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“3 Rolls-Royce

(Engine Investigation) Accident investigation

Rolls-Royce Allison Model 250-C30H Engine CAE 900074

Helicopters by Oz Baggs, Wyoming

w-w. Se+F Warren W. Seitzinger Accident Investigator

Accident date: 10 October 2000 Report date: 22 May 2001

1 uaa3 Rolls-Royce

(Engine Investigation) Accident investigation

Rolls-Royce Allison Model 250-C30H Engine CAE 900074

Helicopters by Oz Baggs, Wyoming

w-w. Sedpy3& Warren W. Seitzinger Accident Investigator

Accident date: 10 October 2000 Report date: 22 May 2001

TABLE OF CONTENTS

1. SYNOPSIS.

2. FACTUAL INFORMATION.

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.1 1 2.12 2.13

History of Flight Personnel Infomation Injuries to Persons Aircraft Information Meteorological Conditions Aids to Navigation Communications Accident Site Information Flight Recorder Wreckage and Impact Information Engine Examination Engine Maintenance and Records Additional Information

3. FINDINGS.

4. APPENDICES.

4.1 Photographs 4.2 Metallurgical Report 4.3 Engine Technical Data 4.4 Engine Maintenance Records 4.5 Investigation Participants

250-C30H, SIN CAE 900074, Helicopters by Oz, Baggs, WY, 10 October 2000

1. SYNOPSIS

On 10 October 2000, at approximately 09 15 Mountain Daylight Time (MDT) a MD 369FF helicopter, with an Allison 250-C30 engine, registration N8263 8, operated by Western Geophysical, was involved in a forced landing accident near Baggs, WY. The forced landing resulted from an engine failure, which occurred while the aircraft was hovering at approximately 130 feet AGL (above-ground-level). The helicopter incurred substantial damage and the pilot, only sole onboard, sustained serious back injuries. The National Transportation Safety Board (NTSB) requested manufacturer's assistance in the investigation, Boeing helicopters and Rolls-Royce Corporation complied. The investigation was conducted on 17 October 2000, at Beegles Aircraft Services, Inc., Greeley CO., the recovery site of the aircraft. The engine was shipped to Rolls-Royce Corporation (RRC), Indianapolis, IN, for further disassembly and examination, which was conducted 1-2 November 2000.

2. FACTUAL INFORMATION

2.1 Historv of Flight. Per the pilot's statement, on 10 October 2000, while flying N82638. he had been positioning equipment to various locations, in hilly terrain. in support of seismographic operations near Baggs, WY. The equipment was described as a carousel with seismographic equipment attached to a 75-foot cable, which was hung below the belly of the aircraft. After approximately 1.5 hours into the mission, the pilot had arrived at an equipment drop-off site wherein he brought the aircraft to an approximate 130 feet hover in preparation to position the load for drop-off. While at the out-of-ground-effect-hover. the pilot reported that he heard a "pop" or "bang" and the engine quit. The pilot immediately attempted a vertical autorotation while descending an approximate 30 degrees down slope, wherein the tail skid made the first terrain contact before the aircraft came to rest upright. The force of the landing resulted in total collapse of the skid gear assembly and extensive upward crushing of the lower belly. Nearby witnesses responded immediately and, along with rescue workers, extricated the pilot from the wreckage with a "Jaws of Life". The pilot sustained serious back injuries and was transported to a hospital by an air ambulance.

2.2 Personnel Information. The pilot, 47 year old Robert P. Nolan, West Jordan, UT, possessed a Commercial Pilot Certificate (2504204); with ratings in airplane and rotorcraft and had a current Class I1 medical Certificate. He was rated in several different helicopters. He had accumulated approximately 13,200 hours flight time. Approximately 12,500 hours were in rotorcraft and approximately 500 hours in the MD 530FF.

2.3 Injuries to Persons. The pilot sustained back injuries.

2.4 Aircraft Information (times are approximate, derived from Hobbs Meter recordings). The aircraft had undergone a major rebuild at 2657.1 (AFTT) following a hard landing, which occuned while the aircraft was registered in Colombia, S.A. The aircraft rebuild was completed in August 2000 and the current owner took possession of the aircraft on 28 August 2000.

Model Serial Number Registration Number Airframe Total Time Last Inspection

MDHI 369FF 0056FF N82638 2750.0 2657.1


Engine Model Rating: Serial Number Engine Total Hours

Allison 250-C30 650 Shaft Horsepower CAE 900074 2750.0

2.5 Meteoroloeical Conditions. The weather was reported as VMC (visual meteorological conditions).

2.6 Aids to Navigation. NIA

2.7 Communications. N/A

2.8 Accident Site Information. Reported as hilly, desert terrain with Yucca plants. approximately 7000 feet MSL.

2.9 Flight Recorder. Flight data recorders were not installed.

2.10 Wreckage and Impact Information. The aircraft was first seen at the recovery site loaded onto a flat bed trailer. Damage to the airframe indicated that the aircraft had experienced a hard, vertical landing, which resulted in approximately 12 inches upward crushing of the belly, the remainder of the fuselage was intact. The skid tube assemblies were intact, however, the fore and aft cross tubes were flattened. The tail boom was intact with main rotor blade impact scarring on the upper surface. Approximately 8 inches of the lower vertical fin was covered with mud. evidence that it had penetrated soft soil during touchdown; the tail skid was missing. The main rotor blades were intact and exhibited low RPM impact damage signatures; two blades approximately 12 to 18 inches outboard of the grip, were bent over approximately 30 degrees. The rotor head appeared undamaged. The tail rotor drive shaft experienced a torque shear (sudden stoppage) approximately 18 inches aft of the forward hanger bearing. The tail rotor assembly was intact and attached to the tail boom; both blades exhibited minor sideward bending.

2.1 1 Engine Examination. The engine was found intact on the airframe. The upper engine mounts were undamaged; the lower mounts were bent slightly downward. Additionally the following was noted and I or accomplished:

0

All fluid lines were intact and all fittings were tight. All engine controls, PTG, FCU, and FP appeared undamaged. The outer combustion case (OCC) had impact dents on the rear face and lower surface. The gas producer (GP) support had evidence of bulging just aft of the split line between the GP and the power turbine (PT). Eight split line bolts were missing (failed). There was evidence of an external, localized fire below the turbine.

The engine was removed from the airframe and the following was noted:

The compressor impeller would rotate, but not freely; N2 would not rotate. Both chip detectors were examined, both appeared normal with no particulate present. An oil sample was taken from the engine oil tank and retained for analysis at RRC, Indianapolis.


0 Alignment of the shafting - Alignment of shafting was verified by marks placed on shafting during assembly. The Compressor to Turbine Coupling was a tight fit on the SAG and a loose fit on the turbine adapter.

The turbine section exhibited evidence of the presence of lubrication, throughout, despite dryness in heat distressed areas. All bearings in the turbine were intact and rotated in their races.

Body-bound bolts were installed. 0

NOTE:

During the disassembly, two parts were identified as FAA PMA parts (documented in engine logbook). -

0

0

Spur Adapter Gearshaft - P/N, E 23008090-B, S/N CI 10-22 I . Turbine Tie Bolt - P/N, E 23008030, S/N HSI-109.

It was decided to send the following parts to the Materials and Processes Laboratory, RRC. Indianapolis, for analysis. Results of the metallurgical investigation are contained in Appendix 4.2.

SAG Turbine Tie Bolt Compressor to Turbine Coupling

0 1'' Stage Nozzle 0 1st Stage wheel

2nd Stage M e e l No. 8 bearing retaining nut

2.12 Engine Maintenance and Records. A review of engine maintenance records revealed that required inspections and applicable service directives had been complied. The turbine had undergone an overhaul at 2657.1 hours, ETT, on 5-31-2000, by Dallas Airmotive, Inc. (QT2R121L), Milleville, NJ. During the overhaul, a 4* stage wheel, with 0.00 TT was replaced. The 3'd stage wheel had 1436.0 hours, TT, and the installed 1'' and 2"d stage wheels had 370.0 hours, TT. Also, the fuel control unit, power turbine governor, and fuel nozzle were installed with 0.0 TSOH. The engine had accumulated 93.0 hours since the overhaul and up to the time of the accident.

Records indicated that two FAA, PMA parts were installed at the past recent overhaul:

0

0

Turbine Tie Bolt, PN E23008030, S/N HIS-109 Spur Adapter Gearshaft, P/N E23008090-B, S/N CI 10-22 1,

Both were examined and measured to Rolls-Royce engineering print specifications, no anomalies were noted of either part.

. -


The engine was prepared for shipment and installed in an engine container for shipment to RRC, Indianapolis for disassembly and inspection.

Engine - disassembly and inspection, Rolls-Rovce Corporation. Indianapolis. IN, 1-2 November 2000.

The engine was removed from the container and inspected with no shipping discrepancies noted. The following was accomplished / noted during the disassembly:

Controls (PTG, FCU, and FP) were removed - all were intact. undamaged. Air discharge tubes, OCC, and combustion liner removed - all were intact and no anomalies were noted of the interior surfaces. The gas producer support was found bulged and ruptured at the 6 O'clock position exposing a ruptured energy absorbing ring and fragments of failed intemal parts.

The compressor assembly was removed and followed by removal of the turbine. The power turbine (PT) and gas producer (GP) modules were further separated. During the process, the following was noted:

Compressor - once removed, rotated freely and smoothly and the spur adapter gear shaft (SAG) was intact. 1'' stage nozzle shield - intact, however, all struts were distorted and broken at the outer ring. No. 8 bearing sump cover - center dimpled outward, evidence of contact with the turbine tie bolt. 1'' stage nozzle - intact, distorted, the trailing edges of many vanes were eroded or broken away, FOD damage. The GP was distorted and 12 split-line bolts were missing from the left side mating holes; some were found on the lower fire shield along with fragments from failed intemal parts, which had exited through the rupture in the GP. The compressor to turbine coupling was failed at the turbine end. Approximately 60 % of the splines were broken away up to 3/4 inch; fragments were retrieved. The compressor end of the coupling was intact and the splines appeared undamaged. Turbine shaft to pinion gear coupling - intact, oily, no visible damage. The 1" stage wheel was destroyed, fractured into numerous pieces from the bore outward. The energy absorbing ring was destroyed; it was expanded outward, it's entire circumference, and lodged in the interior of the GP support. Turbine tie bolt was failed, found in three pieces. No's. 5,6,7, and 8 bearings were intact and rotated; the #8 bearing retaining nut exhibited two cracks, longitudinally through the threads, approximately 180 degrees apart; the retaining nut was removed in two pieces. 2nd stage nozzle - FOD impact damage, suction side; some vane tips broken away. 2nd stage wheel - FOD damage all blades (broken tips); curvic coupling splines exhibited rub damage. 3'd stage nozzle - FOD impact damage at vane tips. 3'd stage wheel - FOD impact at blade tips, suction side. PT - evidence of FOD ingestion, the assembly was not disassembled. Turbine Spline Adapter - very loose fit on the 2nd stage wheel; the splines were intact but exhibited rotational rub damage.

250-C30H, SIN CAE 900074, Helicopters by 0 2 , Baggs, WY, 10 October 2000

Component Engine Gearbox

Part Number Serial Number TSO Total Time 23009300 CAE 900074 NEW 2750.0

NEW 2750.0 23008586 97574

2.13 Additional Information. The owner of the aircraft provided a history of discrepancies with respect to the engine, which were noted after acceptance of the aircraft. NOTE: The following were not noted in the daily operational logs.

8-28-00 - Acceptance flight, ferried to Utah, no discrepancies noted.

0 8-3 1-00 - Compressor stalls / no loss of power, no follow-up action except consults with engine technicians.

0 9-12-00 - Drop in oil pressure from 1 15 to 105 psi, consulted Dallas Airmotive and was told to change oil several times. Oil was changed and oil pressure was adjusted to 1 15 psi.

9-1 9-00 - Slight compressor stalls / no loss of power.

9-26 to 9-29-00 - Conducting Seismic support, compressor stalls / no power loss.

0 10-2-00 - Drop in oil pressure, changed oil.

0 10-1 0-00 - Flight of 1.5 hours, engine failure.

3. FINDINGS.

3.1. Failure of the Turbine to Compressor Coupling resulted from fatigue originating in the ID spline roots adjacent to the aft end chamfer.

3.2. Measurements of wear depths along the spline axis, indicated tapered or off axis wear, strongly suggesting misalignment of the Turbine to Compressor Coupling and Turbine Splined Adapter.

3.3. Wear patterns on the Turbine to Compressor Coupling Splines indicated wear depths ranging from 0.001 3 to 0.0038 inch, further indicating accelerated wear resulting from misalignment.

3.4. Failure of the First Stage Turbine Wheel was due to overspeed burst resulting from and secondary to the failure of the aft end of the Turbine to Compressor Coupling.

0


3.5. The material chemistry, microstructure, hardness and case depths of the Turbine to Compressor Coupling satisfied the engineering drawing requirements.

Stack Alignment

GEARBOX

12 2 4 6 8

10

Shims Actual #

0 0 .006 .006 3 .002 0

0 .002 1 .002 .002 1 .004 .004 2

12 2

I EXHAUST

.008 .008 4

.006 .006 3

COMPRESSOR

.006 .006 10 .006 .006

250-C30S Failure Investipation _-

Gearbox Measurements - Turbine Mounting Face

- Letters represent the location of each mounting pad - Each pad was measured from a leveled reference plane. All measurements are referenced to that plane. Concentricity measurements were made using the reference plane as the primary datum and the cage ID as the secondary datum.

-

I2:OO Cage ID

D

I 1 View Looking Into Mounting Pad

Posit ion Pad Height A -.0006 B -.oo I O C -.0004 D -.oo 13 E -.0004 F -.0009

Max variation = -.OO 13-.(-,0004) = -.0009"

Concentricitv (Gear ID with respect to Cage ID)

.0009

.oo I O 1 Concentricity = .OO 13" @ 1 3€i0 CW From 12:OO Position

Gearbox Measurements - Compressor Mountin. Face

- Numbers represent the location of each mounting pad - Each pad was measured from a leveled reference plane. All measurements are referenced to that plane. Concentricity measurements were made using the reference plane as the primary datum and the bushing ID as the secondary datum.

-

I2 :OO Bushing ID

Position 1

3 4 5 6

7 -

4

View Looking Into Mounting Pad

Pad Height -.0007 ,001 1

-.oo I2 .ooos

-.0003 -.0002

Max variation = -.0012-.OOOS = -.0020"

Concentricitv (Gear ID with respect to Cage ID)

,0007 r .0074

Concentricity = ,0025'' @ 106" CW From 12:OO Position

Turbine Measurements - Gearbox Interface

- Roman Numerals represent the location of each mounting pad - Each pad was measured from a leveled reference plane. All measurements are referenced to that Dlane. I - -

- Concentricity measurements were made using the reference plane as the primary datum and tlle pilot OD as the secondary datum.

P;int nn

IV

View Looking Into Mounting Pad

Position Pad Heieht Concentricitv (Gear ID with respect to Pilot OD) I -.0062 11 I l l IV

,0040 .OO 19

-.0057 V ,0030 VI ,003 1

.0007

.0001 7 I v

Concentricity = .0007" Cii, 262" C W From 12:OO Position Max variation = -.0040-.(-,0062) = -.O 102"

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Thm IyhnIuI dab and Ihc mnfonnatlon mnbodoed h e m n 1s the prop- of and

METALLURGICAL . _

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_ . 46206-0420 USA

INVESTIGATION REPORT PAGE PAGES REPORT NO.

00FA8-224 1 OF 35

c - -

METALLURGICAL INVESTIGATION OF TURBINE TO COMPRESSOR COUPLING, P/N 23032345, S/N AE58721, REMOVED

HELICOPTERS BY OZ.

'

FROM MODEL 250-C30H ENGINE S / N 900074, OPERATED BY

REFERENCE:

! PREPARED

J. Allsman

APPROVED

Nicholas. E. Cherolis

DATE

--

RedTop NI-2000- I 80

Part Turbine to Comuressor CouDhg

IDENTIFICATION

P/N S/N i 23032345 AE58721 ' I

PART NAME: PART NUMBER: PART S/N: MATERIAL: TOTAL ENGINE TIME: TURBINE TOTAL TIME: 1'' & 2" STAGE TURBINE WHEELS: TIME SINCE LAST OVERHAUL: ENGINE MODEL: ENGINE S/N: USER:

Spur Adapter Gearshaft 1" Stage Turbine Wheel 2& Stage Turbine Wheel

Turbine to Compressor Coupling 23032345 AE5872 1 AMs 6470 (Nitralloy/l35 Mod) 2750 hr. 2700 hr. 300 hr.

93 hr. 250-C30H CAE 900074 Hekopters by OZ

E23008090-B I CI10-22 1 23053299 X139686

NIA

FOREWORD

I 1 " Stage Turbine Nozzle I 230085 10-B

An MD369FF aircraft, powered by model 250-C30H engine S/N CAE900074, while in a 100 foot hover, sustained an in-flight power loss. Initial examination revealed a failure of the Turbine to Compressor Coupling, resulting in an overspeed burst of the First Stage Turbine Wheel. Selected turbine hardware was returned to Rolls-Royce Corporation and submitted to the Materials and Processes Laboratory for metallurgical investigation. The returned hardware is listed in Table I.

DDl689 17 I

I Turbine Tie Bolt I E23008030 I HA1-109FAA-PMA ~

I Turbine SDlined AdaDter I 6898837-H I 79666 I

OF AS-224 PAGE 2 OF 35

CONCLUSIONS

1. Failure of the Turbine to Compressor Coupling resulted from fatigue originating in the ID spline roots adjacent ., to the aft end chamfer.

2. Measurements of wear depths along the-spline axis indicated tapered or off axis wear strongly suggesting misalignment of the Turbine to Compressor Coupling and Turbine Splined Adapter.

I

3. Wear patterns on the Turbine to Compressor Coupling Splines indicated wear depths ranging from 0.0013 to 0.0038 inch. -- further indicating accelerated wear resulting from misalignment.

4. Failure of the First Stage Turbine Wheel was due to overspeed burst resulting from and secondary to the failure of the aft end of the Turbine to Compressor Coupling.

5. The material chemistry, microstructure, hardness and case depths of the Turbine to Compressor Coupling satisfied the engineering drawing requirements.

RESULTS

Turbine to Compressor Coupling P/N 23032345, S/N A3358721

Visual Examination

Figure 1 shows a schematic view of the Power Turbine Support detail for reference. Damage in the form of axial separation occurred in the splines at the aft end of the Turbine to Compressor Coupling. Figure 2 shows the condition of the Turbine to Compressor Couplin: in the as received condition. The primary fractures occurred along several of the aft end spline roots. The splines were numbered arbitrarily from No.1 through No.27 with Nos.1-11 still attached to the Turbine to Compressor Coupling.

Figure 3 shows the Turbine to Compressor Coupling splines in the approximate relationship with the Turbine Splined Adapter and the Turbine Tiebolt Nut. The components in the photo were assembled after some initial metallurgical sections were made.

Figure 4 shows a close up view of the splines after reassembly. Spline Nos.12 & 16 were missing. Most axial fractures observed along the spline roots were consistent with fatigue-type crack mechanisms. The jagged fracture at the spline root location on either side of spline No.14 was indicative of tensile overload. The flattened appearance of Nos.13, 14 and 15 sugges’t that this segment was crushed at some time after separating from the Turbine to Compressor Coupling. Several coarse cracks were initiated withm the spline roots during attempts to open cracks for inspection. The cracks between Nos.7 and 8 are typical of the lab-induced cracks.

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00FA8-224

9

PAGE 3 OF 35

shallow N 0.16, light & 0.53

Figure 5 is a close up of spline Nos. 1 - 1 1. The arrow points to smeared metal which was confirmed chemically to match the Turbine Splined Adapter base metal. Locations ‘a’ and ‘b’ refer to the widths of the wimess marks due to the Turbine Tiebolt Nut and Turbine Splined Adapter splines. respectively. These wid*$ were measured for each spline. For comparison purposes the lene@ of the Splined Adapter splines was listed as 0.480 hch on the engineering drawing. The measured distance along the flat portion of the splines-on the Turbine Tiebolt Nut varied between 0.13 - 0.15 inch. The actual spline impression measurements from the Turbine to Compressor Coupling are tabulated in Table II.

shallow 1 10 N 0.18. light 0.48 11 N 0.17. light 0.47 12 Y 0.25 N/A. smashed Spline smashed

0.22. tapered AI.45. severe , Spline smashed 13 Y

14 Y 0.22. tapered >0.45. severe Sipficant hear step on spline at chamfer. I

I

wear

wear spline qmached

-- Table II:

1 1 5 l y >0.22. 1 >0.45. severe 1 Sigmficant wear step on splme at chanter. !

16 Y appreciable wear 0.20. &/A

1 I splinesmashed 1 Spline smashed. missing piece I

fietting fretting step on spline at chamfer 23 Y, 19-23 >0.23. fretting >0.50. severe

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Severe fretting on spline face, Significant wear

00FA8-224 PAGE 4 OF 35

Table ZZ indicates that the Turbine to CompressorCoupling did not have any multiple witness marks on the splines whch would occur if the Turbine to Compressor Coupling shifted during operation. The second column documents whether the spline was still attached to the Turbine to Compressor Coupling or was found detached during disassembly. Hyphens between numbers indicate that the splines were found as a group. The liberated splines as a group showed the most severe wear along the loaded surfaces.

SEM Examination

Figures 6 and 7 are SEM images which provide an indication of the uneven damage observed on the splines. The splines shown in Figure 7 show considerable fretting wear. Figures 8 through 10 provide representative spline damage from the lightest (Figure 8) to heavier damage (Figure 10).

The axial fracture surfaces of the Turbine to Compressor Coupling splines were badly smeared. Evidence of fracture origin or crack growth direction was indeterminate from these pieces. A lab- opened axial crack was used for evaluation. Figure 11 shows an SEM image of a lab-opened axial spline crack. The crack initiated along the spline root. The right-hand photo shows a close-up of the fracture surface. The appearance of the fracture through the nitrided case is slightly different from the base metal. The dashed box indicates an enlarged region shown in the top photo of Figure 12. This image shows fracture characteristics indicative of fatigue progression.

Figure 13 shows a transverse view of the root section between spline N o d 8 and 19. Fretting occurred along the loaded surface of the spline in contact with the Turbine Splined Adapter. The extent of spline wear is indicated by the dashed line.

Metallographic Examination

Spline Nos.18 and 24-27 were polished at 0.10 inch increments from the aft end chamfer with spline wear measurements made at each depth (see figures 7&10 for orientation). Measurements indicated that the wear depth increased from the chamfered end. The tapering of the wear depth. whch was similar for both sets of splines, strongly indicates that the Turbine to Compressor Coupling was misahgned with the Turbine Splined Adapter. A graph of the results are shown below in Figure 14.

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00FA8-224 PAGE 5 OF 35

Figure 15 shows a cross section with cracks at the base of the spline. The predominantly linear crack path suggests fatigue type crack growth. The etched photo reveals a nitrided surface structure. Figure 16 shows the microstructure at the case (top photo) and core (bottom photo) which

consisted of a tempered martensitic structure with a nitrided case.

The Turbine to Compressor Coupling mount w& repolished and etched with Marbles etchant to evaluate the case thickness. The case depth measured 0.012 inch as required by the engineering drawing (0.01 1 - 0.015 inch).

_ .

- .

Chemistry

Semi-quantitative X-ray Energy Disper_sive Analysis (XEDA) determined that the Turbine to Compressor Coupling was a type AMs 6470 (Nitralloy/l35 Mod) material as required by the engineering drawing. Smeared material on the crowns of several splines was determined to be a type EMS 64500 material which conforms to the composition of the Turbine Splined Adapter.

The Turbine to Compressor case hardness averaged 91.5 HR15N (91.4, 91.4, 91 .8) which satisfied the engineering requirement of 90 HR15N minimum. The core hardness averaged 27.7 HRC (27, 28,28) which satisfied the en,oineering requirement of HRC 26 - 32.

Turbine Splined Adapter P/N 6898837H, SIN 79666

Visual Examination

Figure 17 shows the Turbine Splined Adapter in the as received condition. The extemal splines. which were in contact with the Turbine to Compressor Coupling, were damaged. The tips of each spline were smeared.

SEM Examination

Figitre 18 is an SEM image of various locations on a typical spline from the Turbine Splined Adapter. The middle image shows deposited metal smeared between the spline teeth. The smeared material within the splines was identified as EMS 64500. No cracks were observed.

Metallographic Examination

Figure 19 shows the nitrided case structure of the spline with a tempered martensitic core.structure. The microstructure is appropriate for the heat treatment specified in the engineering drawing. Note that the tips of the splines have been completely worn. Figure 20 shows an enlarged image of the microstructure at the case and at the core respectively. The core consists of very fine tempered

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00FA8-224 PAGE 6 OF 35

martensite. The thickness of the nitrided case at the base of the spline measured 0.010 inch thick which satisfied the engineering requirement of 0.010 - 0.019 inch thick. -

Chemistry _ . I

Semi-quantitative X-ray E n e r a Dispersive 'Analysis (XEDA) determined that the Turbine Splined Adapter was a type EMS 64500 material which conforms to the requirements of the engineering drawing.

Direct measurement of the case hardness'was not 'possible due to the smeared condition of the spline teeth. The tips of each spline was sheared off. The average hardness in the core was 30.3 HRC (30. 3 1,30) which satisfied the engineering requirement of HRC 30 minimum.

Spur Adapter Gearshaft, Turbine Tie Bolt (P/N E230080!WB, SXV CIlO-221) (P/N E23008030, S/N HA1-109FAA-PMA)

Visual Examination

Figure 21 shows the Spur Adapter Gearshaft in the as received condition. The part number on the surface indicated that this part was not supplied by Rolls-Royce. It appeared to be in relatively new condition with only minor wear to the splines. Normal wear pattems were seen on the gear teeth as shown in the lower right photo. Figure 22 shows a close up of the O-rings from the Aft end of the Spur Adapter Gearshaft. The O-rings were identified as forward and aft respectively. The forward O-ring contained a tear shown in the right photo. The aft O-ring showed damage consistent with contact made from the splines on the forward end of the Turbine to ComDressor Coupling. A tear is shown in the bottom right photo.

Figtire 23 shows the as received condition of the Turbine Tie Bolt. The part number on the surface indicated that this part was not supplied by Rolls-Royce (E23008030). The fracture was due to shearing and was considered a secondary failure. The bottom photo documents the condition of the Turbine Tiebolt Nut splines.

1'' and 2"d Stage Turbine Wheel, 1" Stage Nozzle

Visual Examination

Figure 24 shows the 1'' Stage Turbine Wheel in the as received condition. The fracture of the wheel is characteristic of an overspeed burst. The overspeed occurred when the Turbine to Compressor

PROPRIETARY RIGHTS LEGEND permmuon at ROll4oyce Corpomtaon. be diuloud m whole or in pan to thord patiwa This I w n d shall be enc1ud.d on m y mpmdunlon of tho. dah ~n whole or m p.n Copyright 20oo. Rol ldoycc Corporation (Unpublished)

This technical dah and the mlonn.tion mnbodwd h w " I. the pmpaq ot and pmpnehy to RollcRoyce UIi.on. and shall not. wdhoul pnor wmen

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00FAS-224 PAGE 7 OF 35

Coupling filed. Additional debris found in the engine case is shown in the lower photo. Figure 25 shows the microstructure from the rim section of the 1" Stage Turbine Wheel. The microstructure at this location appeared normal.

Figure 26 shows the 2"d Stage Turbine Wheel. Damage to this wheel appeared to be impact damage from the 1'' Stage Turbine'Wheel. A crossgectio; of an airfoil revealed a normal microstructure. No additional work was done.

Figure 27 shows the 1'' Stage Turbine Nozzle in the as received condition. Severe impact damage occurred due to the 1'' Stage Turbine Wheel burst. Microstructural evaluation of a vane indicated that the microstructure was normal. No further evaluation was performed.

- - _ - .

PROPRIETARY RIGHTS LEGEND permmuon of RoIIcRoyca Corpontlon. be d iu loud in whole M In prl to third p.ni .~ This l e n d &all b. tnc1ud.d on any nproduciion of this data in whol. or in pan Copyright 2033 - RollcRoyce Corpontlon (Unpublmhcd)

This t u h n m l data and th. inlommlion embodl.d h u m 8 - tho pmprty of and pmpn.tay to Rolh-Royce Nl~.on and .hall not. wdhovt pror wmon

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00FA8-224 PAGE 8 OF 35

Figure 1. Sketch showing Power Turbine Support details for reference purposes.

PROPRIETARY RIGHTS LEGEND Tho. k h n l u l dah and the miormatoon unbodied hemin IS the property of and pmpneiay io Rolldoysa *Il~.on. and .hall no( wllhoYt pnot w m m prmisuon of Rolldoyce Corponlion, be diuloud in wholo or In P.R Io third p.Rioa This I-nd ahdl be includd on any mpmduaoon of lhosdah I" whole or in pi Copynghl2ooo. RollcRoyce Corporalton (Unpublmhed)

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00FA8-224 PAGE 9 OF 35

FWD AFT

M a p . 0.6X

Fi I1

No. 1

4

Ma@. 1.4X Light scoring on surface

M a g . 1.4X

? 2. Top photo shows the as received condition of th Turbine to Con: ressor Coupling. Bottom photo shows close up of the fragments and surface distress on the O.D. surface of the Turbine to Compressor Coupling considered the result of the failure sequence.

PROPRIETARY RIGHTS LEGEND pcmivron of R o l l d o y c c Corpnl ion. be disclosed ~n whole or in pan lo third partier This lrgcnd .hall b. mchded on any nproduct~on 01 lhm d.1. I" whole or m part Copynghl ?am - Rol ldoyce Corporation (Unpublmhed)

Th18 1echnicaI d.1. and lhe tnlormation embodied hemin 18 the propony 01 and pmpnetay lo Rol ldoycc UImon, and .hall not. wlthoul pnw wmon

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00FA8-224 PAGE 10 OF 35

1 : Turbine to Compressor Coupling 2: Turbine Tiebolt 3: Turbine Tiebolt Nut 4: Turbine Splined Adapter

? '

Cracks within spline root due to flattenlng of segment to photograph wear pattems

A Metallurgical sectidning

- . - _ - I-̂ -. .,

Figure 3. Close up of Turbine to Compressor splines showing wear on the loaded side of the splines. Note: parts were reassembled after prior metallurgical sectioning. . M a p . 5X

PROPRIETARY RIGHTS LEGEND 7hm Ibchnical data and the Information embodlcd hcmn is the pmpm, of and pmpneuy IO RollcRoyc. Uia.on. and .hall not. wnhout p l l ~ r wmen PCmlUlOn of RollcRoycc Corpontlon be dmcloud In whola or In part to third parllQ& This lcgcnd .hall be includd on any rapdualon 01 thl. data an whole or m par( C o ~ n p h t 2 a . RollcRoyce Corpontlon (Unpubhhcdi

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L .ab

I

B

/

I /I!i jl;

Lab Break

Figzire4. Close up of Turbine to Compressor Coupling Splines after flattening and reassembly. Magn. 2.5X

PROPRIETARY RIGHTS LEGEND This IechnlCaI d a h and Iha inlomallon cmbodlut hemon IS Ihe pmp.ny 01 and pmpnctay to RollcRoyce Allomn and .hall not wnhout pnor wm.n p . m i w o n of RollcRoyce Cowmtion. be dtvlood in whole or in part to third wRin This I w n d .hall b. oncludut on any mproduc1ton 01 thlsdah ~n .,,&I. or tn pa; Copynght ?a. RollcRoycc C o w n i l o n (Unpuhlmhcd)

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00FA0-224 PAGE 12 OF 35

Figure 5 Close up of Turbine to Compressor Splines (Nos. 1-11) indicating witness marks (a & b) which are tabulated in Table II. Note: part was flattened during lab break. Arrow indicates smeared metal from corresponding Turbine Splined Adapter splines. Magn. 5.5X

PROPRIETARY RIGHTS LEGEND Thin Iechnicsl dab and the informatton embodled henon IS th. property 01 and pmpmby IO Roll.-Royc. *Illcon. and .hall not. wIthout pnor wnnm pcrmiuvon of Roll.-Royce Corporation. be disclosed In whole or In par( to lhtrd parlie& This legend shall be mcluded on m y nprodudlon 01 Ihls d a h In whole w In p.r( Copynghl Z m O - Rolla-!Aoyse Corponllon (Unpubloshed)

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00FA8-224 PAGE 13 OF 35

,

Figure 6. SEM image of Spline Nos. 1-11 showing comparatively lighter witness marks as compared with fragnented splines shown in Figure 7. M a p . 7.1X

PROPRIETARY RIGHTS LEGEND pcrmovlon 01 Rollc/)oyce Corponlaon, be d i u 1 4 tn whole or in p n to lhird perhes. This IegmId .hall b. mcludod on m y reprodunion 01 this daU in whole or In burl cwynghl ZOO0 - Rolls-Royca Corporation (Unpublmhed)

This Iechniul data and the ~nlorm~oon embodmd herein I. Ih. proprtv ol and pmpne1.y Io Rol ldoyce YItson. end .hdl not. without pnor W n U m

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00FA8-224 PAGE 14 OF 35

Figure 7. SEM image of Spline Nos. 17-23, 14&15 showing considerable fretting damage on the loaded side of the splines. Dashed lines indicate approximate location of wear depth measurements. M a p . 7.6X

PAOPRIETARY RIGHTS LEGEND This technical data and the inlormatdon embodled hcnln i st he prop.* 01 and pmpncury to Roll.-Roys. Nl~wn. and shall not without p n ~ r wmen p.r".uon 01 Roll.-Royce Corporation. be dmclo8ed in whole or In p r i lo third p a n m Thm I-nd shall ba included on any npmdua~on of thle d a h on whole or on p.ri Copynght 2000. Roll.Royce Corporation (Unpublished)

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00FA8-224 PAGE 15 OF 35

..-

Spline N O . ~ , M a p . 21.5X

Spline No. 12, M a p . 25X Figure 8. SEM image showing the comparatively light wear on Spline No.6 and heavier wear

on Spline No. 12.

PROPRIETARY RIGHTS LEGEND prmiulon 01 Rollc-Royce Corponroon. b. divlovd in whole or in par( lo third prtlm Thm I-nd .hall b. Included on any npmduclmn 01 thia data In whoh or in pan W n p M 2OOO - Rollc-Roycc Corporation (Unpublished)

This technical dab and the information embodied bmtn IS the p m p q of and pmpne1.y lo RollcRoycc Ulmm and dull not. rnhout pnor wmon

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00FAS-224 PAGE 16 OF 35

Spline No. 14, M a p . 22.5X

Spline Nos.19-20, M a p . 9.5X

Figure 9. SEM image documenting the condition of Spline Nos. 14, 19&20 with increasing amount of fretting on the loaded surface.

PROPRIETARY RIGHTS LEGEND permmuon of RollcRoyce Corpontlon. be disclosed In whole or In Pan to third partie8 This legend ahdl be inc1ud.d on any npmduction of lhm data in whole or in pa; C o p y n p h l ? ~ . Rolldoyce Corporation (Unpubliahsd)

This technical data and lha inlormanon cmbdnd herem IS the pmperty e4 snd pmpnetay to Rolldoycc Alllaon. and .hall not wlthoYl pnor wmcn

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00FA8-224 PAGE 17 OF 35

Magn. 9.6X

Magn. 7.5X

Figure 10. SEM image documenting the condition of Spline Nos. 20-21 (top) and 24- 26 (bottom). Note increasing fretting wear impressions from Turbine Tiebolt Nut on right side of images. Dashed lines indicate approximate locations of wear depth measurements.

PROPRIETARY RIGHTS LEGEND prmlmon of R o l l ~ o y c e Corponlion. be discloeed In whole or In part lo third partma Thm I w n d shall be Included on any npmducloan of 1ht.d.U on ;hole or m pi Copynghl2000. Roll.-Royce Corponllon (Unpubll.hed)

Thislechnlcd dala and the information embodled henln IS the pmprty of and pmpneby to Roll.-Roycc U11-n and .MI no( rlthout pnorrmnen

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Magn. 20X Figure 11. Lab-opened crack at the base of a spline (No. 22) showing fatigue crack growth.

Slotted rectangle indicates enlargement shown in photo at right. Whlte arrows indicate crack growth direction.

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00FA8-224 PAGE 19 OF 35

Figure 12. Fracture characteristics consistent with fatigue crack propagation.

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M a p . 35X

Figure 13. SEM image of circumferential fracture surface of splines (Nos. 18- 19) on Turbine to Compressor Coupling indicating the extent of fretting damage on the splines.

PROPRIETARY RIGWS LEGEND Thla technical d.1. and the infomatton embodled henin is the pmwrty of and pmpn.t.ry to RollcAoyce *Ila.on and h a l l not YlthoUt pnor wmen prmowon of RollcRoyce Corporalton. b. doulo.cd in whole or In pan to third pani.r Thia legend .hall be 8nclud.d on any reproductnon 01 thla dala tn whole or ~n pafl Copynghl *OM. ROl ldoyCe Corporation (Unpubhhcd)

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m m

cn a C

a, t Q c/)

.- -

"I1 I

k V " L n c u L o ~ L n 0 o m o c v o ~ o o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

(D

0

-e 0

cv 0

0

X'

- 5

F

- '3 c c

t . 0 c - I


Unetched, M a p . 50X

2% Nital, Ma&. 50X

Figure 15. Cross section of Turbine To Compressor spline (Nos.25-26) with crack at root showing straight propagation, characteristic of fatigue crack growth.

PROPRIETARY RIGHTS LEGEND Thialechntcd dah and the inlomatton embodled henm Islhc pmpcrty of and pmpncby IO Rol ldoysc Ul#.on. and .hall not. rnhoul pnorwntten pm8-n of Roll.-Roycc Corpomllon. be dtuloud In whole or in p n lo third p a n i n This Ibgend .hall be mcluded on any npmdunoon 01 Ihss dah en whol. or ~n p n CoWnphl 2 m . Roll.Aoycc CorpQnllon (Unpublwhd)

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. .

, . ~. ...

. .

. . . . . . . -

E€ d o PZ 3 3 V d PZZ-8VdOO

00FA8-224 PAGE 25 OF 35

M a g . 1.8X

Figure 17. Photos show the as-received condition of the Turbine Splined Adapter. The dashed line indicates the location of the metallurgical section within the damaged splines.

PROPRIETARY RIGHTS LEGEND Thm lechniul d.1. and the Information mbodled henin IS the propny of and propn.1.y io Roll.-Royce Nll.on and .hall nol. wllhout pnor rm.n prmluron of RollcRoyce Corponlwn. k dt%loYd tn whole or In part lo lhird panin This lagend shall b. tnc1ud.d on any mpmductoon 01 thm dah in w h d . 01 in p n W n g M ?Om - RollcRoycc Corpormon (Unpublished)

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00FA8-224 PAGE 26 OF 35

2. .

M a p . 50X Figure 18. SEM images documenting typical condition of splines on the Turbine Splined

Adapter.

PROPRIETARY RIGHTS LEGEND prmi.uon of Rol ldoyce Corponllon, be d i u l o u d in whole or In part lo third parli- This I-nd shall b. included on any mpmduaoon of thm dale in whole or in pa; Copynghl2OOO. RollMoyce Corporation (Unpubllshd)

Thin tuhnical dah and Ihe intormation ambodid harein 16 lha p m p q of and pmpnellry lo Rolldoyc. UIison. and shall not wtlhout pnw wmen

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00FA8-224 PAGE 27 OF 35

M a p . lOOX

Figure 19. Microstructural section showing the condition of the splines on the Turbine Splined Adapter.

PROPRIETARY RIGHTS LEGEND This technical data and the inlomatton *mbodted hem" IS the pmplty 01 and pmpnmry IO Roll.-Royc* U11.on and h a l l nat wnhoul pnor r m e n p.rml.uon 01 RollcRoyce Corporation be d i u l o u d In whole or in p r t to third p r t l n Thm I v n d ahall be included on m y npmductson 01 tho. dam 8" ;hole or an pi Copynght2ooo. RollcRoyce Corporation (Unpublmhdj

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00FA8-224 PAGE 28 OF 35

. . .~ . . . . . . . . . . . . .

. ,

. .

Figure 20. Microstructure of Turbine Splined Adapter showing nitrided case and silver plate (white) in top photo and quenched and tempered martensitic structure in bottom photo. Etchant: 2% Nital, Magn. 500X

PROPRIETARY RIGHTS LEGEND Th18 technical data and the inlormatim unbodied h w " IS the prop* 01 and pmpne1.y to RollcAoycc Uli.on. and .hall not. wlthoYt pnor w m u l p m l w o n 01 Roll.-RoYc~ Corporation. be d l a c l d In whole or In prl to third pnlM Th18 I-nd .halt be 1nclud.d on any nprodud~on d thm dah on whok 01 ~n prl CoWnght 2 M o . RollcRoyce Corpomon (Unpublmhed)

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00FAS-224 PAGE 29 OF 35

c

M a p . 0.95X

Figure 21. As received condition of the Spur Adapter Gearshaft

M a p . 1.25X

PROPRIETARY RIGHTS LEGEND This 1uhnic.l data and the mlom*loon embodled haman IS the prop* 01 and pmpne1.y IO Rolldoyc. Nl8.on. and .h.ll not. wnhout pnor wmen p r " . u o n 01 RollCRoYCe Corporalion. bc disclosed in whole or In prl to third panin This I-nd shall b. Includd on any npmduaton of tho. dab on whole o( In part w n g h t 2000. RollCRoyce Corponllon (Unpublmhed)

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00FA8-221 PAGE 30 OF 35

- -- 7- --” -

Figure 22.

-I 1’ Aft O-ring

- . - .

c

Close up of the forward and aft 0-Ring from the Spur Adapter Gearshaft showing damage on the aft O-ring consistent with compression against the splines. Arrows indicate damage.

PROPRIETARY RIGHTS LEGEND permmuon 01 Roll&oyce Corpontion. be d8ulos.d In whole or In pati to t h d psnm This I q n d ahall k included on any npmduclion 01 tho. dat8 ~n whole or In pati Copyright zmo - RollrRoyce Corpontlon (Unpublished)

This tnhn1c81 datB 8nd the inlormat#on embodied henm IS the pmprty 01 and propnetay to Aolldoyce A111.on and shall not wllhoY1 pnorwmm

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00FA8-224 PAGE 31 OF 35

Magn. 0.9X

Figure 23. As received condition of Turbine Tie Bolt. Bottom photo shows typical condition of Turbine Tiebolt Nut splines.

PROPRIETARY RIGHTS LEGEND This lechnlcnl d a h and the inlormallon nmbodld h*nln IS Ihe p m p q of and pmpnalary IO R o l l d o y u Nlo- and .hall nal, wlthoUI pnor wm*n permi.uon of RolldoYce Cowni lon. b. dl.cl& In whole or In p R lo third par l l r Thia I w n d .hall b. inc1ud.d on any npmdud~on of lhta data in who* or ~n p n Comnphl Ky)(I. Rolldoycc Cowmilon (Unpublmhld)

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00FA8-224 PAGE 32 OF 35

Magn. 0.6X

Magn. 0.8X

Figure 24. As received condition of the 1 St Stage Turbine Wheel. Dashed line indicates metallurgical section.

PROPRIETARY RIGHTS LEGEND This technical dah and the Inlormallon mbodled henm IS the property 01 and pmpnatary to Rolldoyce *Illson and shall not wllhovt pnor w n a n p.rmi.uon 01 Roll.-Royca Corporation be dimclod In whole or in part to third p . r t l ~ This I w n d shall be included on m y mproductoon of thm data I" &I. or on p i Copynpht Zoo0 - RollGloyce Corporation (Unpublmhed)

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00FA8-224 PAGE 33 OF 35

Figure 25. Microstructure of the 1'' Stage Turbine Wheel taken at the wheel rim showing acceptable structure. Etchant: MT, M a p . 3500X

PROPRIETARY RIGHTS LEGEND Thm technical d4U and the information embodmd hamin IS the prop.* of and pmpn.1.y to Rolldoyc. *Il~.on. and shall not. w n b a pnor wm.n Wrml-on of ROIICRoyce Corporatlon be dmcloud in whole or in p r l t o third p n l m Tho. I-nd shall b. mcludad on any mpductlon of Ihbs d.U tn whole or tn p.rl Copywht 2 m . RollcAoyca Corporatlon (Unpubleshadj

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00FA8-224 PAGE 34 OF 35

F

AFT

Figure 26. As received condition of 2"d Stage Turbine Wheel. Dashed line indicates metallurgical section. Magn. 0.6X

PROPRIETARY RIGHTS LEGEND Thin technical data and the intormallon embodled henun IS the property 01 and pmpnctay to Roiidoyce Ulfi.on and shall not wnhoYt pnor wmen prmluron 01 RokUoycc Corporation, be dieclosed in whole or In prl to third parties This legend shall be Included on m y npmdustion 01 tha.dsU on ~&lc or ~n p s i CoWnght ma,. Rol ldoyce Corpontlon (Unpublished)

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00FA8-224 PAGE 35 OF 35

M a g . 0.5X

M a g . 0.6X

Figure 27. As received condition of 1" Stage Nozzle. Dashed line indicates metallurgical section.

PROPRIETARY RIGHTS LEGEND Thm technical data and the inlonnallon embodled hcnln IS Ihc pmprty 01 and propnctary lo Rol ldoycc Mnl.on, and shall nol. without pnor w n n m prmlv lon of Rol ldoyce Corporallon, be diu1o.d In whole or In pan to third psnles This I q n d shall bc mcluded on any npmducllon 01 Ihm data I" whole or ~n p n Ccpynpht 2000. Ro l ldoycc Corporation (Unpublmhcd)

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