On March 5, 1994, about 0845 eastern standard time, a homebuilt Harper Mustang II, N20768, registered to Jack W. Harper, was substantially damaged during the landing roll at the Cannon Creek Airport, Lake City, Florida, while on a 14 CFR Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The private-rated pilot was not injured and the pilot-rated passenger sustained minor injuries. The flight originated from the Herlong Airport, Jacksonville, Florida, about 45 minutes earlier. The pilot and pilot-rated passenger both stated that the approach to land was normal and the wind was directly down the runway. At touchdown, the airplane's left wheel landed first, then the right wheel touched down about 8 to 10 feet later. The right wheel assembly separated, and the airplane nosed over. The airplane came to rest inverted about 175 feet further along the runway. The pilot stated that the nuts which secure the wheel to the landing gear were not located. The threads of the bolts were stripped.