CFM Components & Accessories Accessory GearBox Bearing Line #4

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CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 1
Accessory GearBox Bearing
Line #4
Components & Accessories
• Manufacturing Quality Issue
• New failure
CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 2
• 3 cases of metal particles retrieved in AGB/TGB MCD during routine inspection
 Low time failure phenomenon (failures occured on engines < 2500 H)
Handcranking
Pad
Ball Bearing
spalled
AGB
Housing
Background
• Subsequent investigation revealed AGB
handcranking pad gearshaft ball bearing
failure (AGB Line #4)
 Bearing outer race spalling
 Bearing P/N 340-052-602-0
 P/N 340-052-602-0 also installed on IDG
Gearshaft Bearing (AGB Line #8)
– no problem reported to date.
• Bearing P/N 340-052-602-0 also installed
on CFM56-3
No event reported to date
AGB line #4 Quality issue
CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 3
Investigation
• Three(3) failed bearings came from a single grinding batch
 incriminated batch includes 361 bearings
 73 CFM56-7B AGB’s in service equipped with P/N bearings 340-052-602-0
 15 bearings delivered as spare parts
AGB handcrancking aging repartition on -7B
1
21
16 16
6
7 7
5
1
0 2 4 6 8
10
12
14
16
18
20
22
24
0-500
500-1000
1000-1500
1500-2000
2000-2500
2500-3000
3000-3500
3500-4000
>4000
Hours
Number of AGB
1 Failure
2 Failures
Low time phenomenon < 2,500 EFH
AGB line #4 Quality issue
CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 4
Corrective actions
• Corrective actions have been implemented by vendor
 Production improvements dedicated to the grinding process :
Tool replacement
• Customer Communication released through Fleet highlite article
• SB 72-A0368 released May 28th, 2002 cat.3
 Replacement of Bearing P/N 340-052-602-0 at engine SV
opportunity for engines < 2500H since EIS
AGB line #4 Quality issue
CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 5
• One new event leading to IFSD
 heavy chips found in MCD
 Low time failure phenomenon (failure occured on engine < 1300 H)
• Investigation revealed AGB line#4 bearing failure
 Bearing P/N 340-052-602-0 outer race spalling
 Bearing not in the previous affected batch
Background
AGB line #4 New Failure
 Investigation results identified root cause
unusual Dendritic macrostructure which could
potentially affect the material characterisitcs
 Random phenomenon occuring due to
abnormal heterogeneous structure typical of
material coming from the end of the bar
 Quality investigation still in process with
supplier
No link with previous Issue
On condition view of
defective bearing
CFM56-7B WTT Meeting - September,26-27/2002 CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 6
Investigation results
location of transversal
cross section outer ring General view showing unusual dendritic structure at
mid portion compare to normal grain flow at each side
Abnormal heterogeneous structure with unacceptable dendritic appearance
likely more from casting material instead of hammered material
AGB line #4 New Failure

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CFM Components & Accessories Accessory GearBox Bearing Line #4