On September 25, 1999, at 1654 eastern daylight time, a Dominator homebuilt gyroplane, N4449N, was substantially damaged when it impacted terrain while maneuvering at the Auburn Municipal Airport, Auburn, Maine. The certificated private pilot was not injured, and visual meteorological conditions prevailed. A visual flight rules flight plan was not filed, and the personal local flight was conducted under 14 CFR Part 91. According to the pilot, he was practicing a 180 degree turn with 0 airspeed to a downwind condition at 100 feet agl when the accident happened. The pilot added that he had just successfully completed the maneuver once, and was attempting it for a second time. During the second attempt, the pilot slowed the gyroplane until reaching approximately 0 airspeed then applied pedal to execute the turn. After completing the turn, the gyroplane entered a rapid descent. The pilot advanced the throttle, and lowered the nose of the gyroplane to gain airspeed. Recognizing the impending impact, the pilot leveled the rotor's tip-path-plane, and the gyroplane impacted the ground level with forward airspeed. The landing gear collapsed, and the rotor contacted the ground on both sides. In addition, the rotor contacted the engine driven propeller, shearing off all three blades. The gyroplane bounced back into the air, and then impacted the ground for a second time. During the second impact, the gyroplane was level, but rolled right after ground contact, and slid 20 to 30 feet on its side before coming to a stop. The pilot reported the winds were approximately 10 knots. He made no mention of any preimpact failures or malfunctions that may have contributed to the accident. According to the manufacture of the kit, the gyroplane would develop a 1,000 to 1,500 foot per minute descent at 0 airspeed.