24-23-00
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 GENERATOR AND BUS CONTROL UNITS - REMOVAL/INSTALLATION
______________________________________________________
 1.  General_______
 A.  This procedure has two tasks. One task is the removal of the generator control unit (GCU) (G6, G7, G8, and G9) or the bus control unit (BCU) (G10 and G11). The other task is the installation of the unit.
 B.  The removal task includes an check for shop failures that are kept in the CMCS.
 C.  The installation task includes an operational test of the units.
 D.  The GCUs and BCUs are installed on the top shelf of the E/E rack in the E/E compartment. Access to the E/E compartment is through the door behind the nose wheel or through the forward cargo compartment.
 TASK 24-23-01-004-001
 2.  Generator and Bus Control Unit Removal (Fig. 401)______________________________________
 A.  References
 (1)  
AMM 20-11-22/401, Rack-Mounted Electrical/Electronic Module

 (2)  
AMM 24-22-00/201, Manual Control

 (3)  
AMM 45-10-00/201, Central Maintenance Computer System

 (4)  
AIPC 24-23-01, Fig. 20

 (5)  
AIPC 24-23-01, Fig. 30

 (6)  
WDM 24-11-11 thru WDM 24-11-14, WDM 24-21-12, WDM 24-21-22, WDM 24-21-32, WDM 24-21-42, WDM 24-22-11 thru WDM 24-22-74, WDM 24-23-11 thru WDM 24-23-22, WDM 24-27-51 thru WDM 24-27-52, WDM 24-41-12 thru WDM 24-41-23

 (7)  
SSM 24-11-01 thru SSM 24-11-04, SSM 24-21-01 thru SSM 24-21-04, SSM 24-22-01 thru SSM 24-22-07, SSM 24-23-01 thru SSM 24-23-02, SSM 24-23-04, SSM 24-27-01 thru SSM 24-27-07, SSM 24-32-02, SSM 24-34-01 thru SSM 24-34-03, SSM 24-41-01 thru SSM 24-41-02

 B.  
Access

 (1)  
Location Zone 117 Electrical and Electronics Compartment, LH 118 Electrical and Electronics Compartment, RH

 C.  
Shop Failure Check (Optional)

 (1)  
Supply electrical power (AMM 24-22-00/201).

 S 864-009
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400
MAINTENANCE MANUAL

SEE  A  GCU NO. 3 
GCU NO. 4  (G8) 
(G9)  SEE  B 
SEE  B 
BCU NO. 2  GCU NO. 2
(G11)  (G7) 
SEE  C  SEE  B 
BCU NO. 1 
(G10) 
SEE  C  GCU NO. 1 
(G6) 
SEE  B 

ELECTRICAL AND ELECTRONICS RACK A
GCU BCU
(TYPICAL) (TYPICAL)
B C
Generator Control Unit (GCU) and Bus Control Unit (BCU) Installation Figure 401
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 ALL  ú ú 01 Page 402 ú Dec 10/88
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400 MAINTENANCE MANUAL
 S 284-018
 (2)  
Do a check for shop failures of the GCU or the BCU.

 (a)  
Push the MENU key on the CDU to show the MENU.

 (b)  
Push the LSK adjacent to the <CMC prompt to show the CMC MENU.

 (c)  
Push the LSK adjacent to the <SHOP FAULTS prompt to show the SHOP FAULTS menu.

 (d)  
Push the NEXT PAGE key until you find the <24 ELECTRICAL POWER prompt.

 (e)  
Push the LSK adjacent to the <24 ELECTRICAL POWER prompt to show the SHOP FAULTS menu for the electrical system.

 (f)  
Push the NEXT PAGE key until you find the applicable <BCU or <GCU prompt.

 (g)  
Push the LSK adjacent to the applicable <BCU or <GCU prompt.

 (h)  
Make a note of all the shop failures shown.

 S 864-011
 (3)  Remove electrical power (AMM 24-22-00/201).
 NOTE: If you want to keep airplane power available during a GCU
　
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