ERA14LA401 · Cessna 150G

The private pilot reported that he had flown the airplane to another airport earlier in the day and was returning to his home airport. The pilot stated that, when the airplane entered the downwind leg of the traffic pattern, he applied carburetor heat and 10 degrees of flaps. He added that, when he turned the airplane onto the base leg of the traffic pattern, he noticed an "unusually" low airspeed. The engine did not respond to throttle adjustments, so the pilot secured the carburetor heat, which had no effect. He then turned the airplane onto the final approach, and the propeller stopped. The pilot subsequently performed a forced landing to a cornfield, during which the right wing spar and propeller sustained substantial damage.

A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. A small amount of water was observed in the gascolator. The pilot reported that, when he initially sumped fuel before the first flight, he saw about 2 inches of water in a "standard" sump tube. The pilot also noted an additional 1/4 inch of water after adding 8 gallons of fuel. He further noted another 1/2 inch of water after adding 5 more gallons at the intermediate airport.

Given the reported water in the fuel system before the first flight and after adding additional fuel, it is possible that water could have built up over time in the carburetor bowl and entered the engine as the airplane was making a descending turn. However, it is also possible that carburetor ice had formed given that the temperature and dew point at the time of the engine stoppage were conductive to serious carburetor icing at glide power. The pilot did not note if the engine rpm (fixed-pitch propeller) had decreased slowly but did note that the airspeed had decreased, indicative of lower rpm and, therefore, possibly carburetor icing. Also, although the pilot added carburetor heat in the landing pattern, with previously reduced power for the descent, carburetor ice could have already formed or the engine could have cooled to the point that initial heating efforts would not have provided heated air. However, with no substantive evidence that carburetor ice had formed and given the small amount of water found in the gascolator, the reason for the total loss of power could not be determined.

Verbatim NTSB analysis and probable cause from the NTSB dataset