On July 2, 1996, about 1845 eastern daylight time, a Lake LA4-200, N51DG, was substantially damaged during landing at Lake Wentworth, Wolfeboro, New Hampshire. The private pilot, sole occupant, sustained minor injuries for the personal, local flight conducted under 14 CFR Part 91. Visual meteorological conditions prevailed and no flight plan was filed. According to the pilot, he departed Crystal Lake in Gilmanton, New Hampshire about 1830, destined for Laconia, New Hampshire. While en route he decided to do a touch-and-go landing on Lake Wentworth. The pilot reported: "The lake was calm. I entered downwind and went through the checklist, using the manufacturer's card. Then when turning base, I again went through the checklist by using the card. On final I did a visual again of landing gear, flaps, trim, prop, and mixture. I trimmed the plane for a glassy water landing, when I heard the keel touch the water with a nice sharp slicing sound, and then a loud roar. The next thing I knew I was looking up from the bottom of the lake. When I came up to the top of the water, the plane was in pieces. I was shortly picked up by 2 men and a woman in a boat." The pilot reported no mechanical malfunction. The FAA reported "the aircraft came to rest in fifty-seven feet of water. The nose of the aircraft was totally destroyed, and was held onto the main fuselage by hydraulic lines, and electrical wiring. The fuselage longerons were bent upwards. The tail of the aircraft was bent up and forward. There were several propeller cut marks in the leading edge of the vertical stabilizer, and the leading edge of theright horizontal stabilizer. The engine and pylon were still attached to the fuselage. With exception of minor leading edge damage to the right win, both wings were not damaged. The wing center section was not deformed laterally or horizontally." The FAA examination of the aircraft did not disclose evidence of mechanical malfunction.