CFM56-7 N1 Vibration

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CFM56-7 N1 Vibration Contents: • Qualification and Production Experience -Development and Certification -Production Engine Test Cell • In-Service Vibration Team CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 3 CFM56-7 Vibration Signature for FAN Unbalance FFCC 0.00 5.00 10.00 15.00 20.00 25.00 30.00 0 1000 2000 3000 4000 5000 6000 LP Speed - RPM Displacment - Mils DA Endurance Dwell 107 cycles, 32 hours 27 mil (+5 units) Typical production level Maintenance Guidelines Test Cell Limit 0 AVM Units 5 N1 Vibration Endurance with Full 737NG Propulsion System CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 4 CFM Production - Fan Trim Balance • Vibration levels during production acceptance test - #1Brg, FFCC max LP vib level < 2.5 mils prior to delivery - Additional balance performed to achieve low level (~1 mil) at Boeing flightline • Fan trim balance conducted by recording LP vib amplitude & phase response during vib survey (slow accel, decel) or with steady-state dwell points • Balance achieved by spinner screw weight changes - 36 holes in aft spinner, 7 different screw sizes - Provides full range of adjustments In-Service Vibration Team CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 6 N1 Vibration Team Objective • In May 2000 CFM/Boeing and six airlines completed a study of in-service N1 vibration • 737NG operators reported increasing N1 vib levels and/or N1 vib shifts following trim balance. • Operators also expressed concern on maintenance guidelines and recommendations • CFM reviewed the engine vibration levels, balance history, and pilot / maintenance crew reports for a fleet size of 240 engines, comprising ~2000 flight legs during a four month period. CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 7 In-service N1 Vibration Levels > 1.5 AVM Units or Tactile Vibes and Not Resolved With Current AMM Procedures Manpower Vibration Measurements Flight Environment LP Rotor Hardware HIGH Ranked Causes Cause & Effect Analysis What is about ＃. Fan Blade Seating Delivery Vib Levels Crew Training # Engine Cycles ACARS Data Collection LPT Blade Loss Icing Balance equipment Wide Chord Blade Flight Crew Reports Airplane Delivery Platforms Engine thrust rating AMM Procedures Guidelines FOD # Engine Hours Platform Seals Blade Lubrication Trim Balance Method Flightdeck display AVM Data Collection CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 8 N1 Vibration Status Background • Vibration variation impacts trim balance effectiveness • N1 Vibration is not common but has been reported inservice - Customers perform trim balance using AVM / relube at ~2 units - Effective in reducing vibration to less than 1 unit CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 9 N1 Vibration Status • Identified 2 prime factors for N1 vibe variation - Vibe variability due to blade / disk seating - Improved with G-n paste lube, introduced 05/00 in production - CESM 005 provides lubrication recommendation for N1 vibes - Vibe variability due to blade axial movement in disk - Creates a dynamic unbalance couple - Engine sensitive to dynamic unbalance couple - Elastomer buttons introduced to retention ring - May 2001 CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 10 Elastomer Buttons Rubber Button Aft View of Retention Flange Disk Spacer Retention Flange Blade Platform Retention Ring • Button installed in current holes in retention ring - limits blade axial travel - Easily retro-fittable • S/B 72-325R1 introduced Elastomer Buttons - May 2001 CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 11 N1 Vibration Team Conclusions CESM 007 Recommendations: • Schedule fan trim balance when N1 vibration trend levels are above 1.5 每 2.0 units • Lubrication fan blades and disk slots provides benefit for reducing engine vibration levels. The re-lubrication method / timing is documented through CESM 005. • The recommended format for reporting N1 vibration related issues is included as an attachment to CESM 007.§ CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 12 Summary of Fleet Experience • Typical engine vibration level at airplane delivery ~ 0.5 unit • N1 vibration level in-service average ~ 1.1 unit with various levels of trim balance activity • N1 vibration level increase 0.4 unit for every 2500 hrs (on average) • SAGE cruise trend data ~ 35% lower than max AVM flight history data levels • Threshold for crew reports of increased ~2 units vibration and/or airplane tactile vibration • Typical vibration reduction from AVM trim ~ 1.0 每 1.5 units balance • Engines identified with difficulty to be maintained 3 engines (vib level increased within ~ at low vibration levels 1 month after fan balance) • Fan blade re-lubrication Provides benefit in reducing / maintaining N1 vibration levels LP Vibration Team Findings CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 13 Other Contributors to Vibration - Fan Blade Platform Balance Weights vary in size Not All Fan Blade Platforms require a Balance Weight •The loss of fan blade platforms seals or balance weights can contribute to engine unbalance •Field experience revealed an immediate 1 to 2 unit increase N1 indicated vibration when a balance weight or platform seal is missing •Maintenance manual revised recommending platform seal lubrication before installation Platform Seals CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 14 • Currently evaluating benefit of 2 plane trim on CFM56-7B - Fan trim balance performed to reduce N1 engine vibe levels and N1 audible noise and tactile vibration (A&T) - Currently assessing benefit of 2 plane trim balance for N1 A&T levels - 2 plane trimmed (as req＊d) at CFM starting December, 2001 GE 888- 769, SN 889-854 and up - Boeing Flight line evaluation in progress - CFM All OPS Wire issued Dec 2001 - S/B 72-0347R1 introduced LPT Stage 4 clips - Test Cell Experience - TRF Vibes 1.69 => 1.28 mils avg, LPT unbalance 250 => 100 gm-cm avg (75% engines receive clips) 2 Plane Trim Balance Evaluation - Production Engines CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 15 • It is not intended that Operators will perform two plane trim balance in-service - CFM56 experience shows that CFM56-3 operators did not perform two plane trim balance in-service. - Two plane trim balance on the CFM56-7B is more complicated due to the longer exhaust nozzle making clip installation more difficult • There is no action recommended or required for inservice CFM56-7B engines delivered with LPT balance clips - If clips are observed to be missing in-service, it is not necessary to reinstall the clips - If clips are observed on an LPT at overhaul, it is recommended to leave clips installed unless LPT module balance is to be conducted 2 Plane Trim Balance - In-Service Engines CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 16 Summary • CFM56 Production engines are delivered with vibration levels less than 2.5 mils DA - typically ~ 1.0 mils DA - Engine durability demonstrated at vibration levels over 5 units • N1 Vibration team formed which included six airline customers - Conclusions from the team are published in CESM 007 - Performing periodic trim balances in addition to lubricating fan blade roots and fan disk slots is a effective method for retaining low LP vibration levels CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 17 Summary (Continued) • Additional actions taken: - Introduced new fan blade lubrication into production process May 2000 (GN Paste) - Introduced elastomer buttons into production May 2001 to limit fan blade axial travel - Improves N1 vibration variation - Evaluating the benefits of 2 plane balancing on production engine deliveries at Boeing flight line to improve airplane comfort Engine Vibration Is Not Being Reported As an In-service Issue Back-up Material: Engine Airborne Vibration Monitoring System CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 19 CFM56 Vibration Sensors FFCC (-7, -5C) TRF (-2,-3,-5A,-5B ) CFM56-7B # 1 Brg (all) CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 20 737 Classic vs NG General Info Classic NG Engine CFM56-3 CFM56-7B Fan Blade Design Mid Span Shroud Wide Chord Engine Bearings 1B,2R,3B,4R,5R(ODB) Same, but also 3B+3R Isolators Fwd & Aft Mts, T/R None AVM Scale 0-5 Units (20 mils DA) Same Vib Sensors # 1 Brg and TRF #1 Brg and FFCC N1 Vibration Engine Balance Provision FAN and LPT Same Flight Line Trim Process FAN/LPT trim with in-flt data Fan trim using in-flt data N1 Vibe Peaks Hold and Climb (max) Same Vibe Endurance 21 mils da (+5 units) 27 mils da (+5 units) Maintenance Levels 7-10 mils da (3 units) Same Advisory Levels 14-15 mils da (4 units) Same Test Ship Limit 2.5 mils da 2.5 mils da Test Avg Level 1.5 mils da 1.0 mils da Overhaul Shop Limit 2.5 mils da 2.5 mils da CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 21 CFM56-7 LP Vib Response Characteristics (before trim balance) * Response peaks at 3000 rpm and 4200 - 5200 rpm (similar to CFM56 family) * Engine easily fan trim balance to low levels for improved comfort #1Brg FFCC Peak at ~3000 rpm Near hold power Peak at 4200 - 5200 rpm Climb and cruise range CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 22 737NG / CFM56-7 AVM Functions • AVM System Functions - Display engine vibration 1/rev N1 and N2 levels in flight deck - Record engine vibration flight history data - Record engine LP rotor balance data, calculate trim balance solutions • AVM System Description - 2 accelerometers per engine (#1Brg and FFCC) - LP and HP rotor speed signals, each engine - 1 AVM signal conditioner per airplane - Two vibration indicators in flight deck - 1 indicator for each engine - CDS displays 1 value, max level (in units) of 4 parameters - Max of #1Brg or FFCC, fan/rev or core/rev vib level CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 23 AVM and AMM Terminology • ※Fan§ Number 1 Brg sensor N1 Vibration - Sensitive to fan unbalance • ※HPC§ Number 1 Brg sensor N2 Vibration - Sensitive to HP rotor unbalance • ※HPT§ FFCC N2 Vibration - Sensitive to HP rotor unbalance • ※LPT§ FFCC N1 Vibration - Sensitive to fan and LPT unbalance CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 24 AVM Balance Method • AVM Monitors #1Brg, FFCC response continuously during flight • Stores up to 6 balance data points based on speed ranges, stability criteria • Stored balance data used post-flight to provide balance solution • AVM box provides recommendations for spinner wieght change to balance engine 6 AVM defined speed ranges for balance data collection Typical #1Brg in-flight response AVM stored balance data 1000 2000 3000 N1 Spe4e0d00 5000 1.2 327 1.1 5 0.9 63 0.8 53 0.5 57 0.7 49 1.6 20 1.5 36 1.1 82 1.2 64 0.8 19 0.5 51 Speed Range %N1 Fan (mils / degrees) LPT (mils degrees) 1 2 3 4 70 65 5 6 95 90 85 80 Location Remove Install 27 P02 P05 28 P05 P06 29 P02 P06 32 P07 P05 AVM provides straightforward instructions for balance screw changes CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 25 737NG LP Vibration AVM Scales 0.0 1.0 2.0 3.0 4.0 5.0 AVM Scalar Units #1Brg -- mils DA #1Brg (-113, -213) #1Brg (-114) 0. 5. 10. 15. 20. 0.0 1.0 2.0 3.0 4.0 5.0 AVM Scalar Units FFCC -- mils DA FFCC (-113, - 213) FFCC (-114) • AVM scales changed with introduction of -114 AVM (Oct ＆99) • Provides same scaling for both sensors for LP vibration • 1 unit = 2.5 mils DA (CFM ship limit at production, overhaul) • At recommended maintenance levels •Same scaling for #1Brg (-113, -213, -114) •Slightly more conservative for FFCC with -114 • No change in max scale values ( 5 units = 20 mils DA) • Refer to Boeing Service Letter 737-SL-77-015-C for additional AVM details 0. 5. 10. 15. 20. Typical delivery levels Recommended maintenance levels Typical delivery levels Recommended maintenance levels CFM56 Operators Conference 每 May 21 - 22, 2002 CFM Proprietary Data Unauthorized Disclosure Prohibited 26 AMM Procedures - Current Vibration AMM Recommendations 1- Vibration Guideline AMM 71-00-00 • If indicated vibration levels are between 3 and 4 units : action at airline policy • If indicated vibration is above 4 units with other parameters Normal perform the following: a/ Routine inspection FIM 71-05 (FOD＃) b/ AVM download: engine removal if vibs source is N2 engine trim balance if vibs source is N1 note: refer to Boeing Fault Isolation Manual Chapter 71-05 2- Maintenance Manual Current trim balance method • The Three shot plot procedure AMM 71-00-00 ( test 14A) Preferred method • The On Board Procedure AMM 71-00-00 ( test 14B)

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CFM56-7 N1 Vibration

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CFM56-7 N1 Vibration