold-open rods in the two clips on the right access door.

 (b)  
Install the two quick-release pins in the two brackets on the right APU compartment bulkhead.

 (c)  
Lift the right access door until you can install the lanyard on the pin at the aft APU compartment bulkhead.

 NOTE: The lanyard will hold the right access door on the APU
____
 compartment bulkhead.

 (d)  
Remove the two quick-release pins, disconnect the two hold-open rods and put the two hold-open rods in the two clips on the left access door.

 (e)  
Install the two quick-release pins in the two brackets on the left APU compartment bulkhead.

 (f)  
Make sure the insulation covers are correctly attach to the APU compartment firewall.

 (g)  
Lift the left access door until the two APU access doors are approximately aligned.

 (h)  
Close the two APU access doors.

 (i)  
Close the six latches on the right access door.

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 49-11-01
 ALL  ú ú 04 Page 429 ú Jun 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
 1.
2.

3.

4.

A
747-400 MAINTENANCE MANUAL
 APU MOUNTS - DESCRIPTION AND OPERATION
______________________________________
General (Fig. 1)
_______
 A.  The APU mounts support the APU installation and isolate the airplane structure from adverse vibrations of the APU. The APU is supported by two forward mounts and one aft mount. Both forward mounts support the APU vertically and axially. In addition, the left forward mount supports the APU laterally. The aft mount supports the APU vertically and laterally.
Forward Mounts (Fig. 1)
______________
 A.  The forward mounts attach the APU to the airplane vertical firewall, located forward of the APU. The forward mounts consist of tubular supports, shockmounts, and brackets. Cone bolts are integral with the shockmounts. The brackets are installed on the APU. The left shockmount is attached to fittings on the firewall through three supports and is rigid. The right shockmount is attached to fittings on the firewall through two supports. The supports are designed to swing slightly laterally from the firewall attach points to provide for thermal expansion of the APU. When the APU is installed in the airplane, the cone bolts are secured to brackets with nuts.
Aft Mount (Fig. 1)
_________
 A.  The aft mount attaches the APU to airplane upper structure. It consists of a vertical support tube, beam, shockmount, support block for the cone bolt, and links. The cone bolt is integral with the shockmount. The support block is installed on the APU with two links. The links are designed to provide for axial and radial thermal expansion of the APU. The beam is permanently attached to the airplane. The shockmount is installed at the midpoint of the beam. In addition, the shockmount is attached to a fitting on the airplane upper structure through a vertical support tube. The cone bolt is secured to the support block with a nut.
Shockmount (Fig. 1)
__________
 A.  The shockmount prevents APU vibrations from being transmitted to the fuselage. The shockmount consists of resilient material bonded to the cone bolt and is enclosed in a housing. As the APU vibrates, the resilient material slightly deforms to absorb and dampen the APU vibrations.
　
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