HISTORY OF FLIGHTOn September 13, 2020, about 1100 central daylight time, an American Champion 8KCAB, N83DH, was substantially damaged when it was involved in an accident near Groton, South Dakota. The commercial pilot and passenger sustained fatal injuries. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. According to a witness, after takeoff, the airplane accelerated down the runway in ground effect before the nose pitched up to an estimated 45° angle. The airplane then rolled right and inverted and exited the roll maneuver in a nose-low attitude before impacting the ground. One witness estimated that the roll was initiated between 75 and 100 ft above ground level (agl). Two witnesses reported that the maneuver appeared intentional due to the rapid roll rate. Of three witnesses interviewed, all stated that they did not know of any planned aerobatic maneuvers for the flight. The flight took place as part of a fundraising event sponsored by a group of pilots attempting to raise money to encourage youth interest in aviation. A family member stated that the pilot routinely performed low-level aerobatics in the accident airplane. There were no aerobatic waivers issued for the accident flight or for the fly-in event. WRECKAGE AND IMPACT INFORMATIONThe airplane came to rest about 200 yards south of runway 15. The airplane impacted in an upright, nose-low attitude before coming to rest inverted. Both wings, the fuselage, and empennage all sustained substantial damage. Flight control continuity was established from the cockpit controls to the ailerons, rudder, and elevator. Internal continuity of the engine was established. The propeller blades were sheared flush at the hub. A witness on the ground stated that the engine sounded “healthy” and he did not hear any interruption in power before impact. The postaccident examination revealed no mechanical malfunctions or anomalies that would have precluded normal operation.