On June 12, 1997, at 1750 eastern daylight time, N1105H, an Aeronca S15AC floatplane, was substantially damaged when it collided with trees during taxi on a lake near Laconia, New Hampshire. The commercial pilot, the sole occupant was not injured. Visual meteorological conditions prevailed and a flight plan was not filed. The local, personal flight was conducted under 14 CFR Part 91. According to a Federal Aviation Administration (FAA) Inspector, the pilot reported that while taxiing the airplane downwind, "on the step" position, a gust of wind caught the left wing, and the airplane became airborne prematurely. The airplane struck trees, and came to rest in a marsh adjacent to the lake. The FAA Inspector said, the pilot was completing his run-up check which included an engine magneto check. The pilot said the airspeed was close to lift off speed, and the wind shifted during the run-up. The reported winds at the time of the accident were from 330 degrees at 11 knots, with gusts to 15 knots. The pilot reported that there was no mechanical malfunction with the airplane or engine. Examination of the wreckage revealed that the water rudder was found in the down position. Several attempts were made to contact the pilot both by telephone, and by mail. He did not return the pilot/operator report that was mailed to him.