CFM Radial Drive Shaft Failure

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Radial Drive
Shaft Failure
CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 2
• 8 RDS failures on -5B model since December 2000
- Engine TSN below 3000 FH
- 6 IFSD’s, 2 UER’s from MCD particle findings
• All engines included in the last 300 produced CFM56-5B’s
Fleet experience
Date ESN TSN CSN Event Findings / status EMCD /
screens
05/03/98 779165 5003 3613 IFSD Brg spall ; hvy damage ;no cause found No report
19/12/00 779873 245 119 IFSD Brg spall ; hvy damage ;no cause found M50+RBD
12/04/01 575120 436 360 IFSD Brg spall ; hvy damage ;no cause found M50+ RBD
16/03/01 779972 671 454 UER IR+roller spall ; outer housing sector indic M50
11/06/01 779809 2038 1183 IFSD Brg spall ; shaft damaged ; not investigated no report
08/07/01 779996 256 177 IFSD 6:00 frame strut crack ; not investigated no report
17/07/01 779983 1151 546 IFSD 6:00 frame strut crack ; not investigated no report
Post SB 72-0407 19/11/01 575128 2726 800 UER EMCD popped out M50
event
CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 3
Hardware description
#6:00 Fan
frame strut Outer housing
Inner housing
Radial Drive Shaft
(RDS)
Transfert Gearbox
(TGB)
Roller
bearing
Washer
Vespel
nut
Inlet Gearbox
(IGB)
Fan frame
CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 4
Root Cause Analysis
• Major contributor
- Assembly tooling used for inner housing bonding
- Tooling overtorque generates housing
ovalization
- Randomly distributed
- Reduces clearance between housings…roller
pinching
- Aggravated when in same direction than normal
thermal deformation of fan frame bore.
- Problem induced by production line organization
change initiated early 1999
CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 5
Root Cause Analysis
Engine centerline
Outer race spalling due
to roller pinching
Reduced roller
clearance
CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 6
• Minor contributors
- Glue change for outer housing bonding in Feb 99
- Loctite 932 replaced by Loctite 638 (structural glue)
- Fan frame bore ovalization
- Discrepancy between both manufacturing sources, although within
tolerance
Root Cause Analysis
CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 7
Corrective Actions - Production Level
• Tooling modified
- Eliminates overtorquing
• 100% housing ovalization check
• Loctite 932 glue re-introduced
- Conservative measure
CFM56 Operators Conference – May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 8
• Affected population defined
- Engines below 5000FH
- SAC: 779522 to 779899 and 575101 to 575261
- DAC: 779900 to 779999 and 575900 to 575901
• On-wing ECMD inspection: SB 72-0407, cat 2, Oct 2001
- Pop-out indication, inspect MCD per AMM within 10 cycles
• Engine induced in shop before 5000 FH
- Inspection per SB 72-0409, cat 3, Nov 2001
- Inner housing diameter ovalization check
- Housing/bearing replacement if ovalization out of tolerance
- Engine relieved from SB 72-0407
Corrective Actions - Field Level

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CFM Radial Drive Shaft Failure