LPC Stage 5 Blade failure US Airways / CFMI April 12th, 2001

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This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 1
LPC Stage 5 Blade failure
US Airways / CFMI
April 12th, 2001
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 2
Overview
• ESN 779761 CFMI Investigations Report
• Production Quality Investigation
• Engineering Analysis
• Field Investigations
• Field Program
• General Summary
• Appendix 1
Axial Wave Description
• Appendix 2
On-wing / Shop Inspection Findings
• Appendix 3
CFM56-5A Booster Radial Clearance - Past Experience
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 3
ESN 779761 CFMI Investigations Report
• Contents
– Background
– ESN 779761 - LPC Blade Stage 5 Failures
– Investigation Summary
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 4
Background
• August 30th, 2000. During climb at ~1000 ft., crew reported 3 audible stalls from right engine. No engine
parameter changes reported, no ECAM or fault messages. Throttle retarded to idle, then increased to climb
power with no abnormal response.
• Passengers and crew in cabin reported flashes coming from the engine. A TWA flight departing behind the
A/C reported seeing fire from the engine exhaust area.
• Crew elected to return to field, uneventful landing. Ground visual inspection found NO SIGNS of FOD/bird
ingestion, fan turned freely. .
• After landing, investigation revealed booster/compressor damage. Engine disassembly confirmed 2 LPC
Stage 5 blade failures.
• Additional, investigations performed at CFMI confirmed 2 more cracked blades (same location than crack
initiation on broken blades)
• Engine TSN/CSN: 524/253
• Note 1: FOD has been reported during Flight 4 at AIRBUS/CFMI assembly line
– BSI performed did not revealed any damage at the Stage 5 area, 2 fan blades have to be replaced
• Note 2: No abnormal engine behavior (during revenue service) reported prior to this event
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 5
ESN 779761 – LPC Blade Stage 5 Failures
1 - Suction face
2 - Fatigue rupture initiated on suction face
Failed blade # 1
Origin
Origin
HCF
Beach marks
Note : No reinitiation after each beach marks which cannot be considered as arrest lines
30/11/2000
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 6
ESN 779761 – LPC Blade Stage 5 Failures
Failed blade # 2
1 - Suction face
2 - Fatigue rupture initiated on suction face
Origin
Origin
HCF
Beach marks
Note : No reinitiation after each beach marks which cannot be considered as arrest lines
30/11/2000
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 7
ESN 779761 – LPC Blade Stage 5 Failures
Cracked blade # 3
1 - Suction face
2 - Fatigue rupture initiated on suction face
Origin
Origin
HCF
Beach marks
Note : No reinitiation after each beach marks which cannot be considered as arrest lines
30/11/2000
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 8
• FPI on LPC Stage 5 blades (except the 3 lab. Investigated blades)
– 2 (more) cracked blades, mid chord, suction face, about 3 mm from platform (same location than crack initiation
on 3 broken blades)
• 1 crack : 1 mm
• 1 crack : 20 mm
– Many secondary cracks due to impacts on airfoils
• Visual Inspection on LPC Stage 5 blade
– Heavy wear on every blade tips, mainly from mid chord to TE, and many TE tip curls, due to rubbing on broken
blade "blocked up" on stator abradable. Blade length cannot be established, some blades are bent near
platform from pressure face to suction face, due to the same reason.
– About 20 leading edge tip curls from pressure face to suction face.
– Fretting on many root pressure faces.
ESN 779761 – LPC Blade Stage 5 Failures
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 9
• Stage 5 Booster Stator
– Visual Inspection
• Abradable damaged area located at 06:30
• Rubbing all around the track showing 8 waves (see dimensional inspection on next sheet) more
pronounced TE area
• Secondary damages due to blade ruptures : impacts, rubbing,...
• Abradable Inspection
– Micro analysis on a damage area
• 1st analysis : no anomaly found on samples (no pollution)
ESN 779761 – LPC Blade Stage 5 Failures
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 10
ESN 779761 – LPC Blade Stage 5 Failures
- ABRADABLE DIMENSIONAL INSPECTION
451,000
452,000
453,000
454,000
455,000
456,000
0
5 10 15 20 25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
125
130
135
140
145
150
160155 175170165
180
195190185 205200
210
215
220
225
230
235
240
245
250
255
260
265
270
275
280
285
290
295
300
305
310
315
320
325
330
335340345350355
• STAGE 5 BOOSTER VANE
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 11
ESN 779761 – LPC Blade Stage 5 Failures
1 - Abradable damaged area at 06:30
2 - 8 wave rubbing on abradable
Abradable wave wear pattern
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 12
• Stage 5 Booster Vane
ESN 779761 – LPC Blade Stage 5 Failures
1 - Inner diameter :
abradable black
discoloration in
damaged area
2 - Outer diameter :
thermal discoloration
Cross section in the damaged area
1
2
Melted area
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 13
• Stage 5 Booster Vane
ESN 779761 – LPC Blade Stage 5 Failures
Cross section in the damaged area
1 - Correct structure of METCO 601
2 - Damaged area : no corrosion or
oxidization sign
3 - Melted area on surface
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 14
• Stage 5 Booster Vane
ESN 779761 – LPC Blade Stage 5 Failures
1 - Microscopic examination on an outer ring cross
section, far from the discolored area : correct  structure
2 - Microscopic examination in a discolored area :
no structure transformation
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 15
Investigation Summary
• The two LPC stage 5 blades failures are the consequences of the crack evolutions
initiated in the airfoil convex side few millimeter up from the platform
• Three other blades were also found cracked, with one with the airfoil almost liberated
• The cracks initiation occurred under high stress, their propagation took place under
high cycle fatigue in association with low static and dynamic stress
The blades have been submitted to a flexion/torsion mode, this fact can be generated by
sudden wear contact on TE blade tips
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 16
Production Quality Investigation
• Contents
– Process for F71 Calculation
– Production F71 Clearance Data
– US Airways Production F71 Clearance Data Summary Sheet (Sample Method)
– US Airways Production F71 Clearance Data
– LPC Blade Production Quality Investigation
– US Airways Potentially Affected Fleet
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 17
Process for F71 Calculation
• 1 out of 10 modules are measured
– Sampling method applied since ESN 779-585
• Before 100% assembled booster measurement were performed (3D process with blades secured in
position)
• Analysis of rotor diameter measurement process :
– Procedure
• Stator
– Tri-dimensional measurement performed on 18 points (9 Diameters) on 1 Plane
» Min., Max., Average diameters are considered
• Rotor
– Measurement performed using a low speed balance machine (Rotor in rotating conditions, 1000
RPM)
– Laser measurement performed bladed rotor on 1 Plane (Same plan as Stator)
» The Laser machine is recording all the radius value, then for each blade and its 180° opposite
a Diameter is calculated
» Min., Max., Average diameters are calculated by machine software
• F71 Calculation
– Mini Clearance Diameter Method
» F71 = (Dia. Mini. STATOR - Dia. Maxi. Rotor) / 2
» Comments: Leads to miss potential local over-length, indeed, a over-length blade in
association with its opposite shorter can lead to a F71 within limits
– Forth coming method, Radius method
» F71 = Mini. Radius STATOR - Max. Radius Rotor
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 18
Process for F71 Calculation (Cont’d)
Blade Raduis
452,00
452,10
452,20
452,30
452,40
452,50
452,60
452,70
452,80
452,90
1
2 3 4 5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
32 31 34 33
35
37 36 39 38
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65 66 67 68
Blade Raduis
Maxi. Diameter
Mini. Diameter
ESN 779-761
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 19
Production F71 Clearance Data (Cont’d)
F71 Clearances Distribution Calculated using the Diameter Method
1,46
1,411,41
1,35
1,33
1,36
1,29
1,41
1,36
1,27
1,30
1,34
1,30
1,32
1,28
1,30
1,33
1,44
1,26
1,53
1,28
1,42
1,25
1,18
1,23
1,181,18
1,251,25
1,23
1,28
1,18
1,16
1,18
1,211,22
1,26
1,24
1,10
1,24
1,22
1,19
1,10
1,20
1,30
1,40
1,50
1,60
779-411
779-552
779-583
779-585
779-604
779-622
779-658
779-937
779-668
779-685
779-684
779-693
779-951
779-707
779-717
779-954
779-750
779-744
779-761
779-959
779-769
779-783
779-960
779-797
779-833
779-843
779-876
779-885
779-977
575-109
575-114
779-984
575-129
575-137
575-148
575-153
575-158
575-168
575-181
575-182
575-192
MRB 15W06597-A
Stator Steel Configuration (S/B 72-0351)
MRB issued
Production MRB
Sampling
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 20
Production F71 Clearance Data (Cont’d)
F71 Clearances Distribution Calculated using the Radius Method
1,25
1,27
1,24
1,17
1,33
1,23
1,17
1,19
1,22
1,16
1,23
1,148
1,0991,104
1,269
1,074
1,38
1,171
1,27
1,14
1,04
1,151,15
1,07
1,09
1,12
1,16
1,2
1,081,08
1,13
1,111,12
1,19
1,12
1
1,15
1,09
0,9
1
1,1
1,2
1,3
1,4
1,5
779-411
779-552
779-583
779-585
779-604
779-622
779-658
779-937
779-668
779-685
779-684
779-693
779-951
779-707
779-717
779-954
779-750
779-744
779-761
779-959
779-769
779-783
779-960
779-797
779-833
779-843
779-876
779-885
779-977
575-109
575-114
779-984
575-129
575-137
575-148
575-153
575-158
575-168
575-181
575-182
575-192
Stator Steel Configuration (S/B 72-351)
Production MRB
MRB 15W06597-A
MRB issued
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 21
Production F71 Clearance Data (Cont’d)
• Additional investigation performed on the used production toolings
– Rotors have been measured using the dynamic (balance machine + laser measurement) & static tool (3 D
machine)
• Objective
– Ensure repeatability of measurements with dynamic device
– Ensure proper position of laser on rotor versus stator
– Correlation review between Static and dynamic method
• Findings
– Repeatability of measured confirmed within 0.015 mm (0.000590”)
– The laser “head” is position in the same plane as the one on the stator, in another words the F71
calculation is performed on the same plan
» Since the flow path is conical any deviation may impact the final F71 calculation
– Correlation review between Static and dynamic method has been performed
» It was noticed that the F71 calculation with balance machine/laser is resulting in a
clearance that is tighten versus the 3D process (with blade secure in position) by 0.10 mm
to 0.15 mm (0.00394” to 0.000590”)
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 22
Production F71 Clearance Data
F71 Clearances Distribution Calculated using the Radius Method
1,351,37
1,34
1,27
1,43
1,33
1,271,29
1,32
1,26
1,33
1,248
1,1991,204
1,369
1,174
1,48
1,271
1,37
1,24
1,14
1,251,25
1,171,19
1,22
1,26
1,3
1,181,18
1,231,211,22
1,29
1,22
1,1
1,25
1,19
0,90
1,00
1,10
1,20
1,30
1,40
1,50
1,60
779-411
779-552
779-583
779-585
779-604
779-622
779-658
779-937
779-668
779-685
779-684
779-693
779-951
779-707
779-717
779-954
779-750
779-744
779-761
779-959
779-769
779-783
779-960
779-797
779-833
779-843
779-876
779-885
779-977
575-109
575-114
779-984
575-129
575-137
575-148
575-153
575-158
575-168
575-181
575-182
575-192
100%Booster Dim. Inspection - 3D Process
Stator Steel Configuration (72-351)
Production MRB
F71 Clearance Corrected value
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US Airways Production F71 Clearance Data Summary Sheet (Sample Method)
ESN Mod
Ref. F71 Min. F71 Average F71 max. F71 mini F71 moyen F71 maxi
575-109 AJ1880 1,23 1,35 1,47 1,16 1,35 1,51
575-114 AJ1890 1,28 1,42 1,55 1,2 1,41 1,65
575-129 AJ1910 1,16 1,26 1,38 1,08 1,26 1,47
779-604 AJ1520 1,33 1,49 1,59 1,27 1,48 1,68
779-658 AJ1590 1,29 1,40 1,55 1,17 1,41 1,61
779-693 AJ1640 1,34 1,46 1,60 1,22 1,46 1,64
779-707 AJ1660 1,32 1,49 1,64 1,23 1,52 1,71
779-717 AJ1670 1,28 1,41 1,51 1,15 1,41 1,66
779-761 AJ1719 1,26 1,39 1,51 1,07 1,39 1,76
779-833 AJ1800 1,23 1,33 1,45 1,15 1,33 1,56
779-876 AJ1850 1,18 1,29 1,40 1,07 1,28 1,52
F71 Clearances Distribution Calculated F71 Clearances Distribution Calculated using the Diameter Method using the Radius Method
Steel Stator Configuration (72-0351)
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 24
US Airways Production F71 Clearance Data (3D Process)
ESN TSN CSN Booster
Ref. F71 mini F71 maxi mini maxi
779-389 2521 3471 AJ1289 1,35 1,515 1,32 1,87
779-401 8065 3869 AJ1302 1,555 1,715 1,32 1,87
779-410 8065 3869 AJ1310 1,520 1,690 1,32 1,87
779-411 7136 3403 AJ1311 1,455 1,580 1,32 1,87
779-412 4901 2282 AJ1312 1,485 1,700 1,32 1,87
779-413 8256 3948 AJ1316 1,515 1,660 1,32 1,87
779-414 8223 3861 AJ1314 1,590 1,780 1,32 1,87
779-415 8223 3861 AJ1315 1,370 1,565 1,32 1,87
779-416 8196 3713 AJ1313 1,450 1,640 1,32 1,87
779-430 7840 3445 AJ1330 1,550 1,705 1,32 1,87
779-431 7840 3445 AJ1331 1,515 1,765 1,32 1,87
779-436 3931 1716 AJ1337 1,485 1,695 1,32 1,87
779-437 7711 3452 AJ1338 1,490 1,705 1,32 1,87
779-440 7105 2908 AJ1340 1,615 1,750 1,32 1,87
779-441 7105 2908 AJ1341 1,420 1,620 1,32 1,87
779-454 7414 3306 AJ1352 1,530 1,765 1,32 1,87
779-455 7414 3306 AJ1357 1,520 1,725 1,32 1,87
779-456 7589 3386 AJ1355 1,450 1,620 1,32 1,87
779-457 7589 3386 AJ1356 1,510 1,680 1,32 1,87
779-465 4609 1879 AJ1373 1,555 1,710 1,32 1,87
779-470 7181 3113 AJ1376 1,475 1,615 1,32 1,87
779-498 5231 3036 AJ1397 1,430 1,605 1,32 1,87
779-499 5231 3036 AJ1400 1,550 1,670 1,32 1,87
779-500 6953 3031 AJ1401 1,440 1,575 1,32 1,87
779-501 6953 3031 AJ1403 1,495 1,705 1,32 1,87
Diameter Calculation Method Tolerances
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 25
US Airways Production F71 Clearance Data (3D Process)
ESN TSN CSN Booster
Ref. F71 mini F71 maxi mini maxi
779-508 4075 3677 AJ1411 1,355 1,520 1,32 1,87
779-509 4075 3677 AJ1412 1,420 1,585 1,32 1,87
779-522 2684 2683 AJ1428 1,410 1,615 1,32 1,87
779-523 3605 3898 AJ1425 1,455 1,640 1,32 1,87
779-528 6547 2889 AJ1433 1,430 1,620 1,32 1,87
779-529 6547 2889 AJ1434 1,445 1,565 1,32 1,87
779-536 3475 3855 AJ1443 1,385 1,505 1,32 1,87
779-537 3475 3855 AJ1444 1,395 1,625 1,32 1,87
779-555 6055 2780 AJ1466 1,440 1,630 1,32 1,87
779-556 6055 2780 AJ1468 1,380 1,555 1,32 1,87
779-559 6107 2696 AJ1471 1,440 1,590 1,32 1,87
779-560 6107 2696 AJ1472 1,380 1,595 1,32 1,87
779-561 6106 2709 AJ1474 1,490 1,645 1,32 1,87
779-562 6106 2709 AJ1448 1,380 1,575 1,32 1,87
779-563 5924 2720 AJ1473 1,390 1,605 1,32 1,87
779-564 5924 2720 AJ1476 1,395 1,605 1,32 1,87
779-571 2795 1239 AJ1487 1,430 1,615 1,32 1,87
779-573 3163 3864 AJ1482 1,365 1,640 1,32 1,87
779-574 2491 1341 AJ1488 1,300 1,510 1,32 1,87
779-575 5715 2632 AJ1489 1,505 1,625 1,32 1,87
779-576 5715 2632 AJ1491 1,415 1,510 1,32 1,87
779-577 5837 2623 AJ1490 1,460 1,620 1,32 1,87
779-578 5837 2623 AJ1492 1,350 1,505 1,32 1,87
779-579 2420 1092 AJ1493 1,405 1,580 1,32 1,87
779-580 2790 1251 AJ1494 1,360 1,530 1,32 1,87
779-583 2187 936 AJ1496 1,410 1,575 1,32 1,87
779-584 4983 2175 AJ1499 1,425 1,600 1,32 1,87
Diameter Calculation Method Tolerances
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LPC Blade Production Quality Investigation
• 5 suspected blade batches identified for over-length
End 1999 (Dec.) early 2000 (Feb.)
– Control process reinforced at vendor facilities
• New inspection tool
– 6 points inspection tool instead of
Go no Go gage since May 2000
– Manufacturing purges incriminated batches from
production shelf
• Completed February 2000
• ESN 779761 Failed blades issues from
those suspected batches
• Associated ESN equipped with pre-mentioned
suspected blades identified
– 188 Engines potentially impacted by over-length
blades in the CFM56-5B fleet
– 59 Engines potentially impacted by over-length
blades, in US Airways Fleet
• Additional work is in process to confirm the extant of
the manufacturing lot of engines built with
potentially over length blades
– Target date: April 2001
Before After
Identified Problem
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 27
LPC Hardware Production Quality Investigation
• LPC Booster Blade stage 5
– An in-situ audit was launched at the CFMI Blade manufacturer (April1st, 2001)
• Blades were measured in CFMI Lab
• Same blades were inspected by the blade manufacturer
– No discrepancy noticed between the two inspections
• Stator
– 2 configurations in the fleet Titanium, Steel (Refer to S/B 72-0351)
• Production review for both configuration did not revealed any abnormal manufacturing deviation
• Booster Spool
– MRB have been released on ESN 779-761, for axial position of the stage 5 LPC dovetail slot 0.015 mm /
0.0006”
• Considered as insignificant to the quality issue
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 28
US Airways Potentially Affected Fleet
ESN TSN CSN A/C Position
779647 4577 2122 N725UW 2
779651 2204 3035 N112US 1
779652 2204 3035 N112US 2
779653 4362 2052 N726US 1
779654 4362 2052 N726US 2
779657 3830 1761 N113UW 1
779659 4398 2056 N727UW 1
779660 4398 2056 N727UW 2
779663 3699 1649 N114UW 1
779664 3699 1649 N114UW 2
779665 4161 1889 N728UW 1
779683 3689 1711 N729US 2
779691 3678 1651 N730US 1
779692 3678 1651 N730US 2
779693 2866 1239 N107US 2
779695 3377 1529 N115US 1
779696 3377 1529 N115US 2
779701 3247 1564 N732US 1
779702 3247 1564 N732US 2
779706 3198 1478 N733UW 1
779707 3198 1478 N733UW 2
779710 3206 1449 N736US 1
779711 3206 1449 N736US 2
779716 2601 1184 N116US 1
779717 2601 1184 N116US 2
779730 2677 1139 N117UW 1
779731 2577 1139 N117UW 2
779746 2476 1209 N737US 1
779747 2476 1209 N737US 2
779756 2442 1213 N738US 1
ESN TSN CSN A/C Position
779757 2442 1213 N738US 2
779760 2308 1160 N739US 1
779762 873 1189 N104UW 1
779763 1699 696 N118US 1
779764 1699 696 N118US 2
779767 2332 1111 N740UW 1
779768 2332 1111 N740UW 2
779771 2284 1100 N741UW 1
779772 2195 1047 N743UW 1
779775 1187 541 N123UW 1
779776 N163US 1
779777 2050 881 N119US 1
779778 2050 881 N119US 2
779779 2195 1047 N743UW 2
779780 2284 1100 N741UW 2
779784 1056 531 N729US 1
779785 0 0 SPARE 0
779795 950 462 N762US 2
779808 1542 667 N121UW 2
779831 1104 490 N124US 1
779833 667 630 N753US 1
779834 617 640 N753US 2
779859 1119 534 N760US 1
779863 958 482 N763US 1
779864 958 482 N763US 2
779865 0 0 SPARE 0
779867 0 0 SPARE 0
779871 1099 486 N764US 1
779872 1099 486 N764US 2
779873 235 117
TBD
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Quality investigation Summary
• F71 calculation process with the diameter may leads to miss potential local over-length
• Radius method implemented in production since March 2001
– 3D Process used
– 100% Booster module inspected
• LPC Hardware
– Blade
• Confirmation of the adequacy of the n ew booster blade stage 5 inspection tool in place
– Remaining hardware investigation status did not revealed any timely manner manufacturing
deviation
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Engineering Analysis
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 31
Event / Findings Analysis
• Engineeringanalysis indicates the unusual wave wear pattern of the stator can occurred only if blade
untwists, otherwise, the contact/wear area would be located forward.In such condition the blade would
have been submitted to a flexion mode similar to the one noticed on the CFM56-5A.
• Additional external phenomenon (FOD, Stall,...) needed to initiate stress damages to the blade
• Most probable failure scenario of ESN 779761
– Sudden engagement of LPC blade into the abradable
• Phenomenon origin not consolidated
• Blade untwist suspected based on abradable TE wear evidences
– High tensile stress to blade airfoil that leads to crack initiation
– HCF propagation & airfoil separation
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 32
Engineering Summary
• Additional external phenomenon (FOD, Stall,...) needed to initiate stress damages to the
blade
• BSI performed on US Airways suspect engines did not revealed any damage evidences
( In revenue service & AIRBUS flight line engines)
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 33
Field Investigations
• Contents
– On-wing Inspection Methods
– US Airways BSI On wing & Shop Investigation Status
– Field Investigations Summary
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 34
On-wing Inspection Methods
• Linipot Procedure evaluation
– Testing revealed that we can ’t installed the probe in proper position onto the blade
– It is not possible to check the booster Stage 5 abradable per this inspection tool
• Procedure of abradable Stage 5 on-wing inspection without disassembly elaborated by SnS On-wing
support Team
– Inspection of the booster rotor blades / casing through the borescope port S05.
• This borescope port (S05) located (approximately) at the 3.30 o’clock position at the periphery of the
booster section and almost radially in line with the stage 5 of the booster stator. Through this port
(S05), you can see the trailing edge of the booster stage 5 rotor blades.
– To do this inspection of the booster stage 5 rotor blades / casing :
• 1 Use Fiberscope Set (856A1321 length 2.5 m (8ft 2in.) or equivalent
• 2 Use borescope – Light source set (856A1322P02/P03/P04/P07/P08) or equivalent
– This procedure tested at CFM training school
– Inspection criteria
• Axial wave rub = LPC removal
– More pronounced on T.E. area
• Cracks or burns or heat discoloration = LPC Removal
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 35
US Airways BSI On wing & Shop Investigation Status
• On-Wing
• Shop
SNS USA No rub L/E rub
2 779717 2813/1291 2813/1291 22-mars X CLT X
1 779747 2724/2241 2724/2241 26-mars X PIT X
2 779746 2724/2241 2724/2241 26-mars X PIT X
1 779763 1933/798 1933/798 28-mars X CLT X
2 779764 1933/798 1933/798 28-mars X CLT X
1 779757 2661/1325 2661/1325 29-mars X PIT X
2 779756 2661/1325 2661/1325 29-mars X PIT X
1 575129 42/31 42/31 30-mars X CLT X
2
1 779775 1422/651 1422/651 30-mars X CLT X
2
A/C Pos ESN TSN/CSN TSI/CSI Date Inspector Findings
738
167
123
Location
116
737
118
Location
No rub L/e rub Remarks
779-583 SNS X
779-682 GEAES X
779-411 GEAES X
779-873 GEAES X
779-465 GEAES X
779-604 GEAES X
779-436 GEAES No Stg 5 BSI
779-529 GEAES No Stg 5 BSI
779-527 GEAES X
779-687 GEAES X
779-580 GEAES X
Findings
ESN
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 36
Field Investigations Summary
• BSI performed on US Airways engines did not revealed any damage evidences ( In revenue
service & AIRBUS flight line engines)
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 37
Control Program
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 38
Control Program
• On-wing control program
– Stage 5 blade & Abradable BSI
• Inspection of the booster rotor blades / abradable through the borescope port S05
– General guide lines, will be consolidated in the coming Service Bulletin72-0391 to be issued by April2001
• One time inspection
– 1) First opportunity without interfering with revenue service
• Subsequent inspection recommended to be accomplished when one of the following conditions applies
– (2) Engine had a high-speed stall. Borescope inspection is recommended within 10 cycles or 25
hours (use the limit that is completed first).
– (3) Engine had a FOD such that:
– FOD event met conditions that requested a gaspath inspection (Refer to AMM, Chapter 72-00-00,
Inspection/Check)
– Stage 3, 5 and 9 HPC blades inspection revealed some damage (any type)
» Borescope inspection is recommended within 10 cycles or 25 hours after event
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 39
General summary
• One event since CFM56-5B E.I.S
• Failure scenario established
• Major contributor identified  Over-length LPC Stage 5 blades
– Additional external phenomenon (FOD, Stall,...) needed to initiate stress damages to the blade
• Affected population 188 engines, 59 US Airways
– Manufacturing record review still on-going to close the affected population.
• Completed end of April 2001
– BSI performed on US Airways engines did not revealed any damage evidences
( In revenue service & AIRBUS flight line engines)
• Corrective action in place
– Production
• LPC new manufacturing tools in place
– Recent in situ quality audit confirmed no conformity issue
• Booster production
– 100% inspection of booster assembly using “radius” method
• Fleet recommendation :
– AOW to be released April 2001
– S/B 72-0391 Borescope inspection to be issued
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 40
Appendix 1
Axial Wave Description
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 41
LPC STG5 Distributor
Step
Blade LPC 5
Abradable
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 42
Step
Step
Width increase
Front stator 5
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 43
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 44
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 45
Top of the Wave
Width increase
Width decrease
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 46
Width decrease
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 47
Front stator 5
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 48
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 49
Front LPC Stator 5
Light or no rub
Heavy rub
Step
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 50
Step
Front Stator Stg 5
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 51
Appendix 2
On-wing / Shop Inspection Findings
• Contents
– 779-717 On-wing Inspection results
– 779-717 - Production Data
– ESN 779-756 - On-wing Inspection / ESN 779-757 - On-wing Inspection
– ESN 779-747 & 748 - On-wing Inspection / ESN 779-763 - On-wing Inspection
– ESN 779-764 - On-wing Inspection
– ESN 779-522 - Shop inspection
– ESN 779-604 - Shop inspection
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 52
779-717 On-wing Inspection results
• BSI shows 360° regular abradable rub
• No wave rubbing observed
• Engine released serviceable
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 53
779-717 - Production Data
452,000
452,100
452,200
452,300
452,400
452,500
452,600
452,700
452,800
452,900
1
2 3 4 5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
32 31 34 33
35
37 36 39 38
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65 66 67 68
Blade Radius
Max. Diameter
Min. Diameter
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 54
ESN 779-756 - On-wing Inspection
ESN 779-757 - On-wing Inspection
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 55
ESN 779-747 & 748 - On-wing Inspection
ESN 779-763 - On-wing Inspection
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 56
ESN 779-764 - On-wing Inspection
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 57
ESN 779-522 - Shop inspection
• ESN 522 not listed in list of engine with LPC stage 5 issued suspect batches
• Flex scope could not get into the positions outlined in the Snecma Services procedure.
– Inspectors went through the VBV doors and got some stills in 12 different clock positions.
• No sign of any distress.
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 58
ESN 779-604 - Shop inspection
• No sign of any distress
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 59
Appendix 3
CFM56-5A Booster Radial Clearance - Past Experience
• Content
– Background - Root Cause Investigation
– Corrective Actions - CFM56-5A/5B Comparison
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 60
Background - Root Cause Investigation
• Background
– Numerous cases of stage 4 booster blade damages in service in early 90 ’s
– Type of damages
=> Trailing edge tip corner missing
=> Leading edge airfoil crack
=> Booster blade failure
– Consequence of heavy rub on METCO 601 abradable material
– Cases often associated with particular events such as
=> FOD / birdstrike
=> High speed stall
=> Vibration
• Root Cause Investigation
– Cause identified to be excessive blade penetration into abradable, leading to :
=>Overstress on booster blade airfoil root
=>Various damages and potential failure
Main contributors
=>Too tight clearances
=>Blade over length leading to too tight clearances
=>articular events such as FOD/birdstrike/high speed stall
=>Steel blade locks and counter balance weights leading to evidence of booster spool ovalization
This document and the information contained are CFMI property and shall not be copied nor disclosed to any third party without CFMI prior written authorization 61
Corrective Actions - CFM56-5A/5B Comparison
• Corrective Actions
– Shop level
• Back in 1988
– S/B: 72-038
» To reduce all stages blade length
» Adds radius to blade leading edge tip
» incorporated ESN 731-141 & up
• 1989/90
– S/B: 72-100 / 185 to increase abradable land for stator stages 3 / 4
» S/B 72-100 (Stage 3) Introduced ESN 731-202 & up
» S/B 72-185 (Stage 4) Introduced ESN 731-318 & up
• 1991
– At first booster exposure
» S/B: 72-226 to inspect/rework stage 4 blade length
• 1992
– S/B: 72-315 for stages 2/3/4 titanium blade locks introduction instead of steel (at customer option),
introduced ESN 731-652 & up
– On wing control program
• 1991
– S/B72-152 for on-wing borescope inspection of stage 3 and 4 blades
• CFM56-5A/5B Comparison
– Booster spool design less subjected to ovalization due to presence of aft hub
– CFM56-5B booster spools equipped with titanium blade locks since EIS

979199501

CFM56-7B TRAINING MANUAL ENGINE FAN TRIM BALANCE

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LPC Stage 5 Blade failure US Airways / CFMI April 12th, 2001