Beech B36TC accident near Lemoore, California, August 14, 2011
On August 14, 2011 at about 11:00 pm local time, a Beech B36TC, registered N6465X, was substantially damaged in an accident during enroute (cruise) near Lemoore, California (Lemoore Naval Air Station airport). It was a personal flight under general aviation rules (Part 91). No one was hurt; 3 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A loss of engine power during cruise flight due to maintenance personnel's failure to adequately torque the number 4 cylinder retaining nuts, which resulted in the in-flight separation of the cylinder.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 14, 2011 · about 11:00 pm local time
- Place
- Lemoore, California · Lemoore Naval Air Station · map
- Type
- Accident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Beech B36TC · all B36TCs on the register
- Registration
- N6465X · no longer on the register · serial EA-306
- 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 at cruise altitude, the engine experienced a partial loss of engine power. The pilot requested to land, and then heard a loud noise, followed by the engine cowling opening, and the pilot noted something fly out of the engine compartment followed by a total loss of engine power. Unable to reach the airport, the pilot subsequently made a forced landing in a plowed field. Postaccident examination of the engine revealed that the number 4 cylinder and piston had separated from the engine in flight and likely departed through the open engine cowling. The crankcase had mechanical damage concentrated at the number 4 and 6 cylinder bay areas. The number 4 cylinder bay area had missing crankcase material, with rubbed and displaced material noted on the cylinder attachment area. Further examination of the remaining cylinders found that the retaining self-locking nuts were loose and had not been tightened or properly torqued. Review of maintenance records noted that the engine had been overhauled less than 40 flight hours before the accident. It is likely that maintenance personnel did not properly tighten the self-locking nuts for the number 4 cylinder, which subsequently led to its separation.
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 (cruise) defining event
- Off-field or emergency landing during emergency descent
- Collision with terrain or object (not controlled flight into terrain) during emergency descent
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng cyl section › Failure
- cause Personnel issues › Task performance › Maintenance › Replacement › Maintenance personnel
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 1,520 hours in all; 682 in this make and model; 9 in the last 90 days; 5 in the last 30 days; 1,434 as pilot in command
- Last flight review: September 1, 2010
- Medical certificate: Class 3 (without waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 2,364 hours
- Last inspection: annual inspection, August 16, 2010; 40 hours since
- Maximum gross weight: 3,850 lb
- Seats: 6
- Landing gear: fixed
- Engine: Cont Motor TSIO-520 SER (piston); 0 hours total
The flight
- Departed from: UDD Bermuda Dunes CA at 9:30 pm
- Destination: C83 Byron CA
- Flight plan: VFR
Weather at the time
- Light: daylight
- Wind: from 340° at 12 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 99°F (37°C), dew point 34°F (1°C)
- Altimeter: 29.81 inHg
- Observation at 11:11 pm from NLC, 2 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 2 |
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.