Piper PA24 N7639P accident near Nashville, Tennessee

Probable cause

The pilot’s failure to use carburetor heat during the approach, which resulted in a loss of engine power due to carburetor icing.

NTSB analysis

The private pilot had completed most of a cross-country flight and about 7 miles from the destination airport during the approach, the engine lost all power. Despite several troubleshooting actions, the pilot was unable to restore engine power. He subsequently completed a forced landing in a field where the airplane touched down hard resulting in substantial damage to the fuselage and both wings. A postaccident examination of the airplane and engine found no evidence of mechanical malfunctions or failures that would have precluded normal operation and the fuel tanks were not breached.

A carburetor icing probability chart revealed that serious icing was to be expected at glide power. The pilot had not used carburetor heat within the preceding 30 minutes prior to the loss of engine power, and he could not recall using carburetor heat after the loss of engine power.

Additional examination of the airplane found about 7 gallons of fuel in the left fuel tank, which was the reported tank selected at the time of the engine failure. About 1/4 to 1/8 of a cup of fuel was found in the right tank, which was the tank the pilot switched to after the engine failure. Trace amounts of fuel were located throughout the fuel lines and carburetor.

Given that sufficient fuel was found in the tank that was selected when the loss of power occurred, it is likely that the accumulation of carburetor resulted in a total loss of engine power. In addition, after the loss of engine power, the fuel selector was switched to a tank that was found to have an unusable amount of fuel, which further reduced the possibility that engine power could be restored.

Text from the NTSB. Open the NTSB docket for ERA21LA070 for the full record.