On November 3, 2001, about 1500 eastern standard time, a Maule M7-260, N5511G, was substantially damaged while landing on a private lake in North Lima, Ohio. The certificated private pilot was not injured. Visual meteorological conditions prevailed and no flight plan had been filed for the local personal flight conducted under 14 CFR Part 91. The pilot owned the "amphibian" airplane, which was equipped with both floats and a retractable wheel landing gear configuration. In a written statement, the pilot said he performed two runway landings at the Youngstown Elser Metro Airport (4G4), Youngstown, Ohio, and then returned to land on his private lake located about 2 miles north of 4G4. The pilot said he inadvertently landed on the lake with the landing gear wheels in the extended position and the airplane flipped over. He further said he did not experience any mechanical problems with the airplane. The pilot reported 562 hours of total flight experience, with 300 hours in make and model.