ASN Wikibase Occurrence # 354499
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Date: | Sunday 10 May 1998 |
Time: | 12:20 LT |
Type: | North American Sabreliner 65 |
Owner/operator: | Mallinckrodt Group Inc. |
Registration: | N651MK |
MSN: | 465-73 |
Year of manufacture: | 1981 |
Total airframe hrs: | 7183 hours |
Engine model: | Garrett TFE 731-3R-1D |
Fatalities: | Fatalities: 0 / Occupants: 8 |
Aircraft damage: | Minor |
Category: | Serious incident |
Location: | Palm Springs, CA -
United States of America
|
Phase: | Take off |
Nature: | Executive |
Departure airport: | , CA (KPSP) |
Destination airport: | St Louis, MO (KSTL) |
Investigating agency: | NTSB |
Confidence Rating: | Accident investigation report completed and information captured |
Narrative:An uncontained engine failure occurred during the takeoff roll. The high pressure centrifugal impeller disk had burst, with one chunk exiting through the engine cowling. The melt and forging records for the disk were reviewed and met the required specifications, including alloy chemistry. Metallurgical examination of the disk revealed subsurface primary and secondary fatigue cracks near an area that had been reworked to remove LCF stresses in accordance with a Service Bulletin. The cracks were located opposite of each other in the seal relief undercut area. The primary fatigue origin was below the shot-peened surface near a high stress area and the secondary fatigue origin remained subsurface, with the propagation of both cracks running parallel to the surface until overload separation. The primary fracture surface could not be definitively analyzed due to plasticity and the presence of an oxide layer. No melt, forging-related or heat-treating defects were found in the vicinity of the fatigue origins; however, subsurface LCF was present. No significant hardness difference was found either in or away from the fatigue origins. There was no evidence of a subsurface occlusion. A physical resemblance between the fatigue origin and the zones of crystallographically aligned phase (texture zones) was observed in the microstructure. The shape and orientation of the origin macrostructure and/or texture may have been a contributing factor to crack initiation; however, no precipitating event or cause for the fatigue initiation was identified. Analysis reverified the Service Bulletin rework specifications, confirming that residual stress was negligible at the depth of crack initiation.
Probable Cause: the fatigue failure and uncontained separation of the high pressure impeller in the No. 2 engine during the takeoff roll. While the impeller showed evidence of a subsurface fatigue origin, the percipient cause of the separation was not definitively determined.
Accident investigation:
|
| |
Investigating agency: | NTSB |
Report number: | LAX98IA158 |
Status: | Investigation completed |
Duration: | 2 years and 6 months |
Download report: | Final report |
|
Sources:
NTSB LAX98IA158
History of this aircraft
Other occurrences involving this aircraft
29 June 2023 |
N651MK |
My Jet Inc. |
0 |
Augusta-Bush Field, GA (AGS/KAGS) |
|
non |
Location
Revision history:
Date/time | Contributor | Updates |
11-Mar-2024 15:00 |
ASN Update Bot |
Added |
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