Accident Details
On July 4, 2011, at approximately 1300 Eastern Daylight Time, a Cessna 150L (registration N150ET) operated by a private individual was substantially damaged during a forced landing into a cranberry bog. The aircraft had just departed from Plymouth Municipal Airport in Plymouth, Massachusetts. The pilot, who held a commercial certificate, was not injured. The personal flight was conducted under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the planned local flight.
Engine Power Loss
During the 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 landing gear, propeller, and engine firewall sustained substantial damage. The pilot stated that the loss of engine power was due to a stuck cylinder valve.
Post-Accident Examination
A Federal Aviation Administration (FAA) inspector examined the engine and found that the No. 2 cylinder intake and exhaust valve springs exhibited corrosion and carbon deposits. The other cylinder valve springs also exhibited corrosion, consistent with lack of operation, but did not exhibit the carbon build-up similar to the No. 2 cylinder valve springs. The inspector also checked the fuel system, cylinder compression, sparkplugs, carburetor, and exhaust system, and noted no other defects.
Maintenance History
According to maintenance records, the airplane had operated for 17 hours since its most recent annual inspection, which was performed on August 14, 2010. The engine had operated for 256 hours since its most recent overhaul, which was completed more than 10 years prior to the accident.
Previous Incident
Review of FAA records revealed that the same airplane was involved in a forced landing to a cranberry bog in 2003, due to a stuck cylinder valve.