CFM 737 N1/N2 Vibration Team Report

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Boeing and CFMI February 5, 2002 Proprietary Information
737 N1/N2 Vibration Team Report
2
Boeing and CFMI February 5, 2002 Proprietary Information
737 / CFM56-7B N1 Vibration / N2 Tone
• The current aircraft / engine vibration related noise / vibration
levels do not consistently meet customer expectations without
significant flight line disruptions
• Define / implement solutions with goal of B1/C1
• No quality impact
Problem Statement
Boeing / CFMI Team Charter
N1/N2 – 3P Team Status
3
Boeing and CFMI February 5, 2002 Proprietary Information
N2 Tone - 2001
• Ground Tone
• Not a major flight line cause disruption
• Can result in engine removals
• In-Flight Tone
• Not a problem since 10/99 S/W mod
• Slight increase squawk activity in summer 2001
0
10
20
30
40
50
60
70
80
J a n
M a r
M a y
J u l
S e p
N o v
J a n
M a r
M a y
J u l
S e p
N o v
Month
E n g in e S q u a w k R a t e - %
RTV Buttons
Squawk Rate
Repeat Squawk Rate
Flight Line N1 Vibe - 2001
Flight Line N1 Vibe Squawk Rates
•Major flight line disruption cause
• Low N1 vibe levels required to support delivery
• Challenging VENOS (interior noise/vibe) delivery criteria
• RTV/ Buttons have improved situation
• Squawk / repeat squawk rates still unacceptable
• AVM Solution / Fan Trim typically resolves squawks
• Repeat squawks result in retrim, fan blade relube or
engine removal
Engine Vibe Related Squawk Distribution
June to Sept 2001
7%
13%
77%
3%
N1 AVM> 1.0
N1 AVM > 1.0 &
A&T
N1 A&T
N2
N1 A&T Major
Cause of Squawks
2000 2001
N1/N2 – 3P Team Status
4
Boeing and CFMI February 5, 2002 Proprietary Information
Purpose:
• -599 /Airplane Inst’l Effects
• Optimized Balance Process
• Determine Aircraft/Engine sensitivity to unbalance
• Airplane Loading Impact / Flight maneuver effects
Key Findings:
• LPT unbalance verified / correct w/ 2-Plane trim
• Quantified sensitivity to Fan/LPT unbalance
• TRF sensor is better indicator of LPT unbalance than FFCC
• Impact of fuel and airplane loading measured
Production A/P Flt Test
Eng -599 on YA106
Strut Shake Test
YA106 ‘GVT’
Purpose:
• Data to Develop Math Model for
Airplane A&T prediction
• Use to identify and evaluate fixes
Key Findings:
• Strut structure resonances found in
N1and N2 ranges
Eng -599
Investigation at CFMI Test Cell
Purpose:
• Compare Fan/LPT unbalance vs On-wing
• Investigate LPT unbalance source
• Quantify improvement to #5 ODB mod
Key Findings:
• Balance solution test cell vs. on-wing similar
• High LPT unbalance confirmed
• Not typical of current manufacturing process
• Process change implemented to prevent reoccurrence
• #5ODB testing scheduled Feb-Mar 20002
Solution Development Test
YA106 (phase 2)
Purpose:
• FCSB / Fairing / Strut Transmissibility Test
• Local N1 Treatment and Passenger Load Testing
Key Findings:
• Fuel loading has significant impact
• N1 Tone reduction FCSB possible – testing TBD
• Proposed N1 treatment not effective
• Investigating new configuration
N1/N2 – 3P Team Status
5
Boeing and CFMI February 5, 2002 Proprietary Information
3D MWFan Blades
• Proceeding with immediate implementation of
the following three solutions
• 2 Plane Trim Balance (CFMI test cell)
• 3D MW Fan Blades (CFMI new production)
• Improved AVM Balance Algorithm (New A/Ps)
• Assess flight line benefit for
• N1 AVM, N1 Audible, N1 Tactile
2 Plane Trim Balance (LPT Balance) Improved AVM Balance Algorithm
• Currently fan blades mapped for radial moment weight (MW)
only
• New procedure allows blades to be mapped for radial,
tangential, and axial fan blade MW at new engine delivery
• Results in fan blade sets with lower fan unbalance
- Expect improvement in ability to trim balance engine to
achieve lower vibe levels consistently
- Minor improvements in N1 AVM and A&T
• Intro at CFMI test cell Jan 2002
• No field impact regarding fan blades & procedures
• Fan trim balance performed to reduce N1 engine vibe
levels and N1 A&T
• Currently assessing benefit of 2 plane trim balance
for N1 A&T levels and flight line disruption rate
• 2 plane trimmed (as req’d) at CFMI starting 888-769
• Flight line evaluation in progress
• Go-Forward plans - April, 2002
• CFMI All OPS Wire issued Dec 2001
• S/B 72-0347R1 introduced LPT Stage 4 clips
• Procedure not intended for in-service use
• Improve quality of data collected for fan trim solutions
• Speed ranges
• Stability requirements
• Coefficients
• Reduce A/P noise and vibration and AVM levels
•Improved ability to resolve squawks at >95% N1
• Available on production AVM units Q2 2002
• Retrofit not required, but available
Category 1 Solutions
N1/N2 – 3P Team Status
6
Boeing and CFMI February 5, 2002 Proprietary Information
Other Solutions Being Considered
• #5R Oil Damped Bearing Optimization
• Local Airplane Treatment for N1
• Fan Blade Break-in
• Optimized Fan Cowl Support Beam
• #3R Bearing Clearance
• Optimized Interior Modification for N2 tone
• AVM and VENOS Measurement and Criteria
• Active Vibration Control
N1/N2 – 3P Team Status
7
Boeing and CFMI February 5, 2002 Proprietary Information
Summary
• Engine related N1 / N2 vibes are major flight line disruption cause
• Boeing / CFMI team charted to implement solutions to achieve B1 / C1 goal
• No quality impact
• Category 1 solutions being implemented / evaluated - 1Q2002
• No in-service impact
• Other potential solutions being considered - 4Q2002
N1/N2 – 3P Team Status

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