On August 23, 2003, about 1230 eastern daylight time, a Cessna A185F, N44222, was substantially damaged while landing at Marion Municipal Airport (MNN), Marion, Ohio. The certificated private pilot and three passengers were not injured. Visual meteorological conditions prevailed for the flight that originated from Toledo Express Airport (TOL), Toledo, Ohio. No flight plan was filed for the personal flight conducted under 14 CFR Part 91. The pilot stated that he touched down on runway 07 at MNN. Shortly after touchdown, the airplane began to swerve left, and the pilot heard a scraping sound. The right main landing gear collapsed, the right wing contacted the runway, and the airplane came to rest on the runway. Examination of the airplane by a Federal Aviation Administration inspector revealed damage to the propeller, right wing, right main landing gear, and fuselage. The lower outboard portion of the right main landing gear leg was forwarded to the Safety Board's Materials Laboratory. Further examination of the component revealed that the fracture occurred through the upper bolt hole attachment. The forward portion of the bolt hole exhibited three fatigue regions originating from corrosion pits. The aft portion of the bolt hole exhibited one fatigue region originating from a corrosion pit. The pilot further stated that the airplane had accumulated approximately 8,000 total hours of operation. The airplane had accumulated 56 hours of operation since the last annual inspection, which was completed on March 14, 2003. Prior to the pilot's purchase of the airplane, it was operated as a "bush plane" in Guatemala. The pilot reported a total flight experience of approximately 766 hours; of which, 136 hours were in the same make and model as the accident airplane. The reported wind at the accident site, at 1253, was from 050 degrees at 6 knots.