(a)  
No oil pressure reading within 10 seconds.

NOTE:  With tester LOAD switch (29, Fig. 502) OFF, low oil pressure automatic shutdown and GENERATOR OFF BUS indication circuits are disabled.

(b)  
Ignition failure (flameout).

(c)  
Engine oil pressure exceeds limit.

(d)  
Engine exhaust gas temperature exceeds limits (Ref APU Power Plant - Maintenance Practices, Operate APU).

(e)  
Engine speed exceeds operating limits (Ref APU Power Plant - Maintenance Practices, Operate APU).

(f)  
Failure of electronic speed 50% switch to actuate at approximately 50% indicated engine speed.

503 
Feb 20/94  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  49-21-01 Page 501 

NOTE:  In event no tachometer-generator signal is received by electronic speed switch (on airplanes with electronic speed switch having starter overspeed protection), an automatic shutdown will occur approximately 11-15 seconds following starter engagement.

G00064
APU Air Inlet Screen  502 
49-21-01Page 502   Figure 501 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Feb 20/85 

2.  APU Power Plant Test
A.  Engine Start, Acceleration, Operation, and Automatic Controls Test
NOTE:  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.
(1)  
Equipment and Materials

(a)  
Gas Turbine Engine Tester - No. 290270-2-1, AlliedSignal, Inc., Airline Services Division, P.O. Box 52170, Phoenix, AZ 85072-2170

(b)  
Electrical Cable Assembly - No. 834367-1, AlliedSignal, Inc.

(c)  
Test Cable Assembly - No. 294110-1, AlliedSignal, Inc. (this is an alternative to the 834367-1 Electrical Cable Assembly)

(d)  
Adapter Cable Assembly - No. 2024498-1, AlliedSignal, Inc. (this is an alternative to the 834367-1 Electrical Cable Assembly)

(e)  
Wheatstone Bridge - capable of measuring resistance of 8 ohms (+0.05 %), Model 1432U, General Radio Co., W. Concord, MA

(f)  
Multimeter - measurement range of 8 ohms (+0.05%), Model 8012A-01, Fluke, P.O. Box 9090, Everett, WA 98206-9090 (this is an alternative to the wheatstone bridge).

(2)
Prepare for Engine Start, Acceleration, Operation, and Automatic Controls Test

(a)  
Position BATTERY SWITCH to OFF and placard.

(b)  
Open APU compartment access door latches and open access door. Install door support rods.

(c)  
Support shroud, open shroud latches, and remove shroud.

CAUTION:  EXERCISE EXTREME CARE NOT TO DAMAGE SHROUD DRAIN LINES WHEN HANDLING SHROUD.
(3)  Connect gas turbine engine tester to engine (Fig. 502).
(a)  
Disconnect APU harness (47) electrical plug (D1252) from receptacle (D452) in upper shroud.

(b)  
Connect the electrical cable or test cable assembly (46) to the electrical connector D1252 and the receptacle D452.

NOTE:  The connectors on the electrical cable assembly are identified by aluminum markers.

(c)  
Disconnect the leads of the thermocouple harness from the terminals of the EGT thermocouple probe.

(d)  
Connect the leads of the electrical cable or test cable assembly (46) to the terminals of the EGT thermocouple probe.

(e)  
Connect the electrical cable or test cable assembly (46) to the tester receptacle (13).

(f)  
Disconnect plug D1245 (45) from electronic speed switch (44) located in aft passenger cabin adjacent to flight recorder.

(g)  
Connect the electrical cable or test cable assembly (46) to electronic speed switch receptacle (44) and to mating electrical plugs (45).

Feb 01/95  49-21-01
Page 503
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

E67335 E67623
Gas Turbine Engine Tester and Connections  563 
49-21-01  Figure 502 (Sheet 1)  Feb 01/95 
Page 504 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

563  Gas Turbine Engine Tester and Connections 
Feb 01/95  Figure 502 (Sheet 2)  49-21-01 
Page 505 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

(h)  At initial use of tester, check tester exhaust gas temperature loop resistance as follows: 1) Remove tester instrument panel attaching screws and lift panel to obtain
　
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