EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. APU WITH THE ELECTRONIC SPEED SWITCH ú
 49-00-00
 PART NUMBER 3876259  ú
 ú  02  Page 180C
 ú  Jul 12/01 

BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
L37726
////////////////////////A / GTCP85-129 SERIES /737-300/400/500/ ENGINES /MAINTENANCE MANUAL ////////////////////////
APU ENGINE FREQUENCY  PREREQUISITES 
FOR THE NO-LOAD CON- MAKE SURE THIS SYSTEM WILL OPERATE: 
DITION IS NOT BETWEEN  APU (AMM 49-11-00/201) 
405-410 CPS ON THE  MAKE SURE THE AIRPLANE IS IN THIS CONFIGURATION: 
"APU FREQ" METER  ELECTRICAL POWER IS ON (AMM 24-22-00/201) 

POSSIBLE CAUSES:
1.
FUEL CONTROL UNIT PROBLEM (AMM 49-31-11/401)

2.
P5-13 POWER MODULE FOR THE ELECTRICAL METERS, BATTERY AND GALLEY PROBLEM (WDM 24-28-11,-21).

FAULT ISOLATION:
NO
1 DO THE TEST OF THE GOVER-
NOR SPEED FOR THE FUEL CONTROL
UNIT (AMM 49-11-00/501).
DID THE GOVERNOR SPEED
ADJUST TO THE CORRECT SPEED?
YESYES
2 START AND OPERATE THE APU
(AMM 49-11-00/201).
IS THE APU ENGINE FRE-
QUENCY FOR THE NO-LOAD CONDI-
TION BETWEEN 405-410 CPS ON
THE "APU FREQ" METER?
NO NO
3 SET THE SWITCHES ON THE 53 DO THE APU USUAL SHUTDOWN
POWER TEST MODULE, M400, TO (AMM 49-11-00/201).
"B" AND "1". REPAIR THE CIRCUIT FROM
PUT THE APU ELECTRICAL THE APU ELECTRICAL GENERATORGENERATOR ON THE NO. 1 (LEFT)TO THE "FREQ" METER ON THE BUS. P5-13 POWER MODULE.
CONNECT A FREQUENCY METER TO THE "AC" TEST JACKS ON THEPOWER TEST MODULE, M400.
DOES THE FREQUENCY METER SHOW 405-410 CPS?

(AMM 49-11-00/201).
 REPLACE THE "FREQ" METER ON THE P5-13 POWER MODULE (WDM 24-28-11,-21).
APU Engine Frequency for the No-Load Condition Is Not
Between 405-410 CPS on the APU FREQ Meter
Figure 118

EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
 49-00-00
 ALL  ú
 ú  02  Page 180D
 ú  Jul 12/00 

BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / GTCP85-129 SERIES /737-300/400/500/ ENGINES /MAINTENANCE MANUAL ////////////////////////
PREREQUISITES 
BLEED LOAD CANNOT  MAKE SURE THIS SYSTEM WILL OPERATE: 
BE APPLIED WHEN THE  APU (AMM 49-11-00/201)
APU ENGINE SPEED IS  MAKE SURE THE AIRPLANE IS IN THIS CONFIGURATION: 
100%  ELECTRICAL POWER IS ON (AMM 24-22-00/201) 

POSSIBLE CAUSES:
1.
BLEED AIR VALVE, V56, PROBLEM (AMM 49-52-11/401)

2.  
LEAKAGE FROM THE BLEED AIR DUCT

3.  
LEAKAGE FROM THE AIR LINES ON THE BLEED AIR VALVE

4.
MISCELLANEOUS SWITCHING MODULE, M278, PROBLEM (AMM 52-71-31/401)

5.
ELECTRONIC SPEED SWITCH, S634, PROBLEM (AMM 49-61-22/401)

6.  
LEAKAGE FROM THE AIR LINES BETWEEN THE BLEED AIR VALVE AND THE APU CONTROL THERMOSTAT (AIRPLANES
WITHOUT THE ELECTRONIC TEMPERATURE CONTROL) OR THE PROPORTIONAL CONTROL VALVE (AIRPLANES WITH THE
ELECTRONIC TEMPERATURE CONTROL)

7.  
APU CONTROL THERMOSTAT PROBLEM (AMM 49-52-32/401)(AIRPLANES WITHOUT THE ELECTRONIC TEMPERATURE
CONTROL)

8.  
PROPORTIONAL CONTROL VALVE PROBLEM (AMM 49-52-31/401)(AIRPLANES WITH THE ELECTRONIC TEMPERATURE
CONTROL)

9.
CLOGGED FILTER FOR THE DIFFERENTIAL PRESSURE REGULATOR (AMM 49-52-21/301)

10.
DIFFERENTIAL PRESSURE REGULATOR PROBLEM (AMM 49-52-21/401).

FAULT ISOLATION:
NO

1 START AND OPERATE THE APU  
51 DO THIS PROCEDURE: "APU
(AMM 49-11-00/201).  GEN OFF BUS" LIGHT DOES NOT
WHEN THE APU SPEED WAS COME ON WHEN THE APU ENGINE 95%, DID THE "APU GEN OFF BUS" SPEED GETS TO 95% (FIG. 117). LIGHT COME ON?

YESSEE SHEET 2
(BLOCK 2)

Bleed Load Cannot Be Applied When the APU Engine Speed Is 100 Percent
Figure 119 (Sheet 1)
　
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