On September 4, 1995, at 1325 eastern daylight time, a Gillet, a homebuilt airplane, N4171G, was destroyed when it struck the water 3/4 mile south of the Robert Moses State Park, Fire Island, New York. The private pilot/owner of the airplane was fatally injured, and a second pilot was seriously injured. Visual meteorological conditions prevailed, for the personal flight that departed the Republic Airport, Farmingdale, New York, about 1300. No flight plan had been filed for the flight conducted under 14 CFR Part 91. During a telephone interview, the pilot's wife stated that the pilot departed home, about 0930. The pilot's plan had been to fly to Groton, Connecticut. A friend of the second pilot reported that he owned a Pitts S-2, and he performed aerobatic maneuvers in that airplane. The friend dropped the second pilot off at the Republic Airport that morning, and then drove out to the Robert Moses State Park, and observed him perform aerobatics over the water. When the friend returned to the airport to pick him up, she found a note which stated that he went flying with another pilot. According to witnesses in a boat, they observed N4171G during the last 300 feet of a descending spin and impact with the water. One witness stated: I looked up and saw a small white airplane at low altitude (maybe 200 feet) in a spin heading downward, at a slight angle toward the water. Within 10 to 15 seconds, the plane crashed about 300 feet from where my boat was. I didn't see any smoke or fire. An examination of the wreckage was conducted on September 7, 1995, under the supervision of a Federal Aviation Administration Inspector. The examination revealed no pre-impact failures of the airplane or engine. Control continuity was confirmed to the pilot's flight controls from the airplane's ailerons, rudder, and elevator. The airplane was constructed by the owner, and issued an FAA Airworthiness Certificate on March 20, 1994. The airplane kit manufacture's specifications described the airplane to be "fully aerobatic." The pilot/owner had accumulated over 500 hours of total pilot experience, of which about 239 hours were in this airplane. He was not known to have performed aerobatic maneuvers. The second pilot held a Private Pilot Certificate. He was reported to have about 1,750 hours of total pilot experience, 280 hours in the Pitts S-2, and about 1 hour in this make and model.