波音737飞机737-SL-71-062

BOEINGCommercialAviationSERVICE LETTERServicesFLEET SUPPORT ENGINEERING.BOEING COMMERCIAL AIRPLANES.P.O.BOX3707.SEATILE.WASHINGTON98124-2207737-SL-71-062ATA:7100C8012 October 2009SUBJECT:ENGINE-MOUNTED FAN COWL RADIAL SUPPORT BRACKETIMPROVEMENTMODEL:737-600 to -900ER and BBJAPPLICABILITY:All 737-600 to -900ER and BBJ Airplanes from Line Position 184through Line Position 2599 and all new or overhauled CFM56-7Bengines with new or partial Boeing QEC kits delivered from August2001 through March 2009.REFERENCES:a)737-600 through-900ER and BBJ Aircraft Illustrated Parts Catalog(AIPC)71-40-51-01 B Item210,225and71-00-51-14Item225,240b)737-600 through-900ER and BBJ Power Plant Buildup Manual(PPBUM)71-00-02 Figure 6-1 Item 350SUMMARY:This service letter advises of the availability of an improved reference a)engine-mounted fancowl radial support bracket,which was introduced to resolve in-service cracking events with aprior bracket design.BACKGROUND:Commencing with entry into service of the 737NG-series airplanes in 1997 and as supplied inearly Quick Engine Change (QEC)kits,Boeing delivered the reference a)P/N 332A2930-11radial support bracket assembly.The purpose of this bracket is to guide the right-hand fan cowlinto position prior to latching with the left-hand fan cowl.During a subsequent producibilityreview,the existing design was changed to a P/N 332A2930-83 bracket assembly,which wasfirst delivered on 737NG airplanes from Line Position 184 and delivered in QEC kits fromAugust 2001.Line Position 184 was delivered in February 1999.Shortly after entry into service of the P/N 332A2930-83 bracket assembly,Boeing beganreceiving reports of cracking of one or both of the guide tangs,which in several instancesresulted in separation of these tangs.An investigation concluded the cracking was due toinsufficient strength in the guide tangs of the P/N 332A2930-83 bracket design,which wasmachined from multiple flat aluminum sheets in lieu of the single titanium casting used on the