CFM56-7 AGB & TRF Oil Leak Troubleshooting

航空

游客，如果您要查看本帖隐藏内容请回复

航空

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

kinran

bocome

CFM56-7 AGB & TRF Oil Leak Troubleshooting