ASN Wikibase Occurrence # 356756
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| Date: | Sunday 1 September 1996 |
| Time: | 15:05 LT |
| Type: |  Piper PA-28-161 |
| Owner/operator: | Vernair |
| Registration: | N4366Y |
| MSN: | 28-8416053 |
| Year of manufacture: | 1984 |
| Total airframe hrs: | 8453 hours |
| Engine model: | Lycoming O-320-D3G |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Skwentna, AK -
 United States of America
|
| Phase: | En route |
| Nature: | Unknown |
| Departure airport: | Anchorage, AK (MRI) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot & 2 passengers departed on a local area sightseeing flight. While in cruise flight at about 4,000 ft, the engine developed a vibration, then lost power. Oil spray was deposited on the windshield. The pilot performed an emergency landing on a sand bar. After landing, he noticed that the entire propeller, propeller flange, & the outboard end of the engine crankshaft were missing from the engine. Examination of the engine revealed evidence of fatigue cracking, emanating from a corrosion pit on the inner diameter surface of the crankshaft bore. Numerous other corrosion pits were found adjacent to the fracture origin. The engine manufacturer reported the engine was built & shipped from the factory on 4/13/81. The engine was the subject of a mandatory service bulletin (S/B), dated 1018/94, that addressed the inspection of the inside bore of the crankshaft for the presence of corrosion. The S/B required that an initial inspection be conducted within the next 200 hrs of operation or 1 year from the date of the S/B. The operator's company manual stated the Director of Maintenance shall ensure that current manufacturer's mandatory S/B's were complied with. No record of compliance with the S/B was noted in the engine maintenance records.
Probable Cause: corrosion and subsequent fatigue failure of the crankshaft, which resulted in engine failure and a forced landing. Factors related to the accident were: the lack of suitable terrain for a forced landing, and the operator's non-compliance with a service bulletin.
Accident investigation:
 |
|
Sources:
NTSB ANC96LA140
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Mar-2024 10:36 | ASN Update Bot | Added |
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