Accident Overview
On June 7, 2018, about 1100 eastern standard time, an experimental amateur-built Vans Aircraft RV-4, registration N7765X, was substantially damaged during a forced landing shortly after takeoff from Pittsburgh/Butler Regional Airport (BTP) in Butler, Pennsylvania. The private pilot, who was the sole occupant, sustained minor injuries. The personal flight was conducted under Part 91 of Title 14 Code of Federal Regulations in visual meteorological conditions; no flight plan was filed.
Pilot's Account
According to the pilot, after takeoff from runway 26, while flying on an extended crosswind traffic pattern leg at about 800 ft mean sea level, the engine lost total power. He continued ahead, maintained best glide speed, and landed in a field. During the landing, the airplane impacted a wire fence and brush, resulting in substantial damage to the fuselage and wings.
The pilot reported that this was the first flight after maintenance repairs he had performed on the airplane's automobile-converted engine, following a prior engine failure about one month earlier. During the repair, he replaced all four pistons. He also stated that he had installed an aftermarket engine control unit (ECU) and modified the fuel delivery software to lean the fuel-to-air mixture for improved engine starts. Regarding the accident flight, the pilot said: "The cause of the engine failure was my entering a bad tune which caused the engine to run lean under high load. Detonation occurred and caused a piston to melt halting the engine."
Additional Information
A Federal Aviation Administration inspector noted that the pilot reported previously "burnt through a piston" with this engine during flight. The pilot also stated that during the run-up on the day of the accident, the engine was "not as strong" as it should have been, but he decided to fly anyway.
The pilot held a private pilot certificate with a single-engine land rating and a repairman experimental aircraft builder certificate limited to inspection of the accident airplane. He reported 420 total flight hours, including 90 hours in the accident make and model. His most recent Basic Medical requirements were completed in June 2017, and his last flight review was in July 2017.
The two-seat, low-wing, fixed landing gear, single-engine airplane was manufactured in 2015. It was equipped with an automobile-converted, fuel-injected, General Motors Ecotec L61, 142-horsepower engine.
Weather Conditions
At 1056, BTP reported variable wind at 3 knots, visibility 10 statute miles, clear skies, temperature 17°C, and dew point 10°C.