ARE THE RESISTANCES 0-1 OHMS (MAXIMUM)? YES
NO
22 MEASURE THE RESISTANCE AT THE ELECTRONIC SPEED SWITCH, S634, CONNECTOR D1245, FROM PIN G TO PIN H (WDM 49-31-01).
IS THE RESISTANCE 4000-6000 OHMS? YES
NO
23 MEASURE THE RESISTANCE AT THE ELECTRONIC SPEED SWITCH, S634, CONNECTOR D1245, FROM PINS A TO G, M TO F, L TO E B TO G (WDM 49-31-01).
ARE THE RESISTANCES A MINIMUM OF 1000K OHMS?
YES NO
24 MEASURE THE RESISTANCE AT THE SEQUENCING PRESSURE SWITCH FOR THE OIL, CONNECTOR D1250, FROM PIN 3 TO PIN 4 (WDM 49-31-01).
IS THE RESISTANCE MORE THAN 1000K OHMS?
YES SEE SHEET 3 (BLOCK 25)
APU Engine Speed Decreases
Figure 125 (Sheet 2)
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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////////////////////////A / GTCP85-129 SERIES /737-300/400/500/ ENGINES /MAINTENANCE MANUAL ////////////////////////
FROM SHEET 2 (BLOCK 24)
YES
NO
25 MEASURE THE RESISTANCE AT
THE FUEL SOLENOID VALVE, CON-
NECTOR D1264, FROM PIN A TO
PIN B (WDM 49-31-01).
ARE THE RESISTANCES 20-45 OHMS?
YES
NO
26 DO A CHECK FOR THE INTER-
MITTENT ELECTRICAL SIGNAL AT
THE ELECTRONIC SPEED SWITCH
(110% SWITCH), S634, CONNECTOR
D1245, PIN E (WDM 49-31-01).
IS THE ELECTRICAL SIGNAL TO PIN E CONTINUOUS AND STRONG?
YES
NO
27 DO A CHECK FOR THE INTER-
MITTENT ELECTRICAL SIGNAL AT
THE SEQUENCING PRESSURE SWITCH
FOR THE OIL, CONNECTOR D1250,
PIN 3 (WDM 49-31-01).
IS THE ELECTRICAL SIGNAL TO PIN 3 CONTINUOUS AND STRONG?
YES
NO
28 DO A CHECK FOR THE INTER-MITTENT ELECTRICAL SIGNAL AT
THE FUEL SOLENOID VALVE, CON-
NECTOR D1264, PIN A
(WDM 49-31-01).
IS THE ELECTRICAL SIGNAL TO PIN A CONTINUOUS AND STRONG?
62 REPLACE THE CAUSE OF THE INTERMITTENT ELECTRICAL SIGNAL.
APU Engine Speed Decreases
Figure 125 (Sheet 3)
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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PREREQUISITES
MAKE SURE THE AIRPLANE IS IN THIS CONFIGURATION: ELECTRICAL POWER IS ON (AMM 24-22-00/201)
APU ENGINE SPEED DECREASES
POSSIBLE CAUSES:
1.
INLET DOOR SWITCH, S284, PROBLEM OR ADJUSTMENT (AMM 49-15-00/501)
2.
INTERMITTENT ELECTRICAL SIGNAL TO THESE COMPONENTS: . FUEL SOLENOID VALVE (AMM 49-31-31/401) . SEQUENCING SWITCH FOR THE OIL PRESSURE (AMM 49-61-41/401) . ELECTRONIC SPEED SWITCH, S634, (AMM 49-61-22/401).
3.
APU CONTROL UNIT, M280, PROBLEM (AMM 49-61-11/401).
FAULT ISOLATION:
NO
1 DO A CHECK OF THE
ADJUSTMENT OF THE INLET DOOR
SWITCH, S284
(AMM 49-15-00/501).
IS THE INLET DOOR SWITCH ADJUSTED CORRECTLY?
YES
YES
2 REMOVE THE INLET DOOR
SWITCH, S284, CONNECTOR D1246.
IS THERE DAMAGE TO THE
CONNECTOR?
NO
NO
YES
NO
4 EXAMINE THE CIRCUIT FROM
THE INLET DOOR SWITCH, S284,
CONNECTOR D1246, PIN 4, TO THE
APU CONTROL UNIT, M280,
CONNECTOR D50B, PIN 46
(WDM 49-31-01).
IS THE CIRCUIT OK?
YES SEE SHEET 2
(BLOCK 21)
52 REPAIR THE DAMAGE THAT YOUFIND.
IF NECESSARY, REPLACE THE INLET DOOR SWITCH, S284.
APU Engine Speed Decreases
Figure 125A (Sheet 1)
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details. 中國航空網 m.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：737-300 400 500 AMM 飛機維護手冊 AIRBORNE AUXILIARY POWER 1(47)
