Beech 77 N1802Y accident near Leesburg, Florida

Probable cause

A partial loss of engine power due to carburetor icing, which resulted from the flight instructor's decision not to use carburetor heat.

NTSB analysis

The flight instructor was performing a checkout flight with the commercial pilot. They completed about 30 minutes of air work before returning to the airport to practice takeoffs and landings. The first landing was normal, and the commercial pilot added power to take off. When the airplane reached an altitude of 400 ft above the ground, the engine lost partial power and the airplane began to descend. The flight instructor took control of the airplane and landed in trees and a swamp adjacent to the airport. Examination of the engine revealed that it was full of water and debris from immersion in the swamp; however, no mechanical discrepancies were identified that would have precluded normal operation at the time of the accident.

A carburetor icing probability chart indicated that the airplane was operating in an environment associated with a serious risk of carburetor ice accumulation at glide power settings. The flight instructor stated that they did not use carburetor heat before landing because the carburetor heat caused the engine to run very rough when applied. Given that a postaccident examination of the engine revealed no mechanical issues with the engine, and the flight instructor stated that the carburetor heat was not being used during the flight while operating in an environment that was conducive to carburetor icing, the loss of engine power was most likely due to carburetor ice that accumulated during the approach.

Text from the NTSB. Open the NTSB docket for ERA19LA217 for the full record.