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 49-15-00
 ALL  ú ú 01 Page 2 ú Mar 15/92
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
4.  Air Inlet Door Actuator (Fig. 1)
_______________________
 A.  The inlet door actuator opens and closes the air inlet door with a rotary type mechanism. This mechanism has a gear train and a worm gear. The inlet door actuator is in a housing. Two output shafts are a part of the worm gear. Two actuator arms operate the pushrods and attach to the output shafts of the actuator. The inlet door actuator is energized by a dc motor that has a magnetic brake. The APU master switch starts the dc motor operation. The dc motor operation is stopped by one of the two limit switches in the inlet door actuator. One limit switch controls the opening cycle and the other limit switch controls the closing cycle. Located inside of the fuselage, the inlet door actuator is aft of the rear pressure bulkhead.
 5.  Operation
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 A.  When the APU master switch is moved to the START position, the APU control unit transmits a 28V dc signal through the ON position of the APU master switch. This 28V dc signal goes to the APU fuel valve and through the APU control unit. The 28V dc signal energizes the open coil for the APU fuel valve and opens the APU fuel valve. When the APU fuel valve is opened, the 28V dc signal energizes the open coil for the inlet door actuator and opens the air inlet door. After the air inlet door opens, the APU engine will start.
 B.  If the air inlet door does not fully open, a 28V dc signal from the APU control unit moves through the door open switch for the air inlet door. This 28V dc signal returns to the APU control unit and energizes the K1 start-stop relay. The APU will not start.
 C.  When the APU master switch is moved to the OFF position, the APU control unit transmits a 28V dc signal through the OFF position of the APU master switch. This 28V dc signal goes to the APU fuel valve, through the APU control unit. The 28V dc signal energizes the close coil for the APU fuel valve and closes the APU fuel valve. When the APU fuel valve is closed, the APU engine stops and the 28V dc signal energizes the close coil for the inlet door actuator. The air inlet door closes.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 49-15-00
 ALL  ú ú 01 Page 3 ú Jul 15/92
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
APU AIR INLET - ADJUSTMENT/TEST
_______________________________
 1.  General
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 A.  This procedure gives the tasks to do the adjustments and a test of the air inlet system for the APU. The adjustments and the test make sure that the air inlet system aligns correctly and operates correctly. The pushrods for the air inlet door, air inlet door switch plunger (which is referred to in this procedure as the door switch plunger) and vortex generator flap must operate smoothly.
 B.  The door switch plunger and vortex generator must be adjusted each time the position of the air inlet door changes. The position of the air inlet door changes when you remove it or align it again. The test does a check of the air inlet door. The installation properties of the air inlet door switch (which is referred to in this procedure as the door switch) do not permit a test of the door switch plunger.
 TASK 49-15-00-205-001
 2.  Air Inlet Door Adjustment (Fig. 501)
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 A.  Access
 (1)  
Location Zones
 101 Control Cabin (Left)
 701 Tail Compartment

 (2)  
Access Panels
 3701 Stabilizer Trim Access Door

 B.  Procedure
 S 865-002
 (1)  
Set these switches on the P5 forward overhead panel:

 (a)  
Set the BAT switch to the ON position.

 (b)  
Set the APU master switch to the ON position and attach a DO-NOT-OPERATE tag.

 (c)  
After the air inlet door opens, put the BAT switch to the OFF position and attach a DO-NOT-OPERATE tag.
　
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