Aeronca 7AC N82658 accident near Spring City, Tennessee

Probable cause

The pilot's failure to properly apply carburetor heat in conditions conducive to carburetor icing, which resulted the accumulation of carburetor ice and the subsequent total loss of engine power.

NTSB analysis

The private pilot was returning the airplane to his home airport following maintenance. During the flight, as the airplane approached the destination airport and when the pilot applied climb power to clear terrain, the engine started sputtering and losing rpm. He subsequently applied carburetor heat, the engine rpm increased, and the airplane climbed momentarily. The engine then started sputtering again, and this time, the pilot applied carburetor heat, but it had no effect, and the engine then lost total power. Despite other efforts to restore engine power, the engine did not restart, so the pilot performed a forced landing to a field, during which the right main landing gear collapsed and the right forward wing strut sustained substantial damage.

During a postaccident test-run, the engine operated normally with no anomalies noted, and an examination of the engine revealed no evidence of any preaccident mechanical malfunctions or failures that would have precluded normal operation. The atmospheric conditions about the time of the accident were conducive to moderate carburetor icing at cruise engine power settings and serious icing at descent power. Therefore, given the evidence, it is likely that, because the pilot did not apply carburetor heat until after the engine began losing power, carburetor ice accumulated, which resulted in the loss of engine power.

Text from the NTSB. Open the NTSB docket for ERA15LA183 for the full record.