CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 1 Accessory GearBox Links Bearing Wear Components & Accessories CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 2 Background • Several reported AGB links bearings severely worn on CFM56-7B engines CFM56-3 also affected to a lesser extend • 3 parts involved: upper non-adjustable link: bearings damaged on both ends of the link no measurable longitudinal displacement “worst case” highly worn bearing axial 3-5 mm [0.118” to 0.197”] not received yet lower non-adjustable link: no wear reported adjustable link: similar axial wear reported on 30% of inspected engines Components & Accessories AGB Link Wear Axial CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 3 VVeerryylilmimititeeddlolonnggitituuddininaallddisispplalacceemmeenntt//HHigighhaaxxiaiallddisispplalacceemmeenntt Self Lubricating Feature Wear longitudinal axial link Spherical Bearing External Link inner surface Components & Accessories AGB Link Wear CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 4 Engineering assessment • Phenomenon/ root cause: wear induced by engine vibration Link retaining feature loaded by link weight Self lubricating feature degradation • Consistency of root cause: Angular work combined with link weight leading to Bearing degradation horizontal upper non-adjustable link most damaged • Effect of wear: effect on AGB position acceptable heavy bearing axial wear may lead to contact between Link, and AGB Hinge Fitting wear (not experienced yet) – Axial wear to be limited to 1.3 mm [0.051”] longitudinal wear would impact AGB mounting system vibrations damping capability – Longitudinal wear to be limited to 0.2 mm [0.008”] Components & Accessories AGB Link Wear CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 5 Corrective Action Plan • Further investigations on “worst case” When parts received Oct, 02 • AMM limits proposal Any amount until the Link FWD edge is in contact with the ABG Hinge Fitting – Maximal authorized wear covered by the Link / Fitting gap – Measurement in this environment seems not easy If the link in contact with the Hinge an overserviceability of 500 cycles is allowed • Short term containment Field Plan Temporary repair by implementation of RTV – 3 RTV types are proposed depending of the available curing time – RTV injection between link and AGB Hinge Fitting to set the link in the proper position and support it’s weight under vibration – Implementation through CDR (Already applied in field) Components & Accessories CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 6 Corrective Action Plan (cont’d) • Mid term Field Plan : Fit check exercize at the training school was performed to validate the Upper Link replacement on-wing – Different Upper Link dimensions have been tested Drawing Link longitudinal tolerance is +/- 0.3 mm [+/- 0.012”] Mechanic was able to install a link within 0,2 mm [0.008”] of the removed one. Impossible to install a link at the Max. tolerance value – The replacement of the link on-wing will not be implemented in the AMM Link Repair – Bearing replacement procedure in process – will be a generic repair for all bearings December, 02 Components & Accessories AGB Link Wear CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 7 Corrective Action Plan (cont’d) Final fix Plan Different solution under study – Removable Spherical Bearings Review with the proposed vendor completed One bearing definition has been identified Installation study to be performed – Introduction of a Teflon washer – Introduction of a bigger Spherical Bearing Final Fix selection December,02 Components & Accessories AGB Link Wear作者: kinran 时间: 2011-6-4 22:58:17
