737 AMM 飞机维护手册 机载辅助动力AIRBORNE AUXILIARY POWER(48)

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5.  Operation
A.  Static or ram air is drawn in the first stage impeller from the compressor plenum. Following compression in the first stage impeller and diffuser, the air is guided to the compressor second stage through the crossover ducts. The air is further compressed by the second stage impeller and diffuser and collected in the turbine plenum. Part of the air flows to the combustion chamber; the remainder is available for the bleed air pneumatic power. Fuel is injected into the combustion chamber by a fuel atomizer. The air-fuel mixture is ignited by an igniter plug. No ignition is required for sustained combustion. From the combustion chamber, the hot combustion gases flow through the turbine torus where a series of nozzles direct them against the blades of the turbine wheel and rotate the wheel. Thus, the turbine wheel converts the energy of combustion gases into useful mechanical power. Part of this power is used to drive the compressor and the engine accessories; the remainder is available as shaft power to drive the ac electrical generator. The cooler, low pressure exhaust gases are discharged from the engine through the exhaust port.
500 
49-21-0 Page 2  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Aug 15/67 

G00101
500  APU Engine 
May 15/68  Figure 1  49-21-0 
Page 3 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

APU ENGINE - MAINTENANCE PRACTICES
1. General
A.  This procedure gives the steps to manually turn the APU. To manually turn the APU you must remove the starter motor. You can then turn the APU by using a socket on the starter jaw pawl nut.
2.  Manually Turn the APU (Fig. 201)
A.  References
(1)  AMM 49-41-11/401, Starter Motor
B.  Equipment
(1)  3/8 inch socket on 1/4 inch drive wrench
C.  Procedure
(1)  Remove the starter motor (AMM 49-41-11/401)
(a)  Install 3/8 inch socket onto starter drive pawl nut. Turn socket clockwise with 1/4 inch drive wrench.
NOTE: When you turn the shaft for the starter motor clockwise, the APU will turn.
(2)  Install the starter motor (AMM 49-41-11/401)
501 
Aug 01/96  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  49-21-0 Page 201 

F95948
Location to Manually Turn APU  501 
49-21-0  Figure 201  Aug 01/96 
Page 202 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

APU ENGINE - ADJUSTMENT/TEST
1.  General
A.  The APU power plant does not require specific adjustments. Any adjustments that may be required are performed during the power plant test. The test consists of four parts: engine start, acceleration, operation, and automatic controls test; fuel control unit governor speed setting test; fuel control unit acceleration limiter valve test; and APU bleed air valve test. Each test is independent from others and may be performed after an engine component replacement or when a certain component is suspected of malfunctioning, such as adjusting the governor when ac electrical generator frequency is not 400 Hz.
B.  It is not necessary to do the APU engine start, acceleration, operation, and automatic controls test after you replace the APU, fuel control unit or bleed air valve. You can use this test for troubleshooting the oil pressure problems of the APU. In addition, this test may be used when any of the following components are replaced: electronic speed switch, sequencing oil pressure switch, low oil pressure switch, fuel solenoid valve, and oil pump. Replacement components such as starter motor, igniter plug, ignition unit, and combustion chamber and atomizer assembly may be tested during engine run-up as described in AMM 49-11-0/201.
C.  Operating Limits
(1)  Design parameters and operating characteristics determine operating limits of the engine. If the limits listed in AMM 49-11-0/201 are exceeded, the engine must be shut down immediately and the malfunction corrected.
D.  Engine Operating Precautionary Requirements
(1)  
To preclude APU ingestion of foreign objects while airplane cabin area is being serviced and aft galley door is open, it is recommended that APU inlet screen, (Fig. 501), be installed before starting APU. If APU is operating and the aft galley door is going to be opened for servicing, the APU must be shut down and the inlet screen installed before galley door is opened and APU restarted. Do not remove screen until APU operation is complete and aft galley door is closed.

(2)  
Shut down engine at once and correct malfunction if any of the following conditions occur:
　
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