CFM Booster spool lugs

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CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
Booster spool lugs
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
Booster lug
¡E BACKGROUND
č OVERVIEW OF CONCERNED AREA
BOOSTER LUG USED FOR PLATFORM ATTACHMENT
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
Booster lug
¡E BACKGROUND
č Lug liberation encountered during rig test
¡V Test conducted for platform modification substantiation
¡V Lug failure after 18374 cycles.
¡V Parts not completely representative of production (Hole shot
peening)
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
Booster lug
¡E BACKGROUND
č Field experience
¡V PCA engine (SWA 7733 hours/6145 cycles) inspected.
„X Mark area with light fretting surrounding each hole.
„X Visual inspection, FPI and ECI within the hole
revealed no finding/no indications.
„X 3 lugs found with surface micro-crack on contact
surface
. 1 crack of 0.5mm (0.02 inch) found through detailed
microscope inspection (not detectable by ECI)
. 2 cracks of 0.8mm through ECI
. All cracks located in fretting area on the contact
surface at about 3o¡¦clock
¡V Engine 875- 297( 4642 hours/2150 cycles)
„X no finding after ECI within the hole
¡V Engine 874-163 (6401 hours/6164 cycles)
„X no finding through ECI inspection
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
Booster lug
¡E BACKGROUND
č Development engine test experience : fleet leader
booster spool ~9550 cycles
¡V ECI within the hole , FPI and visual inspection revealed
no indications
¡V Spool used to run 90 000 cycles rig test
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
¡E ENGINEERING INVESTIGATIONS
č Comprehensive program performed to confirm root
cause and define short term (field plan), intermediate
fix in production and long term redesign
¡V Finite element model analysis
¡V Rig testing: 4 rig tests performed
rig number
accumulated
cycles speed
booster configuration
1 18 374 +10% of the RL radial load levels
flange not completely representative of
field configuration
2 21 626 redline
booster spool representative of field
configuration
3 90 000 redline
pizza pie configuration:field
configurations and improvements
4 46 504 redline
PCA booster
pizza pie configuration:field
configurations and improvements
Booster lug
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
¡E ROOT CAUSE
č Analysis shows that the damages are related to flange
bending leading to crack initiation and propagation.
centrifugal load from platform results in:
¡V High bending stress
¡V Bending and associated relative displacement results in
fretting in contact surface in high stressed area (lug forward
contact face)
č Damage only related to LCF loading. No HCF stress in this
area (measurement performed during engine development
test)
Flange bending
Booster lug
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
¡E FAILURE CONSEQUENCES
č Rig tests , specimen tests and calculation show that
crack propagations lead to lug outer parts failure and
platform liberation.
¡E The prime integrity of the booster spool is not affected.
Lugs are not part of the prime load carrying rotating
structure
Outer part
Inner part
Booster lug
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
¡E FAILURE CONSEQUENCES (con¡¦t)
č If platform liberation occurs, liberated hardware
containment has been demonstrated through
¡V Trajectory and energy analysis
¡V During development test with complete platform
liberation.
„X Large bird ingestion test
„X Fan blade out test
Booster lug
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
¡E IMPROVEMENTS
č Counter-weight installation :
¡V Counterbalance moment due to platform centrifugal load
Minimize flange bending
Booster lug
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
¡E CORRECTIVE ACTIONS
č Field plan
¡V Counter-weight installation at next fan blade lubrication
opportunity
„X Counter-weight installation before 7000 cycles
. No on wing ECI inspection required at installation
. Mandatory inspection required above 15000 cycles,
not to exceed 20000 cycles (one time)
„X Counter weight installation after 7000 cycles
. On wing ECI inspection required at installation
„X Parts with ECI indications :Over-serviceability to be defined
„X Mandatory inspection required above 15000 cycles, not to
exceed 20000 cycles (one time)
¡V Counter-weight installation to be performed no later than
11000 cycles
¡V SB 72 0296 for counter weight installation and SB 72
0295 for lug ECI
Booster lug
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
Booster lug
¡E CORRECTIVE ACTIONS
ƒç Field plan (cont¡¦d)
¡V Inspection thresholds
ECI at counter
weight installation
ECI beween 15 000 cycles
and 20 000 cycles
if counter weight installed since new no no
if counter weight installed before 7000 cycles no yes
if counter weight installed after 7000
cycles and before 11 000 cycles
yes yes
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
¡E CORRECTIVE ACTIONS
č Production
¡V Interim action for production
„X Introduction of counter weight until thickened
flange available
„X No inspection required for this configuration
(minimum initiation life 37 000 cycles)
¡V Final fix
„X Introduction of thickened lug
Booster lug
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
Field solution and intermediate production solution:
Lug with counter weight
Fix for production
reinforced lug
Booster lug
CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, December 2000 WTT face to face or Export are Prohibited
Booster lug
¡E SCHEDULES
č Interim action for production
¡V CAD in review at the agencie
¡V SB 72-0295 &72-296 in process
„X counter-weight available for production and field-
December 2000.
č Final fix with thickened lug
¡V First part available 2nd quarter of 2001

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CFM Booster spool lugs

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