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时间:2011-03-30 10:25来源:蓝天飞行翻译 作者:航空
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1.  General
A.  Fire detection system trouble will usually be indicated by false alarm or absence of fire warning lights and alarm bell or overheat lights when the test switch is operated. If a short circuit has occurred, 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 control 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 are usually intermittent and rarely remain for any length of time. High ambient temperature and engine 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 charts.
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 elements. Shorts can be found by testing for continuity between the pins or sockets and the shel1 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 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 detector 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).
2.  Prepare to Trouble Shoot
A.  Check that the following circuit breakers on panel P6-2 are closed: 
(1)  
AURAL WARN

(2)  
MASTER WARN & CONTROL 

(3)  
All INDICATOR (nine circuit breakers)

(4)  
FIRE PROTECTION DETECTION ENG 1

(5)  
FIRE PROTECTION DETECTION ENG 2 


B.  Open the following circuit breakers on panel P6-2: 
(1)  
WHEEL WELL WING AND LWR BODY OVHT

(2)  
FIRE PROTECTION DETECTION APU


C.  Apply power (Ref 24-22-0 MP).
Aug 01/94 26-11-02 Page 101
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

5C9 
26-11-02 Page 102  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Jun 20/90 


ENGINE FIRE DETECTION SENSING ELEMENT - REMOVAL/INSTALLATION
1. General
A.  One sensing element is installed on the lower right side of each engine, a second element is installed on each engine strut firewall. Access to the engine sensor is gained by opening the right cowling panel. Access to the firewall sensor is gained by removing the outboard upper fixed fairing (Ref Chapter 71, Fixed Fairing).
2.  Equipment and Materials
A.  Bonding Meter (Ref 20-22-01)
B.  Grease - Silicone, Dow Corning DC-4
3.  Sensing Element - Removal/Installation
NOTE:  The removal and installation of the sensing elements should be completed one element at a time. The operational test must be performed after each individual sensing element is removed and installed.
A.  Remove Sensing Element (Fig. 401, 402)
(1)  
Open applicable FIRE PROT DET ENG circuit breaker on load control center P6.

(2)  
Remove lockwiring and electrical connectors from element fittings at each end of element. On configuration I electrical connector, discard copper gasket. On configuration II electrical connector, copper gasket is an integral part and need not be removed. Install protective caps on electrical connectors.

(3)  
Remove jamnuts and bonding jumpers from aft element fittings per 20-10-185.

(4)  
Remove forward element fitting from structure by loosening mounting screw.

(5)  
Release clamps along length of element.

NOTE:  Support element when releasing clamps. Keep bending of element to a minimum.

(6)  
Remove aft element fittings from bracket and pull element free of engine.

(7)  
Replace jamnuts on element fittings and install protective caps.
 
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