Piper PA-28-235 accident near San Luis Obispo, California, January 20, 2011
On January 20, 2011 at about 9:17 pm local time, a Piper PA-28-235, registered N8608W, was substantially damaged in an accident during landing (flare/touchdown) near San Luis Obispo, California (San Luis County Airport). It was a personal flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- January 20, 2011 · about 9:17 pm local time
- Place
- San Luis Obispo, California · San Luis County Airport · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Piper PA-28-235 · all PA-28-235s on the register
- Registration
- N8608W · no longer on the register · serial 28-10124
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Loss of engine power (total) during enroute (descent)
- Off-field or emergency landing during landing
- Collision with terrain or object (not controlled flight into terrain) during landing (flare/touchdown) defining event
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng rear section › Fatigue/wear/corrosion
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng rear section › Malfunction
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 2,029 hours in all; 1,027 in this make and model; 15 in the last 90 days; 5 in the last 30 days; 1,874 as pilot in command
- Last flight review: March 23, 2010
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 3,505 hours
- Last inspection: annual inspection, March 23, 2010; 46 hours since
- Maximum gross weight: 2,900 lb
- Seats: 4
- Landing gear: retractable
- Engine: Lycoming O-540 SERIES (piston); 0 hours total
The flight
- Departed from: SBP San Luis Obispo CA at 7:30 pm
- Destination: SBP San Luis Obispo CA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 72°F (22°C), dew point 45°F (7°C)
- Altimeter: 30.07 inHg
- Observation at 8:56 pm from SBP, 1 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.