Cessna 152 N48761 accident near Turlock, California

Probable cause

The loss of engine power due to carburetor icing resulting from the pilot's failure to apply carburetor heat. Contributing to the accident was the instructor's inadequate supervision of the flight.

NTSB analysis

The flight instructor and student were performing a series of touch-and-go pattern operations. The instructor reported that the engine lost power during the initial climb. He took control of the airplane from the student and verified that the mixture was fully enriched and the fuel shut off valve was in the "on" position. These actions had no effect, so he executed a forced landing in a nearby field. During the landing roll, the nosewheel sunk into the soft ground and the airplane nosed over and came to rest inverted. A postaccident examination of the engine by a licensed airframe and powerplant mechanic revealed that the bottom spark plugs of the number one and four cylinders exhibited evidence of water. Water was observed within the fuel sump; however, no water contamination was found in the fuel drained from the airplane's tanks. The engine was successfully run at various speeds with no anomalies noted. Review of the carburetor ice probability chart revealed that the temperature and dew point near the time of the accident were conducive to serious icing at any power setting. The instructor did not report applying carburetor heat following the engine failure.

Text from the NTSB. Open the NTSB docket for WPR09LA117 for the full record.