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September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 1 HPT Blade - Overview • Blade Configuration • Trailing Edge Root Cracks • Shank Separation • Airfoil Separation • Trailing Edge Separation September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 2 2002M52P05 N5 Full Wrap TBC Improved Film Cooling P05: -7 Baseline (1997) 2002M52P09/P11/P14 N5 P09 Full Wrap TBC P11 1/2 Wrap TBC Platform Cooling P14 same as P11 with Thinned Shank Coating P09/P11: SB 72-115/116 (1999) P14: SB 72-337 (2001) N5 P11 plus optimized T/E cooling Shank improvements M10P01: SB 72-0351R1 (2002) 1957M10P01 CFM56 HPT 3D Aero Blade Configurations September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 3 HPT Blade Root Trail Edge Cracks September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 4 HPT Blade Root Trailing Edge Cracks BACKGROUND • Early blade design have exhibited root trail edge cracks in service - 2002M52P05 HPT blades affected + 373 -7B engines delivered with P05 blades • No IFSD’s • 20 UER’s Reported to Date - HPT blade detailed borescope inspection proven effective September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 5 HPT Blade Root Trailing Edge Cracks 2002M52P05 Area of root trailing edge crack initiation and propagation September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 6 Reduced Borescope Inspection Program Proven to be Very Effective HPT Blade Root Trailing Edge Cracks • Containment program - borescope inspection - Focused inspection required for detection + Training video produced and distributed to all customers + Fleet Highlites articles written to increase awareness + Contact CFMI if assistance required with training • Service Bulletins issued for borescope inspection - -7B S/B 72-326 -- Issued June 2001 + 2002M52P05 blade only - Reduced borescope inspection intervals - every 1000 cycles September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 7 Typical TE Crack Indication HPT Blade Root Trailing Edge Cracks Borescope • On-Wing Maintenance Manual Limits for Root Trailing Edge Cracks - Every 400 cycles if crack is less than 0.120 inch (3,0 mm) - Every 200 cycles if crack is between 0.120 and 0.200 inch (3,0 to 5,1 mm) - 40 cycle over-service extension if crack is between 0.200 and 0.300 inch (5,1 to 7,6 mm) September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 8 HPT Blade Root Trailing Edge Cracks • Corrective action program - 2002M52P09 / P11 blade introduced in 1999 + Factory endurance testing has demonstrated 3X improvement in T/E root airfoil capability over the P05 - 2002M52P05 blade retirement program at next shop visit + -7B S/B 72-115R2 revised June 2001 - Category 4 • Logistic plan in place • Special procedure developed to change blades - ESM 72-00-52, Special Procedure 002 - Shop visit not required in most cases - Replace all 80 blades without removal of HPT disk using pre-ground, balanced blade Kit PN 737L325G03 (SB 72-351R1) - December 2001 Fleet Highlites article introduced procedure September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 9 • Further durability improvements - 1957M10P01 HPT blade - 10,000 accelerated development engine cycles…. no visible cracks. • Production introduction - -7B + (SAC) 888-767, -772, -773, -776, -777, 779, -780 through -793, -796 and up + (SAC) 889-795 and up + (DAC) 876-757 and up • HPT blade kit PN 737L325G03 - Kit contains a set of 80 HPT blades, PN 1957M10P01 that have been pre-ground, balanced and numbered - Released by SB 72-0351R1, June 2002 M10P01 Factory Testing Demonstrating Further Improvement in Trail Edge Crack Capability HPT Blade Root Trailing Edge Cracks September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 10 Enhanced HPT Blade P/N 1957M10P01 Reduced row 1 flow (13 vs. 19 holes) Extend row 8 to platform (added 1 hole) Add 4 holes to root Uniform row 8 spacing Reduced size trailing edge slots (0.040 to 0.033”) Pressure side cooling near the platform Major Features same as P11/P14 • N5 Material • Optimized cooling • Pt-Al base coat • TBC on pressure side Smoothed internal shank cooling passage geometry with same thinned internal coating as P14 blade September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 11 CFM56 3D Aero HPT Blade Shank Separation September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 12 HPT Blade Shank Cracking • CFM56-5B6/2P IFSD - November 2000 - Contained - TSN / CSN = 9027 / 8745 - HPT Blade separated in blade shank + HPT Blade PN 2002M52P04 + One other shank separation due to secondary damage + Other blade airfoils separated due to secondary damage Event Description September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 13 • Only shank separation event to date - Over 3900 engines in -5B/P and -7B fleets - Over 12 million cycles HPT Blade Shank Cracking 3 D A e r o F l e e t H i s t o g r a m 0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 4 0 0 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 In s t a lle d H P T B la d e C y c le s S in c e N e w Number of Engines C F M 5 6 - 5 B /P C F M 5 6 - 7 B Event September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 14 BACKGROUND • HPT blade is a single crystal N5 material, with an aluminide internal coating - Coating reduces oxidation/corrosion - Three coating processes used + All three coating processes within specification + Coating thickness correlates with process • Coating thickness affects LCF initiation - Verified via laboratory specimen testing - Thinner coating better • Cracking initiated at high stress location - Cooling cavity transition HPT Blade Shank Cracking September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 15 Cross Sectional View of Cooling Cavity Local stress riser at transition 0.420 inch (10,7 mm) HPT Blade Shank Cracking September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 16 Metallurgical Investigation • Initiated at mid-cooling passage – Initiation / propagation in Low Cycle Fatigue (LCF) – Transitioned to crystallographic fatigue – Shank geometry common to all 2002M52P04 through P14 blade part numbers Crack Location Cross sectional view of cooling cavity Primary blade Separation Secondary blade separation (Tensile overload) HPT Blade Shank Cracking September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 17 • Ten engines removed to sample high-cycle blades - Five CFM56-5B/P (up to 7599 CSN) - Five CFM56-7B (up to 9050 CSN) - Two of the three coating processes represented + Limited data from second process + Blades from third process too young for meaningful data • Findings - Approximately 5000 blades inspected + Sampling engines plus routine shop visits + Visual, eddy current, and metallurgical - 290 blades have been found with shank cracks + All cracked blades from process that yields thickest coating + All cracks detected using Eddy Current probe & verified by cut up Field Investigation Cracking Not as Severe as Originally Estimated HPT Blade Shank Cracking September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 18 • Interim action taken: - PN 2002M52P14 blade released + CFM56-7B SB 72-0337 • ESN Intro.: 889-505 and up • 888-477, -496 through -497, -503 and up - Thinner internal coating in shank area • New blade introduced, PN 1957M10P01 - Phased production introduction started in 4th quarter 2001 - Same coating process as P14 blade - Redesigned internal casting geometry to reduce stress - Released to field by SB 72-0351R1, June 2002 Blade Design Changes HPT Blade Shank Cracking September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 19 Blade Rework • CFMI has developed a strip process for blade shank coating removal. Steps: - Inspect for internal cracking with Eddy Current probe - Strip process to remove internal coating - External coating replaced by rejuvenation or full/tip repair - Re-identify to new part number + 2002M52P09 will be re-identified as 1957M72P01 + 2002M52P11 will be re-identified as 1957M72P02 • SB 72-0389 issued Sept. 13, 2002 (Cat. 6) HPT Blade Shank Cracking Test Program • Factory engine test cyclic endurance testing on-going - Mix of field returned high cycle blades, redesigned blades, reworked blades - Data to supplement field data - Engine has accumulated 4500 cycles, first inspection no cracks found - Target completion 4Q02 September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 20 Field Recommendations • Current maintenance recommendations - No on-wing inspection possible (internal coating) - At SV, process HPT Blades per SB 72-0389 • Update on field findings and metallurgical evaluation to be provided as data accumulates - Continue to evaluate blades returned from routine shop visits - Continue detailed metallurgical evaluations of blades + Including data from the other coating processes • Establish field recommendations based on field returned blade findings - Coating process - Engine model / rating differences - Data supplemented by factory engine test HPT Blade Shank Cracking September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 21 CFM56-5BP/-7 HPT Blade Airfoil Separation September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 22 Events HPT Blade Airfoil Separations • Five airfoil separation events, two CFM56-5B/P, three CFM56-7B - Time, cycle and thrust ratings vary - All engines were first run Event date Model ESN Rating TSN CSN Part Number May 2000 -7B *875-256 B22 5057 3265 2002M52P05 Nov 2000 -7B 874-163 B24 6401 6164 2002M52P05 Feb 2001 -7B 876-561 B26 769 1006 2002M52P11 Jul 2001 -5B/P *779-384 B3 1567 758 2002M52P05 Jun 2002 -5B/P *779-795 B6 4968 2800 2002M52P11 • Events have similar overall characteristics -5B/P -7B - Airfoils separated just above platform - No evidence of abnormal operation - No evidence of combustor involvement - No source of fatigue stimulus identified - No evidence of manufacturing related cause • 3 of the 5 failures prime blade identified* - two of the prime blades noted with yttrium inclusion at fracture origin - third prime blade sight of origin obliterated by secondary damage September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 23 HPT Blade Airfoil Separation Rupture Tensile overload LCF HCF Potential Root Cause Flowchart Eliminated Probability Potential Separation Mechanisms Scenarios Low High Medium • Pre existing trail edge root cracks • Material pedigree • Coating impact (internal cracks) • Local stress exceeds material capability • DOD/FOD • Loss of cooling flow • Plugging in blade • Plugging in inducer • Loss of retainer sealing • Material pedigree • Pre existing cracks/missing material (frequency shift) • Material pedigree • Coating impact (internal cracks) • Loss of damping • High mean stress • Vibratory stimulus • HPT nozzle area • Combustor profile/pattern • Fuel staging • Fuel nozzle flow • LPT nozzle area • TBV scheduling • Secondary flow circuit HPT Blade Airfoil Separations Telemetry testing to investigate September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 24 • Telemetry test conducted to measure blade vibratory stress levels under various engine operating conditions - Overall blade responses similar to previous blade tests - One blade had higher than expected response on blade tip gage after throttle burst to take-off speed conditions • 2nd build of telemetry engine conducted to validate blade response - 2nd test complete, response on the one blade did not repeat - analysis being conducted to understand Investigation Status HPT Blade Airfoil Separations September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 25 • Investigation Continues - blade/disk tuned blade FEA analysis in process + measure blade frequency variations for first and second builds + use analysis and measured frequencies to determine if the rebuild and selected blade replacement changed response + perform Monte Carlo analysis to predict stress response distribution - Activity to change blade material from full chemistry N5 to N5- low sulfur has begun + similar to -5C, -5B, and -5A + improved producibility + casting face coat less prone to spalling (non-yttrium) - easier to detect by NDT Investigation Status Continued HPT Blade Airfoil Separations Five (5) HPT 3D airfoil separations in over 20 million flight hours and 12 million cycles ?????? September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 26 CFM56-5BP/-7 HPT Blade Trailing Edge Separation September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited Background 6 field events of HPT blades with missing trailing edge material • Missing HPT blade material observed on factory endurance engine 779-193/4a ESN Blade PN PTSN PCSN 779311 2002M52P05 9025 3968 779318 2002M52P05 7942 5002 874494 2002M52P09 9403 3249 875240 2002M52P05 10459 3772 875533 2002M52P09 11275 3417 875152 2002M52P05 18829 5454 2 findings of HPT blades with radial crack indications • PCA ESN 875201, 5 blades, TSN/CSN 12845/4802 • ESN 874222, 1 blade, TSN/CSN 14608/5361 - both found at piece part inspection -5B/P & -7B HPT Blade TE Liberations September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 28 -5B/P & -7B HPT Blade TE Liberations CFM56-5B/P and -7B HPT Blade Age Distribution Currently Installed 0 50 100 150 200 250 300 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 Part Cycles Since New Quantity 2002M52P04 2002M52P05 2002M52P09 2002M52P11 2002M52P14 1957M10P01 Separations range ~ 3K to 5K CSN September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 29 Investigation Status Metallurgical investigation determined that an LCF crack initiated on the inside wall of passage 8 of the airfoil - Crack propagates to liberate blade trailing edge material - Team working to confirm crack initiation is due to a high stress concentration that results from a sharp corner machined into the blade core - Analysis of rib geometry in process to evaluate potential populations and potential geometry improvements - Statistical analysis suggest a batch issue (many parts past cyclic life of failed parts) Current Field Recommendation • No change to current maintenance recommendations - All occurrences found during routine borescope inspection, only minor down stream damage reported - No reports of engine vibration increases • Working to establish AMM limit for continued operation - one engine currently under reduced BSI via. CDR - contact CFM to place engine under reduced BSI via. CDR for continued operation • X-ray inspection to be added to Repair Document - x-ray process being developed to detect cracks at routine repair -5B/P & -7B HPT Blade TE Liberations September 2002 WTT face to face CFM / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 30 • Root Trail Edge Cracking - Limited to P04/P05 initial production blades; 373 engines - Field plan in place for in-service inspection and replacement at shop visit - Improved designs available • Shank Cracking - One event in over 12 million cycles in CFM56 3D aero HPT blade fleet - Root cause understood; cracking due to material property degradation from coating - Factory engine testing, field blade retrieval on-going to characterize coating populations and life capabilities - Service Bulletin issued for internal shank cavity strip at next blade repair • Airfoil Separations - Five events in -5B/P and -7 fleets - Telemetry testing; analysis underway to understand results - No field action required at this time • Trailing Edge Separations - Root cause being confirmed - CFMI working to identify affected blade part number population - CFMI will continue to update at WTT and Focus Team calls - Reduced BSI interval via. CDR being used to substantiate a AMM limit Summary HPT Blade |
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