On July 13, 1999, at 1203 central daylight time, an amateur-built Grimm Sea Hawker, N188AK, piloted by an airline transport pilot, was destroyed when it was consumed by fire following an impact with terrain, during an emergency landing, near the Princeton Municipal Airport (PNM), Princeton, MN. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 flight was not operating on a flight plan. The pilot, who was the sole occupant, received serious injuries. The flight had originated about 1200 for a local flight. In a written statement, the pilot said that after takeoff from runway 15 (3,900 feet by 75 feet, dry asphalt), at PNM, at an altitude of about 300 feet above ground level (AGL), and an airspeed of 70 knots, "...the aircraft began to roll around it's longitudinal axis left then right continuously." The pilot said that, "the uncontrollable roll left/right started a descent of the aircraft." The pilot was attempting to return to PNM when he determined that the aircraft was "... too low for landing at PNM and an emergency landing was made...." The pilot said that the left wing of the airplane struck a tree on landing and subsequently burst into flames as he was attempting to exit the aircraft. The aircraft was a kit-built amphibian consisting of a composite airframe structure and was powered by a Lycoming O-320 series engine. The aircraft came to rest, in a vacant lot, approximately 0.5 miles north of the approach end of the runway at PNM. A postaccident examination revealed no identified anomalies with respect to the airframe or control system. The entire fuselage and the inboard portions of the wings were consumed by fire. The engine was examined and it evidenced fire damage.