On April 13, 2006, about 1340 eastern daylight time, an amateur-built Lee SQ2000 airplane, N416, piloted by a private pilot, was substantially damaged during landing on runway 31 (3,030 feet by 75 feet, asphalt) at Andrews University Airpark (C20), Berrien Springs, Michigan. The personal flight was being conducted under 14 CFR Part 91 on a visual flight rules (VFR) flight plan. Visual meteorological conditions prevailed at the time. The pilot and passenger were not injured. The flight departed Forest City Municipal Airport (FXY), Forest City, Iowa, about 1200. The pilot reported that the airplane touched down on the runway during landing, and that "it appeared [to be] a good touchdown." He stated that during the rollout, the airplane felt "rubbery" and "vibrated or appeared to hop." He lost control of the airplane and it subsequently departed the right side of the runway. The pilot noted that the flight was "very turbulent," although it was "a little more manageable" at lower altitudes. The airport manager stated that the airplane came to rest adjacent to the airport's segmented circle. The airplane was located approximately 120 feet from the edge of the pavement and about 2/3 down the runway length from the displaced threshold. The airplane was oriented on a west heading; pointed toward the intersection of the runways. Both left and right main landing gear had collapsed. A pin on the right gear brace appeared to have failed. The brace on the left gear appeared to have failed. The airport manager reported that skid marks observed on the runway appeared to be associated with the right main landing gear of the accident airplane. He stated that the marks started approximately one-quarter of the way down runway 31, near the first taxiway intersection after the displaced threshold. He noted that the marks were intermittent. Each skid mark was about 18 inches long, with clear (non-skid) intervals of approximately 6 feet between them. In addition, the marks appeared to "jump back and forth" laterally from one mark to the next. They appeared to move from side to side about 6 - 8 inches between each mark. He added that the marks veered toward the right side of the runway, and stopped about 200 feet before the point at which the airplane left the pavement. Marks from the accident airplane continued in the grass area adjacent to the runway. Southwest Michigan Regional Airport (BEH) was located approximately 11 nautical miles north of C20. Winds recorded by the BEH Automated Surface Observing System (ASOS), at 1353, were from 230 degrees at 13 knots, gusting to 20 knots.