CEN19LA226

The pilot was conducting a local flight to ensure that the airplane was operating normally for an upcoming trip. While returning to the airport, the engine experienced a loss of power and the airplane was unable to maintain altitude. The pilot conducted a forced landing to a corn field, during which the airplane nosed over and came to rest inverted. The pilot later examined the engine and determined that one of the engine's electrical switch boxes had an open circuit, which prevented electrical charge from reaching the cylinder Nos. 1, 3, and 5 spark plugs. The other switch box, which provided charge to the Nos. 2, 4, and 6 spark plugs, operated normally. It is likely that the loss of engine power was the result of the open circuit and subsequent lack of ignition to three cylinders.

On July 16, 2019, about 1845 central daylight time, an experimental Super Acro Sport airplane, N61SC, made a forced landing in a cornfield near Detroit Lakes Airport (DTL), Detroit Lakes, Minnesota. The pilot sustained minor injuries and the airplane sustained substantial damage. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident and no flight plan had been filed. The local fight had departed about 1815 and was returning to DTL at the time of the accident. The pilot stated to the responding Federal Aviation Administration (FAA) inspector that he was conducting a local flight to ensure the airplane was operating normally for his upcoming trip. While returning to the airport the engine suddenly experienced and loss of power and he was unable to maintain altitude. He could not reach the airport so he executed a forced landing to the corn field. After the airplane flipped inverted, he exited under his own power. The pilot added that he had installed a 260-horsepower Mercury marine-type outboard engine. This engine was too heavy for the airplane so he later installed a 200-horsepower Mercury marine-type outboard engine, which was water-cooled with a fabricated radiator and heat exchange system. The airplane came to rest inverted in a corn field about 1/4-mile northwest of DTL. About 50 ft of corn had been flattened leading up the accident site. Fuel residue was observed around the airplane's fuel tank and absorbent material had been placed on the ground by first responders to absorb the fuel spillage. In a post-accident statement, the pilot reported that he was about 1.5 miles north of runway 17 when he felt the airplane settle so he advanced the throttle, but the engine did not respond. He was unable to reach the runway so he completed a "falling leaf" maneuver to descend quickly. As the airplane approached the ground, he "broke the stall" and then settled into the corn stalks. The airplane continued forward about 150 ft, then nosed over and came to rest inverted. He added that the engine was new and had accumulated about 4.5 hours of ground run time with no anomalies. On July 29, 2019, the pilot reported to the NTSB that he had examined the engine and determined that one of the engine's electrical switch boxes had an open circuit and the open circuit did not allow and electrical charge to reach the Nos. 1, 3, and 5 spark plugs. The other switch box that allowed electrical charge to the other 3 cylinders had a closed circuit and operated normally.