标题: CFM56-7B VBV Teflon Pad Disbond [打印本页] 作者: 航空 时间: 2011-4-14 10:47:39 标题: CFM56-7B VBV Teflon Pad Disbond
作者: 航空 时间: 2011-4-14 10:49:12
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 1 CFM56-7B VBV Teflon Pad Disbond CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, February 2002 WTT face to face or Export are Prohibited Background • About 20 cases of teflon pad disbonding reported to date Either seen on wing or at shop level – 1 to 4 pads disbonded or missing 50% cases leading to VBV position signal disagree fault occurrence – 150 hours time limited dispatch (short time dispatch fault) CFM56-7B VBV Teflon Pad Disbond Pad debonded CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, February 2002 WTT face to face or Export are Prohibited Root Cause Investigation • Lack of teflon pad bonding evidence on all parts returned from field • No manufacturing concession recorded • All defective parts coming from same sub-contractor source • About 1,700 pads potentially affected manufactured since EIS 440 engines potentially affected (87X 101 - 87X 541) Corrective Action • Original source canceled • New vendor process quality confirmed through shear test – New part = 34 Mpa – After wet aging (1500 hrs) = 22 Mpa – CFM spec. requirement = 18 Mpa Root Cause understood = Poor bonding quality from original vendor CFM56-7B VBV Teflon Pad Disbond February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 4 Over-serviceability • Four pads mounted in pair, one @ 2 O’clock, one @ 8 O’clock • If at least one pad remain at each pair location -> serviceable, no time limit • If one pair missing or more -> serviceable up to shop visit To be introduced in the next AMM revision (Feb 2002) EEC Software logic • VBV position signal disagree fault maintenance message de-sensitized VBV fault threshold increased from fixed 4° to variable limit (function of VBV command) – Validated through engine test introduced in coming 7BN EEC software to be released in Apr 2002 CFM56-7B VBV Teflon Pad Disbond February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 5 LH pair of two pads RH pair of two pads Aft looking Fwd CFM56-7B VBV Teflon Pad Disbond CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, February 2002 WTT face to face or Export are Prohibited In-service Plan • No on-wing inspection needed Except for VBV fault troubleshooting per FIM • Inspection in shop of affected population recommended No action required if no pad disbonded 4 pads replaced / repaired if at least one found disbonded – Teflon pad removal requires fan minor module removal VBV Pad Repair • Repair bonding process has been developed and validated This repair does not require an industrial validation • First repair source (Le Piston Français) to be validated by Mar 2002 CFM56-7B VBV Teflon Pad Disbond作者: kinran 时间: 2011-6-4 23:23:36
