Ercoupe 415 N331BW accident near Ardmore, Oklahoma

Probable cause

The pilot’s improper decision to takeoff with 3 persons in a 2-place airplane and over maximum gross weight, and his failure to apply carburetor heat when the airplane’s engine experienced carburetor ice and a partial loss of power.

NTSB analysis

The pilot was performing a local flight with two passengers onboard the two-seat airplane. After flying two passes over a house, the pilot felt a “slight shudder” and thought the airplane had flown through its own propeller wash. The engine then started to vibrate, and the pilot was not able to control the vibration by adjusting the throttle. The pilot set the airplane up in a glide configuration at which time the airplane banked to the left. The pilot applied full right aileron control, but it did not stop the left turn. The pilot was attempting to land the airplane in a field when it contacted a tree and came to rest inverted.

A postaccident examination revealed no preimpact mechanical malfunctions or failures with the airframe, including the flight controls, and engine that would have precluded normal operation. It was determined that the airplane was 48 pounds over its maximum gross weight when the pilot started the engine. A review of local area meteorological data showed that at the time of the accident, the airplane was likely operating in conditions conducive to the formation of serious icing conditions (at cruise power). The pilot reported he did not apply the carburetor heat when the engine began to lose power.

It is likely the engine sustained a partial loss of engine power in flight due to the formation of carburetor icing, which resulted in the attempted forced landing.

Text from the NTSB. Open the NTSB docket for CEN21LA047 for the full record.