CFM56-7 AGB & TRF Oil Leak Troubleshooting Wes Triff December 2002 2 Proprietary Information CFM / GE use only Manpower Materials Machine Method Measurement Environment Heat level in sump area Design of Oil inlet cover flange O-ring material Are pilot squawks justified? Are maintenance squawks justified? Improper troubleshooting Is training focusing on proper troubleshooting? Insufficient technical information available to mechanics Are squawks justified? Lack of understanding of the systems Repetitive Oil Leak Squawks What can cause repetitive squawks?? Oil Type Does AMM present all possibilities? Bad maintenance practices Incorrect Oil Inlet Cover gasket 3 Proprietary Information CFM / GE use only • AGB gearpad seal damage •IDG •MFP •L&S Pump •Oil Inlet Cover O-ring damage •New material being explored •Incorrect Oil Inlet Cover Gasket •Operators with -3 and -7 fleets •340-179-401-0 is -7 only (SB 72-254) •335-107-901-0 is common to -3 & -7 •Early -7 TRF •Aft Sump Scavenge Tube Damage •Aggravated when T/S oil in tailpipe •MTC Malpractice- single-wrench tightening Some Common Sources of HOC/Leaks 4 Proprietary Information CFM / GE use only Common AGB gear pad seal damage origin: •IDG is heavy, frequently “manhandled” into place. Gearpad seal is easily damaged •MFP gear pad is easily damaged if entire fuel package is removed as a unit •L&S Pump gear pad damage not as common, but possible Standard Troubleshooting: •Identify and bag gearbox pad drains •Idle leak check, or 70% N1 power run: NOT always sufficient to pressurize gearbox sufficiently to detect leak Result: •Repeat write-ups, pilot refusals, needless component changes, and Delays & Cancellations! AGB Leaks 5 Proprietary Information CFM / GE use only Suggested Troubleshooting: •If run to 70% does not clearly identify source of leak - Internal pressure only reaches 19PSI •Run to T/O power for 2 minutes if allowed at station - Allows AGB to reach 25PSI •rocedure proven multiple times •AMM PCR submitted: Allow engine run to T/O power to clearly isolate source of oil leak; previously limited to 70% N1 CFM56-7 Operational AGB Oil Pressure 6 Proprietary Information CFM / GE use only CFM56-7 Operational AGB Oil Pressure Current AMM Recommendation T/O Power Suggested for “problem” leakers 7 Proprietary Information CFM / GE use only Oil Inlet Cover O-ring Embrittlement •Frequent cause of excess oil in the tailpipe •New material under investigation 8 Proprietary Information CFM / GE use only Results of Over-tightening TRF Scav. Tube This failure caused a tailpipe fire 9 Proprietary Information CFM / GE use only In correct gasket can cause air/oil leaks 10 Proprietary Information CFM / GE use only In correct gasket can cause air/oil leaks Who’s at Risk? •Operators with -3 and -7 fleets •340-179-401-0 is -7 only (SB 72-254) •335-107-901-0 is common to -3 & -7 •Early -7 TRF What is the result? •Heavy coked-on oil deposits on oil inlet cover and aft cover walls 11 Proprietary Information CFM / GE use only Summary AGB gear pad seal Leakage: •Run to higher power to get a definite origin Oil Inlet Cover O-ring leakage •Very common source of leakage/excess coking •Tightening of TRF Oil tube not needed to replace O-ring •O-ring can be replaced on-wing •Ensure proper gasket usage •340-179-401-0: -7 only •335-107-901-0: -7 and -3 common TRF Oil Tube Cracking: •AFT sump drain tube not documented as a leak source •Stress 2-wrench method if MTC must mess with it •Consequence is excessive oil loss and possible fire作者: kinran 时间: 2011-6-4 23:08:52
rocedure proven multiple times