ASN Wikibase Occurrence # 89272
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| Date: | Thursday 20 January 2011 |
| Time: | 13:17 |
| Type: |  Piper PA-28-235 Cherokee |
| Owner/operator: | Private |
| Registration: | N8608W |
| MSN: | 28-10124 |
| Year of manufacture: | 1963 |
| Total airframe hrs: | 3505 hours |
| Engine model: | Lycoming O-540 SERIES |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | San Luis Obispo, California -
 United States of America
|
| Phase: | Approach |
| Nature: | Private |
| Departure airport: | San Luis Obispo, CA (SBP) |
| San Luis Obispo, CA (SBP) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot reported that, while on approach to the runway, the vacuum pump failed, then the engine lost power. The pilot initiated a forced landing to a field, and the airplane impacted multiple metal poles. Postaccident examination of the engine revealed that the left magneto drive gear and the left idler gear shaft were separated from their mount. Both of the attachment bolts for the left idler gear shaft were separated from the crankcase, and their respective bolt bores were elongated. One of the attachment bolts for the left idler gear shaft was fractured, and metallurgical examination revealed that the fracture surface was consistent with fatigue. Metallurgical analysis determined that the fatigue was due to a lack of sufficient preload on the bolts. Maintenance records showed that the last logged maintenance activity in which the bolts could have been manipulated was performed about 20 years before the accident. The engine had accumulated about 1,400 operating hours since that time.
Probable Cause: The loss of engine power due to the fatigue fracture of one attachment bolt for the left idler gear shaft, which resulted from an insufficient preload on both attachment bolts.
Accident investigation:
 |
|
Sources:
NTSB
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 20-Jan-2011 20:47 | bizjets101 | Added |
| 06-Jul-2011 13:44 | hggultek | Updated [Registration, Narrative] |
| 06-May-2012 11:31 | harro | Updated [Aircraft type, Narrative] |
| 21-Dec-2016 19:25 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 26-Nov-2017 18:46 | ASN Update Bot | Updated [Cn, Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative] |
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