NTSB Factual Report

On February 17, 2011, about 1715 eastern standard time, a Cessna 150H, N7237S, operated by a private individual, was substantially damaged during a forced landing to a field, following a partial loss of engine power during takeoff from a private airstrip near Jonesborough, Tennessee. The certificated private pilot was not injured. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the planned local flight.

The pilot reported that his airplane sat for approximately 1 month prior to the accident flight, with its wing fuel tanks about one-quarter full. Prior to the accident flight, the pilot's preflight inspection included sumping the fuel tanks, and he thought he had removed all water and rust flake contamination from the fuel tanks.

The airplane subsequently departed on runway 27, which was approximately 1,400 feet long, 40 feet wide, and consisted of turf. During takeoff, about 40 feet above the ground, the engine began to run rough. The pilot cycled the throttle control several times, and the engine power seemed to oscillate. Since the engine continued to produce partial power, the pilot attempted a 180-degree turn back to the airport; however, the airplane impacted a field west of the airport and came to rest inverted.

The pilot stated that although he sumped the fuel tanks during the preflight inspection, some contamination may have remained in the fuel.

Examination of the wreckage by a Federal Aviation Administration (FAA) inspector revealed damage to both wings, the vertical stabilizer, and the firewall. The inspector planned to further document the fuel once the airplane was recovered from the field and fuel could be drained from it.

A subsequent examination was performed the following day by a mechanic, under the direction of the FAA inspector. The mechanic sumped the fuel tanks and noted that the first two samples had a small amount of rust particles and debris, which he stated was consistent with an airplane being in an accident. He then drained the gascolator, found no contamination of the fuel and the gascolator screen was clean. The fuel line from the gascolator to the carburetor was absent of contamination. The finger screen from the carburetor contained a few rust particles, but the mechanic further stated that it was not enough to affect fuel flow. The mechanic then removed the carburetor from the engine, cycled the throttle arm, and fuel sprayed from the accelerator pump. He opened the carburetor and found a small amount fuel in the bowl, which was also absent of contamination. The float, needle and seat were intact and operated properly.

The reported weather at airport located about 15 miles northeast of the accident site, about the time of the accident, included clear skies, wind from 270 degrees at 8 knots, temperature 21 degrees Celsius (C), and dew point 4 degrees C.

Review of an FAA Carburetor Icing Envelope chart revealed "Serious Icing - Glide Power" for the given temperature and dew point.

NTSB Probable Cause

A partial loss of engine power during initial climb for undetermined reasons.