On October 26, 2008, approximately 1425 central daylight time, a Cessna 180K, N1846Z, registered to and piloted by an airline transport certificated pilot, was substantially damaged when the airplane nosed over and impacted terrain during landing at Clark Airport (3T6), Justin, Texas. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91 without a flight plan. The pilot, the sole occupant on board, was not injured. The local flight originated at an undetermined time. In his accident report the pilot wrote, "Upon landing, the nose of the airplane pitched down, making the airplane uncontrollable and [it] tipped on its back." The pilot also wrote that he didn't know why the airplane pitched down. He told an FAA inspector that he just "lost it." FAA post-accident inspection revealed no anomalies.