ENGINE FIRE DETECTION SYSTEM - TROUBLE SHOOTING
EFFECTIVITY
GJ B2501 thru B2505
GJ B2511 thru B2515
1. General
A. Fire detection system trouble will usually be indicated by absence of fire warning lights and alarm bell or overheat lights when the test switch is operated on the fire protection module, or by a false alarm. If a short circuit has occurred on a sensing line, the associated detector inoperative light on the engine and APU fire detection accessory unit will probably be illuminated. If an open circuit has occurred, the associated warning lights and detector inoperative lights will not be illuminated when the system is tested. Lights on the fire protection module, master caution annunciator and fire warning lights should be tested before assuming the detection system is faulty by operating the master lights test circuits (Ref 33-15-0 AT). The detector inoperative lights on the accessory unit may be pressed to test operation.
B. False alarms (engine overheat or fire warnings) are usually intermittent and rarely persist for any length of time. Intermittent false warnings can occur whenever the system is subjected to vibration; i.e. engines running, in flight, taxiing, etc. False warnings can occur with the ENG OVHT DET switch in either NORMAL or FIRE position. If a false alarm should persist, isolation of the individual sensor, connector or interconnecting wiring will be required. Isolation of the faulty component can be accomplished with the help of the trouble shooting charts.
C. The sensors and interconnecting wiring can be checked with an ohmmeter. An open sensor can be found by making a continuity check between center pins or sockets on connectors on the ends of the elements. Shorts can be found by testing for continuity between the pins or sockets and the shell of the connector. If moisture in a connector is found to be cause of false alarm, remove moisture by blowing connectors with dry nitrogen.
D. Prior to testing, equivalent connectors should be installed at the plug or receptacle of the sensor 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. Test fire protection module P8-1 after installation (Ref 26-11-0 AT).
5C8
May 01/98 26-11-0 Page 101
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
2. Prepare to Trouble Shoot
A. Check that the following circuit breakers on panel P6 are closed:
(1)
AURAL WARNING
(2)
MASTER WARN & CONTROL
(3)
All IND LIGHTS
(4)
ENG 1 FIRE DET
(5)
ENG 2 FIRE DET
B. Open the following circuit breakers on panel P6:
(1)
WHEEL WELL WING AND LWR BODY OVHT
(2)
APU FIRE DET
C. Apply power.
5C8
26-11-0 Page 102 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Jun 20/85
3.
Overheat Detection Trouble Shooting Chart
4.
Fire Detection Trouble Shooting Chart
500
Feb 20/92 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 26-11-0 Page 103
500
26-11-0 Feb 20/92
Page 104
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
5C8 Overheat Detection Minimum Insulation Resistance
Feb 20/87 Figure 101 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 26-11-0 Page 105
Fire Detection Minimum Insulation Resistance 5C8
26-11-0Page 106 Figure 102 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Feb 20/87
ENGINE FIRE DETECTION SYSTEM -ADJUSTMENT/TEST
EFFECTIVITY
GJ B-2501 thru B-2505
GJ B-2511 thru B-2515
1. General
A. The engine fire detection system monitors the engine nacelle temperature for fire and overheat or fire conditions.
B. The system uses power from the 28-volt dc battery bus. The circuit breakers are on the P6 panel.
C. The engine fire detection system components are: the fire detectors, the engine and APU fire detection accessory unit, and the engine and APU fire control panel.
D. There are two tasks in this section:
(1)
Do the Operational Test of the Engine Fire Detection System
(a) The operational test is done in a minimum of time, and uses equipment installed on the airplane to make sure that the system will operate correctly. 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 防火 FIRE PROTECTION(11)
