Amateur-built STOL CH 750 N750AZ accident near Waynesburg, Pennsylvania

Probable cause

The partial loss of engine power due to carburetor icing.

NTSB analysis

The flight instructor and student pilot were conducting a local instructional flight. Following uneventful touch-and-go-landings and a refueling, the student pilot and flight instructor departed again. Shortly after departure, the engine began to vibrate and lose power. The flight instructor took control of the airplane and landed straight ahead. During landing, the airplane impacted a row of tractor tires.

Postaccident examination of the engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The atmospheric conditions at the time of the accident were conducive to the accumulation of carburetor icing. The flight instructor stated that he applied carburetor heat once he noted the drop in rpm. After applying carburetor heat and noting the continued loss of rpm, he turned off the carburetor heat to reduce the loss of rpm and to extend the airplane's glide range. Rapid ice accumulation would have required the carburetor heat to be on for a longer period of time to fully melt the ice and restore full power to the engine. Therefore, it is likely that the carburetor accumulated ice during departure, which resulted in the partial loss of engine power and vibration during the subsequent climb.

Text from the NTSB. Open the NTSB docket for ERA16LA270 for the full record.