CFM Fan Stator Module Booster Vane Corrosion

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CFM56-7B WTT Meeting - September,25-26/2002 CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 1
Booster Vane Corrosion
Fan Stator Module
CFM56-7B WTT Meeting - September,25-26/2002 CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 2
Background
 Several reported cases where steel booster vanes were found with pitting
corrosion marks
– Heavy corrosion marks outside of current AMM/ESM limits
– Other CFM56 engine models affected
Engineering assessment
 Root cause investigation - Completed
– Booster vane material 17-4PH is sensitive to corrosion
 Specific saline operation environment is an aggravating factor
 Potential impact on booster vane durability
– Calculations predict a risk to initiate a crack from pits then propagate in HCF
mode into base material
– No concern in-service
 No crack finding reported to date
 Outer shroud attachment area (bolt holes) is most critical area
 Service Evaluation on-going on a CFM56-3 to better assess progression of
pitting corrosion phenomenon during engine operation - No findings to date
Fan Stator Module
Booster Vane Corrosion
CFM56-7B WTT Meeting - September,25-26/2002 CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 3
1 mm
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Fan Stator Module
Booster Vane Corrosion
CFM56-7B WTT Meeting - September,25-26/2002 CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 4
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Fan Stator Module
Booster Vane Corrosion
CFM56-7B WTT Meeting - September,25-26/2002 CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 5
Corrective Action Plan
 New serviceable limits being implemented in the AMM, and ESM
– AMM Limits
 Any amount of surface oxidation, pitting or corrosion marks on Stage
1, 2, 3, and 4 Booster vanes is permitted.
– ESM Limits
 At module Level
» Any amount of surface oxidation, pitting or corrosion marks on
Stage 1, 2, 3, and 4 Booster vanes is permitted.
 At piece part level
» Stage 1, 2, 3, and 4 Booster vanes outer & Inner shrouds. Any
number if less than 0.02” (0,5 mm) Max. Length.
» Stage 1, 2, 3, and 4 Booster vanes outer & Inner shrouds welds.
Any number if less than 0.008” (0,2 mm) Max. Length.
» Stage 1, 2, 3, and 4 Booster vanes airfoils. Any number if less
than 0.012” (0,3 mm) Max. Length.
Fan Stator Module
Booster Vane Corrosion
CFM56-7B WTT Meeting - September,25-26/2002 CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 6
Corrective Action Plan (cont’d)
 Rework under study
– Addition of a protective paint, or passivation
 Request certification configuration
modification
 Service Evaluation on-going on CFM56-3
engine
 Expected to be available 1Q 2003
Fan Stator Module
Booster Vane Corrosion

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CFM Fan Stator Module Booster Vane Corrosion

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eptember,25-26/2002 CFMI / Boeing Pro