Cessna 150L accident near Plymouth, Massachusetts, July 4, 2011
On July 4, 2011 at about 5:00 pm local time, a Cessna 150L, registered N150ET, was substantially damaged in an accident during initial climb near Plymouth, Massachusetts (Plymouth 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
A partial loss of engine power during initial climb due to a stuck cylinder valve, which resulted from excessive corrosion and carbon deposits on the valve springs due to inadequate maintenance.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 4, 2011 · about 5:00 pm local time
- Place
- Plymouth, Massachusetts · Plymouth · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 150L · all 150Ls on the register
- Registration
- N150ET · no longer on the register · serial 15073072
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
During initial climb, the engine began to run rough and experienced a partial loss of power. The pilot elected to land straight ahead into a cranberry bog. The pilot believed the loss of engine power was due to a stuck cylinder valve. Postaccident examination of the engine revealed that the No. 2 cylinder intake and exhaust valve springs exhibited excessive corrosion and carbon deposits, consistent with lack of use, which made them more susceptible to sticking. The extent of the corrosion was such that it presented over a long period of time and should have been addressed during routine maintenance. No other defects were noted with the engine that would have resulted in a partial loss of power. The airplane had been operated for 17 hours since its most recent annual inspection, which was completed 11 months prior to the accident. The engine had been operated for 256 hours since its most recent overhaul, which was completed more than 10 years prior to the accident. The same airplane was involved in a forced landing to a cranberry bog 8 years earlier due to a stuck cylinder valve.
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
- Powerplant sys/comp malf/fail during initial climb defining event
- Loss of engine power (partial) during initial climb
- Off-field or emergency landing during emergency descent
- Collision with terrain or object (not controlled flight into terrain) during landing
The NTSB's findings
- cause Personnel issues › Task performance › Maintenance › (general) › Not specified
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng cyl section › Fatigue/wear/corrosion
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng cyl section › Malfunction
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: single-engine land; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane; rotorcraft: helicopter
- Flight time: 4,327 hours in all; 3,001 in this make and model; 44 in the last 90 days; 20 in the last 30 days; 4,023 as pilot in command; 3,000 on instruments
- Last flight review: February 17, 2011
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 4,500 hours
- Last inspection: annual inspection, August 14, 2010; 17 hours since
- Maximum gross weight: 1,500 lb
- Seats: 2
- Landing gear: fixed
- Engine: Cont Motor O-200 (piston); 0 hours total
The flight
- Departed from: PYM Plymouth MA at 5:00 pm
- Destination: PYM Plymouth MA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 280° at 11 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 84°F (29°C), dew point 64°F (18°C)
- Altimeter: 29.79 inHg
- Observation at 4:52 pm from PYM
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.