CFM56-7 HMU FMV / Resolvers

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February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 1
CFM56-7 HMU FMV / Resolvers
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 2
CFM56-7 HMU FMV / Resolvers
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 3
FMV Related Faults
• FMV faults have become leading cause of D&Cs in -7B fleet
- Fault codes 73-x034y, 73-x035y (x=Channel, y=Engine position)
- Faults result in Engine Control Light indication in cockpit
- Driving 10 HMU removals per month
- No operational events
• Extensive root cause investigation on-going
- Analysis, component, systems rig testing
• Design and manufacturing process changes are being
incorporated to address identified failure modes
• Additional changes for improved reliability being defined,
evaluated and tested
- Design, manufacturing, software logic
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 4
• HMU and resolver analytical efforts
- Tolerance studies, loads, modal, thermal effects including finite
element analysis
• HMU Testing at Burbank
- Run-as-received, electrical checks, inspections (wires, binding, wobble)
• Resolver Module Testing at Kearfott
- Room temperature electrical tests and thermal cycling (all)
- “Shake & bake” testing (10 units) - no failures observed
- Wire disassembly of unconfirmed units (7) - 2 rubbed rotors observed
FMV Root Cause Investigation - Scope
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 5
• Systems level testing on CFMI systems rig
- Focus on unconfirmed units
- Allows monitoring of individual windings and EEC faults
• HMU / Resolver Module Testing at Honeywell - South Bend
- Cell 8 rig test temperature and FMV cycling - 11 units
- Vibe testing for intermittent opens / shorts - 26 units
- Thermal and moisture tests of resolvers to check for shorts - 13 units
- Load testing for channel disagree faults - 2 units
FMV Root Cause Investigation - Scope
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 6
FMV Root Cause Investigation - Findings
• Fault confirmation rate currently 42%
- 74% resolver, 26% HMU-related
• Fault tree analysis used to identify 70 possible failure contributors
- 65 of these have been investigated
• Design and process improvements incorporated for 11 of 12 failure
modes identified to date
- Implemented in new production and field return units following
introduction
42%
58%
74%
26%
Unconfirmed Confirmed Resolver
HMU
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 7
0
2
4
6
8
10
12
14
16
Rotor Winging Open
Lamination Damage/Binding
Stator Termination Failure
Sator Winding Open
Insulation Resistance
Rotor Termination Failure
Resolver Position Adjusted
Wire Chafing
High Eng Play
Bent Connector Pin
Mis-pinned Connector
FMV Extension Wobble
End Play Stator Termination
Rotor Opens in
Winding and Near
Termination
Stator Winding
Open
Low Insulation
Resistance
Resolver Schematic
Resolver Failure Pareto
FMV Root Cause Investigation - Findings
• Majority of resolver failures
related to wiring issues
- Quality and position
adjustment lessor
contributors
• “Rotor winding open” to be
addressed 2Q’02
- Improved strain relief at
termination
- Wire gauge increase from 43
to 42 …currently being tested
Corrective Action in Process
Corrective Action In Place
No Corrective Action Defined
February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 8
• Corrective actions expected to address some but not all
unconfirmed units (58%)
- Non-resolver related problems suspected as majority of unconfirmed
population……..linkage, system stackup
• FMV linkage evaluations in process:
- Resolver ball hangup due to potential geometric stackup issue
- FVM extension wobble due to side loading of extension
- High friction/clamping force on ball follower due to wear
• Systems level analysis (Engine Control, HMU, wiring) being
performed to insure compatibility
- Potential cause for “out-of-range” faults
- Plans for acquiring EEC NVM data to support investigation are being
developed
• Additional changes being considered for improved reliability:
- Improved software accommodation logic
- Larger diameter wires (>42 gage) in resolver and resolver housing
change
FMV Root Cause Investigation - Findings

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CFM56-7 HMU FMV / Resolvers