CAUTION:  THERE IS A CHECK BALL AND SPRING BEHIND THE RETAINING PLUG. DO NOT COMPLETELY REMOVE THE SPRING RETAINING PLUG FOR THE PURGE PROCEDURE, ONLY LOOSEN IT ONE TURN. IF THE SPRING RETAINING PLUG IS COMPLETELY REMOVED FOR THE PURGE PROCEDURE, THE CHECK BALL AND SPRING WILL BE LOST. THE RESULT WILL BE HOT STARTS AND REDUCED APU HOT SECTION LIFE.
D.  Purge TAFCU
(1)  
On TAFCU with priming valve, a second person will be required to push and hold the priming valve during the motoring procedure.

(2)  
Position No. 1 tank forward boost pump to ON.

NOTE:  No. 1 tank boost pump requires ac power.  If you must use the fuel boost pumps in the center tank, you must have a maintenance person or observer in the flight compartment to continuously monitor the LOW PRESSURE lights.  Turn the applicable fuel boost pump to the OFF position if the LOW PRESSURE light for the center tank stays on.

(3)  
Remove placard and position BATTERY switch power.

(4)  
Motor APU for 90 seconds (par. 3.D.).

E.  Restore Airplane to Normal Configuration
(1)  
Position No. 1 tank forward boost pump switch and BATTERY SWITCH to OFF and placard.

(2)  
Connect ignition unit power supply electrical plug to ignition unit.

(3)  
Position lower shroud against upper shroud and close shroud latches.

CAUTION:  MAINTAIN A MINIMUM CLEARANCE OF 0.18 INCH BETWEEN ENGINE PLUMBING, FIRE DETECTOR, CLAMPS AND INSIDE SURFACE OF LOWER SHROUD.
EXERCISE EXTREME CARE NOT TO DAMAGE SHROUD DRAIN LINES WHEN HANDLING SHROUD.
(4)  
Disengage APU compartment access door support rods and stow rods. Close and latch access door.

(5) 
 Remove placard.

Sep 01/02 49-11-0 Page 219 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

H35638
Fuel Control Unit Installation  500 
49-11-0 Page 220  Figure 401 (Sheet 3) BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  May 01/98 

APU POWER PLANT - REMOVAL/INSTALLATION
1. General

A.  This section covers removal/installation of the APU power plant, consisting of the APU engine, ac electrical generator, and engine mount brackets. The procedure given is for removal of the APU power plant and installation of a replacement unit. However, the same procedure can be used for maintenance of power plant. The unit may be lowered on an aero stand for replacement of the engine mount brackets or the ac electrical generator. Access to the ac electrical generator is gained simply by removing lower shroud, but due to the weight of the generator and space limitations, replacement of the generator is simplified if the APU power plant is lowered as described above.
2.  Equipment and Materials
A.  Hoisting Cradle Assembly - F80002, or F80114-1 (preferred)
B.  Two Fishpole Hoist Assemblies - F80039-1, or PF51-003 (preferred, PF Industries 9320 15th South, Seattle, Washington 98108). Alternate Fishpole Hoist Assemblies, (10/3641 Hoist -Fishpole, Manual Powered (Quantity of 3) Didsbury Engineering Co. Ltd, Manor Road, Levenshulme, Manchester M19 3EJ).
C.  Transportation Dolly - F72950-2 superseded by F72950-127 or F72950-138 (for future procurement)
3.  Prepare to Remove APU Power Plant
A.  Open the following circuit breakers on circuit breaker panel P6.
(1)  
Fire DETECTION APU

(2)  
APU GENERATOR CONTROL

(3)  
APU CONT

(4)  
HOT BAT, BAT BUS CONT

(5)  
HOT BAT, GEN CONT

(6)  
HOT BAT BUS

B. Open the circuit breaker on M280 module -APU accessory unit on E3-3 electronic shelf.
500 
May 01/03  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  49-11-0 Page 401 

C.  Position BATTERY SWITCH and APU START SWITCH to OFF and placard that APU maintenance is “in work.”
D.  Open APU compartment access door latches and open door. Install door support rods.
E.  Support lower shroud, open shroud latches, and remove shroud.
CAUTION:  EXERCISE EXTREME CARE NOT TO DAMAGE SHROUD DRAIN LINES WHEN HANDLING SHROUD.
4.  Remove APU Power Plant
A.  Disconnect APU harness, APU starter motor, and APU generator plugs from receptacles in upper shroud.
B.  Disconnect APU generator control plug from receptacle in upper shroud.
C.  Disconnect EGT indicating system plug from receptacle in upper shroud.
D.  Disconnect bleed load control air line from fitting in upper shroud.
E.  Disconnect fuel hose from elbow on low-pressure fuel filter (View 1, Fig. 401). Catch dripping fuel in a suitable container.
　
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