EGT Harness Contamination

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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

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EGT Harness Contamination

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EGT Harness Contamination