CFM56-5B No 3 Bearing Review for Alitalia

瑤諾楷桶衾 2011-4-23 10:45:32

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CFM56-5B No 3 Bearing Review for Alitalia Pete Gruber CFM56 Product Support Engineering October 3, 2002 CFM56 No. 3 Ball Bearing Experience • No 3 Bearing Reliability 每 CFM56-5B Reliability 每 CFM56-7B Reliability • CFM56 Ball Cracking/Spalling 每 Winsted Non-Tumbled Population • CFM56 Bearing Skidding Investigation • ESN 575-175 UER Findings • ESN 779-129 IFSD Investigation • Summary CFM56 No. 3 Ball Bearing Reliability September 2001 thru August 2002 Summary of #3 Bearing failure rates on all CFM56 Engine programs No. 3 Bearing reliability staying at the same level over last 1-2 years 2001-2002 Bearing Failure Modes: • CFM56-3 Hard Particle Contamination 每 Control Program in place to control IFSD＊s per S/B 72-923 • Ball Residual Tensile Stress - Ball Cracking 每 UER＊s from ball cracking - Corrective Actions Implemented • Ball Spalling - Other Manufacturers and Lots • Ball Skidding 每 Recently observed on 每5B/-7B UER's IFSD's Hours UER Rate IFSD Rate CFM56-2A 0 0 0.123 0.000 0.000 CFM56-2B 1 0 0.747 1.339 0.000 CFM56-2C 0 0 0.321 0.000 0.000 CFM56-3 8 3 9.484 0.844 0.316 CFM56-5A 0 0 2.359 0.000 0.000 CFM56-5B 4 1 2.674 1.496 0.374 CFM56-5C 2 0 3.433 0.583 0.000 CFM56-7 3 1 5.915 0.507 0.169 Total 18 5 25.057 0.718 0.200 Note: Rates are per Million Engine Flight Hours Continued good reliability Last UER was in June, 1996 Recent events under investigation Overall excellent reliability M50 Bearing Recent UER＊s 每 2 of 3 were Alitalia 每 Two caught via Electronic Chip Detector • Both of these failures show signs of skidding 每 One Failure was an IFSD • Failure investigation in progress CFM56-5B No. 3 Ball Bearing Reliability CFM56-5B No. 3 Ball Bearing Reliability 12 Month Rolling Average 0.000 0.500 1.000 1.500 2.000 2.500 3.000 J-98 M-98 M-98 J-98 S-98 N-98 J-99 M-99 M-99 J-99 S-99 N-99 J-00 M-00 M-00 J-00 S-00 N-00 J-01 M-01 M-01 J-01 S-01 N-01 J-02 M-02 M-02 J-02 Date Failure Rate (Events per Million EFH) UER Rate IFSD Rate EIS March, 1994. No bearing failures prior to January, 1998 Current UER Rate - 1.518 UERs/MEFH Current IFSD Rate - 0.379 IFSDs/MEFH 12 Total Bearing Failures in 8.59 MEFH/5.51 MEFC since Entry into Service IFSD Rate is Improving Have experienced failures from different failure modes 每 Ball Cracking - Residual Tensile Stress 每 Single Ball Spall - Root Cause not determined 每 Ball Skidding - Very recent finding CFM56-5B Failures since EIS Engineering Team working to understand recent ball skidding experience Event Date Prod or O/H ESN Customer IF SD UER Brg TSN Brg TSV Bearing P/N Brg S/N Engine Delivery Date Last MCDI Oil Type Win sted Po p u latio n Investigation Findings 8-Feb-98 Prod 779-273 Leisure Air X X 3051 3051 1460M52P03 FCAA6326 May-97 28 Hours No No Root Cause Established 3-Feb-99 Prod 779-375China Eastern X 1792 1792 1460M52P03 FCAB1135 Jun-98 ECD Mobil Jet 2 Yes Residual Stress 12-Jun-00 Prod 779-465 US Air X X 4610 4610 1460M52P03 FCAB3909 Mar-99 ECD 2380 Yes No Root Cause Established 14-Nov-00 Prod 779-682 US Air X 2640 2640 1460M52P03 FCAB7702 Feb-00 ECD 2380 Yes Residual Stress 5-Feb-01 Prod 779-513 Iberia X X 4095 4095 1665M98P02 MDAGJ573 May-99 ECD Mobil Jet 2 No No Root Cause Established 20-Jul-01 Prod 779-573 US Air X X 3826 3826 1460M52P03 FCAB5476 Aug-99 ECD Visual 2380 Yes No Root Cause Established 25-Jul-01 Prod 779-721 Air Jamaica X 3621 3621 1460M52P03 FCAB8097 May-00 ECD Yes Residual Stress 11-Aug-01 Prod 779-968 Sabena X 2155 2155 1460M52P03 FCAB9910 Oct-00 ECD Mobil Jet 2 No Ball Crack 22-Dec-01 Prod 779-740 Air 2000 X 1732 1732 1460M52P03 FCAB8104 May-00 ECD Yes Residual Stress 3-Apr-02 Prod 575-175 Alitalia X 1318 1318 1665M98P02 MDAJC205 May-02 ECD No Ball Skidding 11-Jun-02 Prod 575-902 Finnair X 916 916 1665M98P02 MDAJN696 Jan-02 ECD No Ball Skidding 30-Jul-02 O/H 779-129 Alitalia X X 3612 3612 1460M52P03 FBGE3623 N/A ECD No NEED TO CONFIRM #3 as ROOT CAUSE Three low time failures 每 Two caught via Magnetic Chip Detector • One UER show signs of skidding • One UER for M50 每 Single Ball Spall 每 Not from Winsted Non-Tumbled Population 每 One Failure was an IFSD • Failure investigation in progress • Strong evidence shows advanced stages of skidding CFM56-7B No. 3 Ball Bearing Reliability Overall No 3 Bearing Reliability excellent 5 Total Bearing Failures in 14.96 MEFH/7.80 MEFC since EIS Recently experienced ball skidding on two events 每 Currently under investigation Recent CFM56-7B Failures Engineering Team working to understand recent ball skidding experience 0.000 0.250 0.500 0.750 1.000 J-01 F-01 M-01 A-01 M-01 J-01 J-01 A-01 S-01 O-01 N-01 D-01 J-02 F-02 M-02 A-02 M-02 J-02 J-02 A-02 Date Quantity of # 3 Bearing Failures/MEFH CFM56-7B No. 3 Ball Bearing Reliability 12 Month Rolling Average Current UER Rate - 0.507 UERs/MEFH Current IFSD Rate - 0.169 IFSDs/MEFH UER IFSD Event Date ESN Cust IFSD UER Brg TSN Last MCDI Oil Type Winsted Population Investigation Findings 17-Dec-01 877-205 Korean X X 3262 424H/377C 2380 No Ball Skidding 1-May-02 889-331 GOL X 3136 Normal MCD Insp Aeroshell 560 No Ball Skidding 5-Jun-02 877-419 Ryan Air X 5527 Normal MCD Insp Mobil Jet 254 No Single Ball Spall w ith Ball Crack - Root Cause under Investigation 37 36 28 32 62 85 113 131 97 99 95 80 18 17 13 7 7 1 3 0 0 20 40 60 80 100 120 140 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 19000 20000 Time Since New (Hours) Quantityof EngineswithWinstedNon-TumbledBearings .00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00% Distribution of Winsted Non-Tumbled Ball Population vs Cumulative Percentage of Winsted Ball Cracking Cumulative Percentageof Bearing Failures Frequency Cumulative % • The CFM56 engine program has had eight UER＊s for Ball Cracking due to a change in the manufacturing process - Non-Tumbled Balls 每 Detected via MCD inspection and resulted in UER＊s (no IFSD＊s) 每 Ball Cracking is due to Residual Tensile Stress on the surface of the ball • Last Winsted UER in December 2001 CFM56 No. 3 Ball Bearing Reliability Ball Residual Tensile Stress Winsted Non- Tumbled Bearings Cumulative MEFH IFSD (all) UER (Residual Stress) UER (Other Causes) Total CFM56-3 125 1.03 1 4 8 12 CFM56-5A 60 0.49 0 0 0 0 CFM56-5B 221 1.47 2 4 2 6 CFM56-5C 88 1.01 2 0 3 3 CFM56-7B 467 3.32 1 0 2 2 Total 961 7.33 6 8 15 23 Current population of Winsted Non-Tumbled Ball Bearings Fleet Status as of 9-17-02 77% greater than 6000 hours • Ball Cracking caused by High Tensile Residual Stress 每 Process Change at Winsted Ball Mfg Co. 4Q, 1996 每 1018 Bearings Total - ~960 still in revenue service • Corrective Actions Implemented 每 Residual Stress Specification Implemented 12/00 每 Heat Treat and Improved Tumbling Process are now VSE controlled at all vendors • Weibull analysis supports Infant Mortality Failure Mode 每 ~88% of all failures occur in first 6000 hours 每 ~80% are greater than 6000 hours TSN • Ball spalls propagate slowly due to random tracking nature of the ball Normal MCD Inspections aarreeaaddeeqquuaatteettoopprreevveennttIIFFSSDD＊＊ss • CFM56-5B 575-175 was removed for material found on MCD in April＊02 • Investigation showed damage consistent with skidding • CFM56-5B 575-902 showed same type distress • Two CFM56-7B bearings have shown similar distress • One CFM56-5A operator found skidding damage in ＊96 • No root cause determined, no CFM56 finding since Action Plan Team launched to investigate recent failures due to skidding Field Events Skidding Description Background Team Launched to Determine Root Cause • TOPS8D initiated • Field failure teardown investigation • Assess operator flight operational experience • Evaluate bearing condition at overhaul shops • Review rotor thrust and design configuration changes • All bearings experience slip between the balls and inner race. High slip rates occur at/near crossover • Skidding damage occurs when there is metal-to-metal contact when the bearing is experiencing a high slip rate CFM56 No. 3 Ball Bearing Skidding Event Date Eng Mod ESN Customer IFSD UER Brg TSN Engine Delivery Date Last MCDI Oil Type Investigation Findings 17-Dec-01 7B 877-205 Korean X X 3262 Jan-00 424H/377C 2380 Ball Skidding 3-Apr-02 5B 575-175 Alitalia X 1318 May-02 ECD Ball Skidding 1-May-02 7B 889-331 GOL X 3136 May-02 Normal MCD Insp Aeroshell 560 Ball Skidding 11-Jun-02 5B 575-902 Finnair X 916 Jan-02 ECD Ball Skidding • Event Date: 4/3/2002 • Engine Serial Number: 575175 • Engine Delivery Date: 5/1/2001 • AC Tail No: I-BIKF • Pos: 2 • Narrative: ALITALIA HAS RECEIVED TODAY RESULTS FROM THEIR LAB. MATERIAL IDENTIFIED IS M50NIL, FAILURE OF 63 ROLLER BEARING IS NOW SUSPECTED. • ETSN: 1329 • ECSN: 684 • AIRLINE: EUROFLY • Aircraft: A320 • Model Code: 5B • Model Series: B4/P • Thrust: 027000 • Shop Visit Number: 01 CFM56-5B ESN 575-175 Investigation Event Report CFM56-5B ESN 575-175 Investigation Metallurgical Findings Introduction A 3B bearing from a CFM56-5B operated by Alitalia was removed from service after chip indications were observed on the electronic chip detector. The bearing (P/N: 1665M98P02 and S/N: MDAJC205) had accumulated 1318 hours and 679 cycles since new. Figure 1 shows the location of the failure and the bearing in the as-received condition. Conclusions Root cause of the failure of the 3B bearing from Alitalia was believed to be the result of skidding damage. White layer was also found on the aft inner race and on the balls further supporting skidding. Hard particle contamination in the form of aluminum oxide and silicon oxide was also observed along the inside wear path of the cage pockets. Silver and tungsten carbide contaminants were found within a spalled area on the aft inner raceway. The deposited silver can possibly be attributed the silver plating of the cage pockets and the tungsten carbide could possibly arise from the tungsten carbide coated journals on the FWD shaft. The detected hard particle contamination would also tend to worsen the spalling damage. Hardness, case depth, and microstructure for all bearing components conformed to the requirements set by the engineering drawing. CFM56-5B ESN 575-175 Investigation Hardware Condition Photographs showing distress to the outer raceway. A band of distress was observed along the entire circumference of the raceway that was interrupted by spalation patches. No 3 Bearing Outer Race No 3 Bearing Balls/Cage Banding on the Balls Fwd Inner race of bearing showed band of light distress • Event Date: 7/30/2002 • Engine Serial Number: 779129 • AC Tail No: I-BIXO • Pos: 2 • IFSD: E • Narrative: DURING APPROACH ENG 2 ECAM WARNING OIL LOW PRESSURE WAS DISP LAYED. GROUND MAINTENANCE REPORTED PARICULES ON MCD BEARING No.3 SUSPECTED. ENGINE SENT TO LHT FOR INVEST • ETSN: 14374 • ECSN: 9474 • AIRLINE: ALITALIA • Aircraft: A321-100 • Model Code: 5B • Model Series: B2 • Thrust: 031000 CFM56-5B ESN 779-129 Investigation Event Report • No ECD issues on engine prior to the IFSD (no chips on ECD) ECD reported as operational at time of failure/subsequent shop visit • No 3 Bearing on this engine was installed at last shop visit in December, 1999 Alitalia CFM56-5B ESN 779-129 IFSD 7-30-2002 0 20 40 60 80 100 120 140 1 20 39 58 77 96 115 134 153 172 191 210 229 248 267 286 305 324 343 362 381 400 419 438 457 476 495 0 500 1000 1500 2000 2500 3000 3500 4000 4500 N21 N22 OILP1 OILP2 OILT1 OILT2 OILQ1 OILQ2 ALT Shutdown at 260 Oil Pressure Drop of 6-8 PSI ~ 60 Seconds prior to IFSD Oil Temp Increase ~ 30-40 degrees C corresponding with oil P drop Oil Quantity remains constant throughout CFM56-5B ESN 779-129 Investigation (cont) DFDR Data from event Working to understand why oil pressure loss 60 seconds before IFSD CFM56-5B ESN 779-129 Investigation (cont) Hardware condition Forward Oil Nozzle Aft Oil Nozzle No 3 Bearing 每 Balls and Cage Engine sent to LH for repair 每 Confirmed No 3 Bearing Failure • Oil Nozzles damaged from failure (Normal condition) • No 3 Bearing heavily damaged 每 Cage ruptured in multiple locations • Hardware condition noted 每 very little metallurgically to determine root cause • Lubrication Unit returned to vendor for investigation 每 heavily damaged • CFM has requested Scavenge and Supply oil filters for analysis 每 not available CFM56-5B ESN 779-129 Investigation (cont) Hardware condition 每 IGB Assembly Spring Housing shows abnormal oil/heat Forward Oil Nozzle location pattern in area of oil nozzle CFM56-5B ESN 779-129 Investigation (cont) Hardware condition 每 No 3 Brg installed in Spring Housing Outer Race Heavily Damaged Spring Housing • Non-Tumbled Ball Issue has driven reliability in the past 每 Expect this issue to lessen with time - Infant Mortality Mode • Ball Skidding new issue on the CFM56每7B/-5B engine program 每 Engineering Investigation Team Currently Investigating for Root Cause • Two Alitalia No 3 Bearing Failures in 2002 每 Investigation reveals skidding on UER , unknown cause on IFSD 每 Investigation continuing 每 Requesting flight data from customers experiencing skidding distress on their bearings • CFM will keep operators informed of findings as they become available CFM56 No. 3 Ball Bearing Reliability Summary CFM56 No 3 Bearing RReelliiaabbiilliittyyEExxcceelllleenntt

kinran 楷桶衾 2011-6-4 22:58:08

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bocome 楷桶衾 2011-7-31 05:13:56

CFM56-5B No 3 Bearing Review for Alitalia

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CFM56-5B No 3 Bearing Review for Alitalia