(4)
Bleed air valve opening rate test
B. The APU does not require any adjustments other than those specified as an integral part of the APU operational test. Procedures for operating the APU are given in AMM 49-11-0/201. You must do the APU operation test - LOADED CONDITION after you replace the APU, fuel control unit or bleed air valve. It is not necessary to do the cracking pressure test for the acceleration limiter valve or governor speed setting test under a NO LOAD condition for the fuel control unit after you replace the APU, fuel control unit or bleed air valve. It is not necessary to do the opening rate test for the bleed air valve after you replace the APU, fuel control unit or bleed air valve. You can use these tests for troubleshooting or adjustments of the fuel control unit or bleed air valve.
C. 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.
2. APU Operational Test
A. Equipment and Materials
(1)
0-100 pressure gage and appropriate fittings, or Pressure Gage and Case Set -No. 282645, AlliedSignal, Inc., Airline Services Division, P.O. Box 52170, Phoenix, AZ 85072-2170
(2)
RPM Indicator and Tachometer-Generator Test Set - F72891-20
(3)
FUEL CONTROL UNIT WITHOUT THE TIMED ACCELERATION CONTROL; Screwdriver and Wrench Assembly - No. 280353, AlliedSignal, Inc.
(4)
FUEL CONTROL UNIT WITH THE TIMED ACCELERATION CONTROL; Jamnut Wrench - No. 833275-1, AlliedSignal, Inc.
(5)
FUEL CONTROL UNIT WITH THE TIMED ACCELERATION CONTROL; Adjuster Wrench - No. 833274-1, AlliedSignal, Inc.
(6)
High pressure hose - 1/4 inch ID - commercially available
5C8
Aug 01/95 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 49-11-0 Page 501
B. Test APU Operation - LOADED CONDITION
(1)
Operate APU (AMM 49-11-0/201).
CAUTION: TO AVOID DAMAGING APU, OBSERVE OPERATING LIMITS (AMM\49-11-0/201).
(2)
With "no load" applied, engine speed should stabilize at 405-410 CPS as indicated on generator frequency meter.
(3)
Position air conditioning L PACK and R PACK valve switches to ON.
(4)
Make sure the engines 1 and/or 2 BLEED switches on the P5 forward overhead panel are in the OFF position.
(5)
Check that ISOLATION VALVE is in AUTO position.
(6)
On forward overhead panel, position APU BLEED AIR valve switch to ON.
(7)
Observe engine frequency on frequency meter at load application.
(8)
Move air conditioning control cabin temperature selector to MANUAL COLD until air mix valves indicate COLD.
(9)
Observe engine speed at full bleed load operation on frequency meter. Stabilized generator frequency under load should not be more than 10 CPS below that observed in (2).
(10)
Incrementally add 60 amps additional electrical load to APU generator.
(11)
Observe engine exhaust gas temperature on indicator at full bleed air load operation ("loaded" condition). This temperature is controlled by APU (load) control thermostat and should stabilize between 620°C and 650°C.
(12)
If EGT in step (11) was not met, adjust or shim control thermostat (AMM 49-52-32/501).
(13)
Remove electrical load (as required).
(14)
Position air conditioning R PACK and L PACK valve switches to OFF.
(15)
Position APU BLEED AIR valve switch to OFF.
(16)
Allow engine to operate at "no load" governed frequency for one minute (minimum).
(17)
Position APU master switch to OFF.
C. Fuel Control Unit Acceleration Limiter Valve Cracking Pressure (Opening) Test.
NOTE: It is not necessary to do the cracking pressure (opening) test for the acceleration limiter valve on the fuel control unit after you replace the APU, fuel control unit or bleed air valve. You can use this test for troubleshooting or cracking pressure (opening) adjustment of the fuel control unit.
Prior to performing fuel control unit acceleration limiter valve cracking pressure (opening) test, operate APU at "no-load" condition for approximately 5 minutes. This will ensure that fuel is available to the APU, and, if the fuel control unit was changed, will remove preservative oil from the fuel control unit.
584
49-11-0 Page 502 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Feb 20/94
(1)
Prepare for fuel control unit acceleration limiter valve cracking pressure (opening) test (Fig. 501).
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