On December 2, 1999, at 1045 central standard time (All times CST), a Cessna A185F, N1756R, piloted by an airline transport pilot, was destroyed during a water landing on Branched Oak Lake near Raymond, Nebraska. The personal flight was operating under 14 CFR Part 91. Visual Meteorological Conditions prevailed during the flight. No flight plan was on file. The pilot and passenger reported no injuries. The flight originated as a local flight from Lincoln Municipal Airport, near Lincoln, Nebraska, at 1027. In his written statement, the pilot stated that he had performed some maintenance on the airplane and decided to perform a local test flight. He said that he recalled telling an air traffic controller that he had no intentions of landing on the water. As he got closer to the lake, he said, "With the past maintenance work, Lake completely abandoned and good water conditions I elected to land at the lake and double check floats for leaking, Hydraulic leaking and inspect cyl for any possible oil leaks that could be occuring." The pilot stated that he observed the shoreline through the right window to offset the glassy water conditions. He said, "The touch down was smooth but after a short run as I started to reduce power the plane yawed sharply to the right followed by a feeling like of the right float being pulled out from under the ship and with in a split second I felt the right wing go down and the nose was slamed into the water with the window being broken out and a real shot of water entered the cabin." The pilot said that he did not recall the airplane being cartwheeled. He said, "I truely feel that I might have hit something in the water. It seems that should be impossible in a lake like this but I feel that if there is damage to the right float then I am sure that the sharp Yaw to the right should be related to that damage. If the right float shows no damage then I would use an educated guess that Pilot error should be considered." At 1054, the Lincoln Municipal Airport, Lincoln, Nebraska weather was: Wind 220 degrees at 4 knots; visibility 4 statute miles; present weather mist; sky condition scattered 2,100 feet; temperature 9 degrees C; dew point 7 degrees C; altimeter 29.75 inches of mercury. The passenger said, "The weather conditions throughout the flight were calm, dry and hazy. The visibility was good enough that I was able to see across the entire lake and there was no wind blowing as we landed or when we were waiting for help to arrive." A review of the pilot's logbook revealed .2 hours of flight time in the accident type aircraft in the last 90 days. The logbook did not list any water landings within the last 90 days. A Federal Aviation Administration inspector performed an on-scene examination. The inspector said, "An on scene investigation of the aircraft and crash site did not indicate any pre-impact damage to the aircraft or amphibian floats." The float's landing gear was found retracted.