737 AMM 飞机维护手册 防火 FIRE PROTECTION(29)

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B.  False alarms are usually intermittent and rarely remain for any length of time. High ambient temperature and APU heat may cause a false alarm. The system will usually become operable again after a short time. If a false alarm should remain after the accessory unit is replaced, isolation of the faulty detector, connector or interconnecting wiring will be required. Isolation of the faulty component can be accomplished with the help of the trouble shooting chart.
C.  The detector and interconnecting wiring can be checked with an ohmmeter. An open detector can be found by making a continuity check between center pins or sockets on connectors on the ends of the detector. Shorts can be found by checking for continuity between the pins or sockets and the shell of the connector. If moisture in a connector is found to be the cause of a false alarm, remove moisture by blowing out connectors with dry nitrogen.
D.  prior to making any tests, equivalent connectors should be installed at the plug or receptacle of the detector or airplane wiring. The test connector should have exposed contact points to attach or touch test probes. If test connectors are not used, an oversized test probe may be forced into a socket of the sensor connector; this may spread the contacts and prevent the pin of the mating connector from making proper contact.
E.  Whenever the fire control module (P8-1) is replaced, test the APU fire detection system (Ref 26-15-02).
2.  Prepare for Trouble Shooting
A.  Provide electrical power (Ref 24-22-0, MP).
B.  Check that AURAL WARN, MASTER WARN & CONTROL, and APU FIRE PROTECTION DETECTION circuit breakers on panel P6-2 are closed.
C.  Open FIRE PROTECTION DETECTION ENG NO 1, ENG NO 2, and OVHT WHL WELL WNG BDY circuit breakers on panel P6-2.
Feb 20/85 26-15-02 Page 101
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

3. APU Fire Detection Trouble Shooting Chart APU FIRE DETECTION SENSING ELEMENT - REMOVAL/INSTALLATION

5C9 
26-15-02 Page 102  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Oct 20/83 

1.  Prepare for Removal of Sensing Element
A.  Open APU CONT and APU fire detection circuit breakers on load control center P6.
B.  Open APU compartment access door latches and open access door. Install door support rods.
C.  Support APU lower shroud, open shroud latches and clamps. Remove shroud.
2.  Remove APU Engine Sensing Element (Fig. 401, 402)
A.  Remove lockwire from connectors and disconnect cable from element fittings. Discard copper gasket on configuration I electrical connector. On configuration II electrical connector, copper gasket is an integral part of connector and need not be removed. Install protective caps on electrical connectors.
B.  Remove jamnuts from element fittings.
C.  Release clamps along length of element.
NOTE:  Support element when releasing clamps. Keep bending of element to a minimum.
NOTE:  Overheat sensing element M276 may have a short silicone tube installed over the element in critical locations to aid in prevention of false overheat annunciation. When removing this element, discard the lacing tape and retain the silicone tube for re-installation, if it is serviceable.
D.  Slide element clear of bracket and remove.
E.  Replace jamnuts on element fittings and install protective caps.
3.  Remove APU Exhaust Sensing Elements (Fig. 401, 402)
A.  Remove lockwire from connectors and disconnect cable from exhaust fire sensing element. Install protective caps on sensing element and connector.
B.  Disconnect cable leading to exhaust overheat sensing element. Install protective caps on connector. Tape sensing element cable and connector to heat shield and muffler assembly.
5E2 
May 01/99  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  26-15-12 Page 401 

H21676 H21679 H21683
APU Fire Detection Sensor Installation  506 
26-15-12 Page 402  Figure 401 (Sheet 1) BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Feb 1/75 

506  APU Fire Detection Sensor Installation 
Feb 20/88  Figure 401 (Sheet 2) BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  26-15-12 Page 403 

APU Fire Detection Sensor Installation  511 
26-15-12 Page 404  Figure 401 (Sheet 3) BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  May 1/75 

C.  Gain access through door 3802 and remove four bolts attaching drip pan. Remove drip pan.
D.  Remove screws attaching aft fairing to tail cone.
　
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