On August 12, 1993, at 1610 eastern daylight time, an R.D. Bell/Pietenpol Aircamper, N194BB, registered to Robert D. Bell of Rochester Hills, Michigan, and piloted by a private pilot, was substantially damaged when its main landing gear collapsed upon touchdown onto Runway 9 Left (3,250' X 75' dry asphalt) at the Pontiac/Oakland Airport, Pontiac, Michigan. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 flight had not filed a flight plan. The pilot reported no injuries. The flight originated from Lake City, Michigan, exact time unknown. According to the pilot's on NTSB Form 6120.1/2, the airplane performed a three point landing. He stated the airplane started to drift to the right during the initial phase of the landing roll. He said he applied left rudder to get the airplane back on the runway centerline. During the airplane's return to the runway's center, the right landing gear collapsed. The on-scene investigation was conducted by Federal Aviation Administration Principle Maintenance Inspector (PMI). The PMI confirmed the right main landing gear collapse. He stated he did not observed any fatigue generated cracking on the assembly. The PMI's statement is appended to this report. The PMI stated the airplane had been involved in two previous hard landing events on July 22, 1988, and August 20, 1988. The July 22, event resulted in a collapsed right main landing gear. The logbook did not specify if the landing gear had collapsed as a result of the hard landing on August 20, 1988. Copies of the airplane logbook are appended to this report.