While maneuvering the gyroplane at a low altitude, the pilot inadvertently moved the engine throttle to idle. The pilot initially thought his engine had lost power and proceeded to set up for a forced landing. During the attempted forced landing, the pilot instinctively applied engine power to soften the landing, and the engine responded appropriately. The right main landing gear contacted the terrain, and the gyroplane rolled over. The gyroplane sustained substantial damage to the fuselage and vertical stabilizer. The pilot stated there were no mechanical issues or anomalies noted with the gyroplane. Postaccident examination of the airplane revealed no mechanical anomalies that would have precluded normal operation.