CFM Aft Engine Mount Center Link

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CFM Aft Engine Mount Center Link

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CFM Aft Engine Mount Center Link

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CFM Aft Engine Mount Center Link

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CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, February 2002 WTT face to face or Export are Prohibited
Aft Engine Mount Center Link
Gary Morriss
Boeing Service Engineering
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, February 2002 WTT face to face or Export are Prohibited
Aft Engine Mount Center Link
• Background:
 The aft engine mount contains a
center link which secures the aft
mount to two center TRF lugs.
 Center link is boomerang-shaped
and almost symmetrical from left
to right.
 Two operators found a total of 7
engines with a reversed center
link.
– All cases were found after
aft mount overhaul.
 Reversed center link locates aft
engine 0.174 inches to the right.
 Condition not related to new
production.
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, February 2002 WTT face to face or Export are Prohibited
• Actions Completed
 Fleet communication
– 737NG / CFM56-7B WTT F2F Meeting Presentation (Feb ‘02)
– Boeing Fleet Team Digest Article 737ng-FTD-71-01003, dated 20
Dec ‘01
– Fleet Team Emerging Issues No EM-02-00018, dated 17 Apr ’02
 Maintenance documentation changes
– Revised AMM, CMM, and PPBM to clarify assembly (1Q ‘02)
 Agency Communication (FAA and DGAC) - No immediate concern
– Boeing Agency Letter (15-Apr 2002)
– CFMI Agency Letter (18-Apr ‘02), CFMI JTM (4-Jun-’02)
 Boeing Engineering Investigation Board - Safety SRP identified (May ‘02)
– Determined requirement for Boeing Alert Service Bulletin
Aft Engine Mount Center Link
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, February 2002 WTT face to face or Export are Prohibited
• Action Completed (cont)
 Alert Service Bulletin
– SB 737-71A1462 released on MyBoeingFleet 15 August 2002 and
dated 29 August ‘02.
 Turbine Rear Frame Life Assessment on all reported TRF’s
– TRF P/Ns 340-166-205-0 and 340-166-206-0 - no life impact for
SAC operation
– TRF P/N 340-027-113-0 - analysis in process, ECD mid-
September ‘02
Aft Engine Mount Center Link
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, February 2002 WTT face to face or Export are Prohibited
Marking of
Hanger Fitting
and Center
Link
Aft Looking
Forward
• Action Plan to Prevent Misinstallation
of Center Link
 Proposal to part-mark center
link and aft mount hanger
fitting.
 Results in new part number for
aft mount assembly and center
link.
 Design change decision
September ’02
 SB to retrofit aft mounts inservice
– status TBD
– Propose to vibro-engrave
markings on existing aft
mounts.
Aft Engine Mount Center Link