Shortly after takeoff on an extended crosswind leg about 800 feet mean sea level, the RV-4’s engine lost total power.
The pilot continued ahead and landed in a field near Butler, Pennsylvania. During the landing, the plane hit a wire fence and brush, which resulted in substantial damage to the fuselage and wings.
During post-accident interviews, the pilot reported that this was the first flight after he had made maintenance repairs to the automobile-converted engine due to an engine failure one month before the accident. He stated that he installed an aftermarket engine control unit and modified the fuel delivery software, which resulted in the engine running too lean for flight and likely caused detonation and piston damage to occur.
During the run-up before the accident flight, he was aware that the engine was not producing power as it should. However, he decided to depart with a known engine problem, and his decision to do so led to the accident.
Probable cause: The pilot’s improper decision to fly the airplane with a known engine problem and his improper modification of the engine control unit fuel delivery software, which led to the engine running too lean and resulted in a total loss of engine power during climb.
NTSB Identification: ERA18LA163
This June 2018 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.