On June 1, 2021, about 1900 central daylight time, an experimental, amateur-built Quad City Challenger II airplane, N3821P, was substantially damaged when it was involved in an accident near Wallingford, Iowa. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Responding Federal Aviation Administration inspectors reported that the pilot attempted to depart a residential driveway when it collided with a tree, descended, and impacted terrain. The airplane sustained substantial damage to the fuselage. The pilot did not hold a pilot certificate. He had recently replaced the engine and propeller and was not a certificated mechanic. The pilot had logged a few hours with the engine and propeller combination before the accident flight. Following the initial contact with the FAA, the pilot refused to cooperate more with the investigation and a follow-up engine examination could not be conducted.