On April 4, 2013, about 1640 mountain daylight time, an RV-6A airplane, N525PW, experienced a loss of engine power and conducted a forced landing near Spearfish, South Dakota. The private rated pilot and flight instructor received minor injuries and the airplane was substantially damaged. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight that operated without a flight plan. The flight originated from the Black Hills Airport – Clyde Ice Field, Spearfish, South Dakota, about 1630.

According to the pilot, he had recently purchased the airplane and was flying the airplane back to his home airfield. After stopping at an en route airport for fuel, they departed, and were climbing through 6,000 feet when the engine suddenly lost power. The pilot added that he switched on the auxiliary fuel pump and ignition system; however, the engine did not restart. He then selected a pasture for the forced landing. During landing, the nose gear collapsed and the airplane came to rest inverted.

The responding Federal Aviation Administration (FAA) inspector examined the airplane on site and noted that the airplane’s fuselage and vertical stabilizer sustained substantial damage during the accident. The airplane was equipped with an automotive Chevrolet 4.6L engine adapted for aviation use. Further examination of the engine revealed that the carburetor’s air filter was dirty and partly clogged. Additionally, a wire that runs from the coil to the distributor was found disconnected from the coil terminal. The wire and distributor were the automotive type and had the traditional terminal male/female plug arrangement, without an additional locking mechanism.