737 AMM 飞机维护手册 点火 IGNITION(6)

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A.  Engine ignition system examination encompasses the ignition system ignition exciter, high tension leads and igniter plugs.
2.  Examine Ignition System (General)
WARNING:  IGNITION SYSTEM VOLTAGE IS DANGEROUSLY HIGH. IGNITION SWITCH MUST BE IN "OFF" POSITION BEFORE REMOVAL OF ANY IGNITION COMPONENTS. ALLOW SEVERAL MINUTES TO ELAPSE BETWEEN OPERATION OF IGNITION SYSTEM AND REMOVAL OF IGNITION COMPONENTS. IMMEDIATELY UPON DETACHING IGNITER CABLE FROM IGNITER PLUG, DISCHARGE CURRENT BY GROUNDING IGNITER CABLE TERMINAL TO ENSURE COMPLETE DISSIPATION OF ENERGY FROM IGNITION SYSTEM. FAILURE TO FOLLOW THIS PROCEDURE COULD RESULT IN SEVERE INJURY TO PERSONNEL.
A.  Examine the completely assembled ignition system to assure that all wiring and connections are tight and in good condition.
B.  Assure that all openings are covered with external covers, not internal plugs, immediately upon removal or disassembly of parts.
C.  Examine all ignition wiring for chafing, breaks, wear and security.
D.  Check the entire engine compartment for cleanliness after completion of any work.
3.  Examine Ignition Exciter
A.  Examine input connector for bent or damaged pins. Bent pins may be straightened using needlenose pliers. Damaged pins will require overhaul.
B.  Examine output receptacle well for damage or signs of arcing or flashover on contact button. Arcing is identified by pitting or discoloration on contact. Flashover is identified by carbon tracking. If any of these indications are evident, send exciter to overhaul facility.
C.  Examine the threads of each outlet. Minor repair to threads can be made by chasing with proper die. If threads are damaged beyond minor repair, ignition exciter will require overhaul.
D. Examine case for cracks, dents or large abrasions.
Examine High Tension Leads

A.  Examine conduit for cuts, abrasion or other damage, and coupling nuts for worn or stripped threads.
B.  Examine high tension contact and cable.
CAUTION:  DO NOT BEND OR PULL HIGH TENSION CABLE CONDUCTOR WIRE, OR INSULATION WILL BE DAMAGED.
501 
Feb 20/88  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  74-00 Page 601 

 

(1)  
During rubber bushing replacement, inspect for evidence of arcing or flashover on high tension electrical contact. Inspect exciter-to-igniter plug cables to ensure that excessive temperature has not affected insulation and grommets (Fig. 601). Arcing is identified by pitting and discoloration (Fig. 602). Flashover is identified by carbon tracking (Fig. 603). If either indication is evident, send assembly to repair facility.

(2)  
If conductor insulation is hard, brittle, or cracked, send assembly to repair facility.

(3)  
Examine for presence of oil, dirt, or conductive contaminants on exposed parts. Use cleaning procedures as required (Ref Cleaning/Painting).

5.  Examine Igniter Plugs (Fig. 604, 605)
A.  Visually examine connector threads and shell threads of igniter. If damaged, chase threads using 1.000-2ONS-3A for connector threads and 0.9375-16NS die for shell threads.
B.  Examine ceramic for cracks on either end of plug. Any cracks in ceramic are cause for rejection on igniter plug. Internal ceramic breaks or cracks are detected by shaking plug and listening for rattle.
C.  Examine wear of plug by using lighted magnifying glass looking through shell end annulus to determine if insulator supporting shoulder is worn through. Wear of Champion plug may be measured using service wear measuring tool CT-468 or CT-492.
NOTE:  Visual determination of excessive wear is presently only practical means of evaluating plug wear. Maximum outer shell ID erosion is a physical limit to prevent possible loss of ceramic support by the ground shell which can result in ceramic cracking and internal firing. When excessively eroded, the ceramic can be ingested by the turbine. Center electrode depth may be used to determine plug serviceability limit when preferred by individual operators.
Service wear measuring tool CT-468 or CT-492 may be purchased from: Champion Spark Plug Co, 900, Upton, Toledo, Ohio 43601 U.S.A.
Although igniter plugs will continue to fire after exceeding erosion limits, the voltage required to discharge across the spark gap increases with increasing erosion and can stress other components, particularly the high tension parts.
D.  Examine igniter plugs in areas shown per Fig. 604 and 605 for abrasion. Reject plugs not meeting required abrasion wear limits caused by combustion chamber igniter plug guide.
E.  Whenever high tension lead is removed from igniter plug terminal, examine igniter plug terminal well.
(1)  Examine igniter plug terminal for evidence of arcing and flashover. Arcing is identified by pitting or discoloration on contact (Fig. 602). Flashover is identified by carbon tracking (Fig. 603). If any of these indications are evident, replace igniter plug.
　
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