Cessna 150F N3376B accident near Ronan, Montana

Probable cause

A loss of engine power for reasons that could not be determined due to insufficient evidence.

NTSB analysis

The pilot departed on the cross-country flight with a planned touch-and-go landing at an intermediate airport about 8 miles from the origination airport. The pilot reported that he applied carburetor heat for the approach and landing at the intermediate airport. After touchdown, in accordance with the operating procedures, the pilot retracted the flaps, shut off the carburetor heat, and applied full throttle for the takeoff and climbout. The engine began to lose power when the airplane had gained about 350 ft; the pilot reported that the low altitude prevented him from conducting any emergency procedures except to select an emergency landing location in a field. He did not apply carburetor heat or extend the flaps. The airplane struck a berm in the field, which caused it to nose over inverted and resulted in substantial damage.

A postaccident examination of the engine initially revealed incomplete valve seating in one of the forward-most cylinders. Once the valves were staked, the valve seating was normal, so the initial abnormality was attributed to impact. The engine examination did not reveal any evidence of preimpact mechanical anomalies or deficiencies that would have resulted in the loss of power. Although carburetor icing envelope charts indicated the possibility of carburetor icing at glide power, the pilot's use of carburetor heat on the approach, the loss of power with the throttle set at takeoff power, and the ambient conditions were all consistent with a low likelihood of carburetor icing. Because detailed postaccident examination was limited to the engine, the investigation was unable to eliminate the possibility that an airframe or carburetor fuel delivery problem or water contamination of the fuel resulted in the engine power loss.

Text from the NTSB. Open the NTSB docket for WPR14LA232 for the full record.