CFM56 Number 4 Bearing Status

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CFM56
Number 4
Bearing Status
Overview
• Fleet experience
• P/N 901 Action Plan
• New outer race material
• Shop improvements
• Monitoring system
• Summary
CFM56 Operators Conference – May 21 - 22, 2001 CFM Proprietary Data Unauthorized Disclosure Prohibited 3
CFM56-All - UER & IFSD rates , #4 bearing fail cause
IFSD
Feb00 : 1,80
Jan02 : 0.97
0,00
1,00
2,00
3,00
4,00
5,00
Fail per million EFH - 12 month rolling
0
100 000 000
200 000 000
Cumul effective flight
hours
UER + IFSD
"UER"
Fleet Experience
# 4 Bearing Reliability on CFM56 Fleet Has Been Improving Since 1999
However, Some Variability Between Engine Models
CFM56 Operators Conference – May 21 - 22, 2001 CFM Proprietary Data Unauthorized Disclosure Prohibited 4
Fleet Experience
1999 2000 2001
IFSD UER IFSD UER IFSD UER
-5C 10 (3.71) 3 (1.11) 6 (1.84) 2 (0.61) 5 (1.52) 1 (0.30)
-7B 2 (1.07) 1 (0.54) 2 (0.57) 3 (0.85) 1 (0.19) 2 (0.39)
-3 4 (0.37) 5 (0.46) 5 (0.46) 5 (0.46) 3 (0.28) 7 (0.66)
-5A 4 (1.62) 2 (0.81) 2 (0.78) 1 (0.39) 2 (0.74) 2 (0.74)
-5B 0 (0.00 ) 0 (0.00) 0 (0.00) 1 (0.54) 2 (0.80) 0 (0.00)
(…) Rolling average in event number per MEFH
Failure Rate Is Higher on CFM56-5C Model
Events distribution by engine model and by year
CFM56 Operators Conference – May 21 - 22, 2001 CFM Proprietary Data Unauthorized Disclosure Prohibited 5
0
10
20
30
40
50
60
2000 6000 10000 14000 18000 22000
TSN - TSI
Number of failures
TSN (1st run)
TSI (2nd run & above)
Fleet Experience - Failure Distribution
Bearing Failure Has an Infant Mortality Characteristic
Over 80% of Failures Below 6000 Hrs Since LPT Module Installation
CFM56 #4 Bearing Failures Ages Distribution
(February 2002)
CFM56 Operators Conference – May 21 - 22, 2001 CFM Proprietary Data Unauthorized Disclosure Prohibited 6
P/N 901 Action Plan
• P/N 340-167-901-0 (SNR Source) is experiencing a higher
failure rate than than the other P/Ns
- About 850 parts reported to be installed through CFM tracking database
- 15 reported failures: 1 on -3, 2 on -5A, 5 on -7B and 7 on -5C
- P/N 901 averaged MTBF on CFM fleet is about 277 K hours
- To be compared to 1,300 K hours for other P/Ns
• Specialist working group has been formed to investigate these
events and failure identify root cause & action plan
CFM56 Operators Conference – May 21 - 22, 2001 CFM Proprietary Data Unauthorized Disclosure Prohibited 7
P/N 901 Action Plan
• Quality inquiries on bearings have not evidenced
abnormalities in manufacturing process of this P/N
• As of today, no major contributors on engine
environment found through failed engine
investigations
• Precautionary actions
- P/N 901 installation on CFM production engine was stopped
in 3Q01
- P/N 901 delivery as spare parts resumed in 3Q01
- Shelf cleaning of zero time P/N 901 in process
• Field action plan for installed P/N 901 being evaluated
CFM56 Operators Conference – May 21 - 22, 2001 CFM Proprietary Data Unauthorized Disclosure Prohibited 8
New Outer Race Material
• 90% of failures confirmed to be initiated by outer race spalling
• Outer race material change from M50 to 32CDV13 deep nitriding
- Material structure more resistant to crack initiation
- Improved residual stress profile restricts crack / spall propagation
- Over 21,000 cycles completed with no failure during engine
ground tests
• Introduced on -5C production for Dec 01 A/C delivery
- Spare parts starting to be available for -5C
• Being introduced on other engine models for A/C delivery by July 02
More Resistant 32CDV13 Material for Outer Race Being
Introduced on All CFM Engine Models
CFM56 Operators Conference – May 21 - 22, 2001 CFM Proprietary Data Unauthorized Disclosure Prohibited 9
• CFM56-5C LPT installation tool modified
- Improved stiffness to keep perpendicularity between LPT shaft and case
- Already in place for other engine models
- All major -5C overhaul shops equipped with this new tool
• Overhaul shops Best Practices
- Assembly line and shop practices improvements identified on 1999
- Cleanliness / Preservation / Handling / Installation
- Bearing “Best Practices” CESM 009 issued on 1999 to shops in order to
highlight bearing handling and assembly practices
- Periodic meetings with overhaul shops to re-emphasize these
recommendations
Shop Improvements
Post Shop Visit Failures Being Reduced Since 99 Through
Best Practices Embodiment
CFM56 Operators Conference – May 21 - 22, 2001 CFM Proprietary Data Unauthorized Disclosure Prohibited 10
Monitoring System
• Algorithm to detect #4 bearing outer race distress with
existing engine vibration sensors has been developed
• Multiple use tooling
- Stand alone tool P/N 856A2679 available to screen engine
- For engine test cells ( G01 )
- All CFM production test cells have been equipped
- Major -5C overhaul shops are equipped
- For A/C ground run ( G02 )
- Tool validation achieved on March 02
- Airborne System
- Program launched with Boeing / VibroMeter
- SER to be started by July 02
- Not launched on Airbus applications as of today
Need to Gather Experience With
This New Monitoring Tool
CFM56 Operators Conference – May 21 - 22, 2001 CFM Proprietary Data Unauthorized Disclosure Prohibited 11
Monitoring System
N1
N2
No. 1 brg
FFCC/ TRF
Portable / Test Vibration Monitoring Unit
H (N2-N1)
Tool 856A2679
HP N2
BP N1
#4R detection
message
Accelerometer 1
Accelerometer 2
CFM56 Operators Conference – May 21 - 22, 2001 CFM Proprietary Data Unauthorized Disclosure Prohibited 12
Summary
• # 4 Bearing reliability on CFM56 fleet has been improving since 1999
- However, some variability between engine models, with highest rate on
CFM56-5C model
• Higher failure rate with P/N 901
- P/N 901 has not been installed on production engines or delivered as
spare parts since 3Q01
- Field action plan being evaluated
• More resistant 32CDV13 material for bearing outer race being
introduced on all CFM engine models
• Post shop visit failures have been reduced since 1999 through Best
Practices embodiment
• Monitoring system for engine test cell and A/C ground run is
available
- Need to gather experience with this new tool

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CFM56 Number 4 Bearing Status

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