On July 16, 2002, approximately 1000 eastern daylight time, a Piper PA-11S, a floatplane, N4504M, was substantially damaged during a high speed taxi on Sheepscot Lake, Palermo, Maine. The certificated private pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. A Federal Aviation Administration (FAA) inspector interviewed the pilot. According to the inspector, the pilot had just replaced an adjustable oil pressure relief valve on the engine. He then flew to Sheepscot Lake to test and monitor the oil pressure gauge. During a high speed taxi test toward the northeast, the pilot said the wind lifted the left wing and dropped the right wing into the water, which caused the aircraft to nose over. The front spreader bar on the floats broke, and the propeller struck the right float and it filled with water. The FAA inspector performed an on-scene examination of the airplane. According to the inspector, the left float had separated from the airplane, but the right float exhibited more impact damage. The propeller was also damaged. The pilot reported a total of 4,000 flight hours, of which, 400 hours were in make and model. The pilot also reported that there were no mechanical deficiencies. Weather reported at Augusta State Airport (AUG), 15 nautical miles southwest, at 0953, included wind from 350 degrees at 10 knots, visibility 10 statute miles, few clouds at 9,500 feet, temperature 68 degrees F, and dewpoint 54 degrees F.