EGT Harness Contamination CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 2 • D&C’s due to EGT indication 50-100°C lower than adjacent engine - Drift down occurs gradually over a 2-3 week period - Confirmed by trend monitoring Fleet Experience EGT drift FF / VSV / N2 stable 3 weeks CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 3 • Anomaly corrected by replacement of lower, higher or junction box harness - Faulty harness detected per on-wing AMM inspection/check 77- 21-10-601 • Low time occurrence failure mode: - Drift down reported on first run engines below 3000 hours All Engines Over 3000 Hours Not Affected by EGT Indication Drift Fleet Experience CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 4 Investigation • Electrical test...insulation resistance discrepancies - Low insulation resistance or short circuit between Cr/Al wires - Consistent with EGT signal drift down • Harness strip down...black deposit contamination inside glass sealing at con o ’clad tip area - Extensive quality audit conduced at Auxitrol - Root cause of contamination identified - Poor piece part cleaning after machining operation at subcontractor level CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 5 Contaminant Location Contaminant location CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 6 Corrective Actions • Production level - Ultrasonic cleaning with appropriate solvent implemented from Jan. 2002 - Engine ESN introduction - CFM56-5B/P SAC, 575383 - CFM56-5B/2P DAC, 575910 CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 7 • Suspect harness population defined - Harnesses produced from Sept. 98 to Dec. 01 • SB 77-0006 (-5B), cat 4, released Aug 2001: - For affected -5B engines below 3000FH - Detection of gradual EGT drift down through the current EGT trend monitoring - Crew observation of EGT mismatch - AMM 77-21-10-601 inspection and replacement of faulty harness - Revision 1 targeted end May 2002 Field Recommendations CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 8 Field Recommendations • S/B 77-0008 (-5B), cat 1, to track/replace EGT harnesses delivered by Vendor as LRU spare parts - For harnesses having cumulated less than 3000FH - Replacement of identified LRU spare parts according to Vendor list - To be mandated by Agencies - Issued March 2002 • Field contaminated harnesses replaced/reworked at no cost by the Vendor作者: kinran 时间: 2011-6-4 23:06:53
