(2)
Do the APU normal shutdown (AMM 49-11-0/201).
(3)
Attach a DO-NOT-OPERATE tag to the APU master switch on the P5 forward overhead panel.
(4)
Visually examine the high-pressure fuel filter for any signs of leakage:
(a) If you found signs of leakage, repair the cause of it.
Aug 01/95 49-31-81 Page 301 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
A72343
High Pressure Fuel Filter -Servicing 597
49-31-81 Figure 301 Oct 20/92
Page 302
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
FUEL HEATER CHECK VALVE - REMOVAL/INSTALLATION
1. General
A. The fuel heater check valve is used to isolate possible APU fuel feed system air leakage and to maintain a supply of fuel for priming the APU fuel pump for starting. To remove and install the fuel heater check valve, refer to the removal/installation of the fuel heater, 49-31-61.
543
Feb 15/73 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 49-31-91 Page 401
FUEL SENSING FLOW CONTROL VALVE - REMOVAL/INSTALLATION
1. General
A. The fuel sensing flow control valve is part of the fuel heater system. When the temperature of the fuel passing through the valve drops to a predetermined value, the valve will modulate open.
2. Prepare to Remove Fuel Heater
A. Position BATTERY SWITCH and APU START SWITCH to OFF and placard that APU maintenance is "in work."
B. Open circuit breaker on M280 module-APU accessory unit on E3-3 electronic shelf.
C. Open APU compartment access door latches and open door. Install door support rods.
D. Support lower shroud, open shroud latches, and remove shroud.
CAUTION: EXERCISE CARE NOT TO DAMAGE SHROUD DRAIN LINES WHEN HANDLING SHROUD.
E. Disconnect and remove fire detection element from APU.
F. Remove overtemperature control switch (Ref. 49-52-81, Removal/Installation).
G. Remove pneumatic solenoid valve (Ref 49-61-31, Removal/Installation).
H. Remove clamps securing cooling air crossover duct at oil cooler and cooling air fan housing.
I. Remove screw and washer securing cooling air crossover duct to generator.
J. Remove and rotate duct to gain access to fuel sensing flow control valve.
3. Remove Fuel Sensing Flow Control Valve (Fig. 401)
A. Disconnect all plumbing from valve.
B. Remove screws and washers securing clamp to bracket.
C. Remove clamp and fuel sensing flow control valve.
4. Install Fuel Sensing Flow Control Valve (Fig. 401)
A. Loosely assemble all plumbing to fuel sensing flow control valve.
B. Install clamp using screws and washer.
C. Secure fuel sensing flow control valve and fittings.
5. Restore Airplane to Normal Configuration
A. Position cooling air crossover duct so that ports are aligned with cooling fan housing, generator and oil cooler. Install screw and washer securing duct to generator.
B. Install and tighten clamps securing duct to cooling air fan housing and oil cooler.
C. Install pneumatic solenoid valve (Ref. 49-61-31, Removal/Installation).
D. Install overtemperature control switch (Ref. 49-52-81, Removal/ Installation).
E. Install fire detection element on APU (Ref 26-15-11, Removal/Installation).
F. Test fuel sensing flow control valve, refer to adjustment/test.
May 15/78 49-31-92 Page 401 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
G20474
Fuel Sensing Flow Control Valve Installation 500
49-31-92 Figure 401 Nov 15/79
Page 402
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
FUEL SENSING FLOW CONTROL VALVE -ADJUSTMENT/TEST
1. General
A. This test procedure applies to the fuel heater system. With APU operating and lower shroud removed, check airflow from heater bleed air over board dump line to check the valve for operation.
2. Test Fuel Sensing Flow Control Valve (Fig. 501)
A. Operate APU (Ref 49-11-0/201)
B. Record fuel temperature indicator on forward overhead panel.
C. APU's WITH ALLIEDSIGNAL SB GTCP85-49-7096;
Note TABLE 1. Fuel temperature versus overboard airflow.
Fuel Temperature Indicator Airflow at the Overboard Dump Line for the Bleed Air
Above 620F (170C) 620F (170C) or Lower Small Quantity or No Airflow Airflow
Fuel Sensing Flow Control Valve Test 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：737 AMM 飞机维护手册 机载辅助动力AIRBORNE AUXILIARY POWER(68)
