ASN Wikibase Occurrence # 290623
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| Date: | Monday 5 May 2014 |
| Time: | 13:30 LT |
| Type: |  Cessna T207A |
| Owner/operator: | Aero-graphics Inc |
| Registration: | N323JC |
| MSN: | 20700494 |
| Year of manufacture: | 1978 |
| Total airframe hrs: | 9330 hours |
| Engine model: | Continental TSIO-520-M |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Rock Springs, Wyoming -
 United States of America
|
| Phase: | En route |
| Nature: | Executive |
| Departure airport: | Evanston Airport, WY (EVW/KEVW) |
| Rock Springs-Sweetwater County Airport, WY (RKS/KRKS) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The commercial pilot reported that, during the business flight, while about 9,500 ft mean sea level, the engine lost all power. The pilot was unable to restart the engine and realized that the airplane would not be able to reach the airport, so he initiated a forced landing in a nearby clearing.
Examination of the engine revealed that the No. 2 main bearing had separated from the bearing support. The No. 2 main bearing support exhibited evidence of bearing shift. The No. 2 main bearing support mating surfaces displayed fretting damage, consistent with the application of insufficient torque on the cylinder through bolts. Further, the breakaway torque on the Nos. 1 and 2 cylinder through bolts were below specifications. It is likely that the insufficient torque on the Nos. 1 and 2 through bolts resulted in the fretting damage, the No. 2 main bearing shifting, and the subsequent separation of the crankshaft.
Further examination of the engine revealed that the No. 2 cylinder piston was labeled as a piston for a naturally aspirated engine, whereas the other pistons were labeled for a turbocharged engine, which the airplane was equipped with. No additional anomalies were observed with the airframe and engine that would have precluded normal operation.
A review of maintenance records revealed that the No. 1 cylinder was replaced 94.5 hours before the accident, which would have required the removal and installation of the Nos. 1 and 2 cylinder through bolts. It is likely that maintenance personnel applied insufficient torque on the Nos. 1 and 2 cylinder through bolts during the reinstallation of the No. 1 cylinder.
Probable Cause: Maintenance personnel's application of insufficient torque to the engine cylinder through bolts during replacement of the No. 1 cylinder, which resulted in the displacement of the No. 2 main bearing, the bearing shifting, and a catastrophic engine failure.
Accident investigation:
 |
|
Sources:
NTSB WPR14LA240
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 06-Oct-2022 17:24 | ASN Update Bot | Added |
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