On May 5, 2004, approximately 1105 mountain daylight time, an Engineering and Research (Ercoupe) 415G, N94405, owned and operated by the pilot, was destroyed when it impacted terrain near Falcon, Colorado. The private pilot and his passenger received minor injuries. Visual meteorological conditions prevailed, and no flight plan had been filed for the personal flight being conducted under Title 14 CFR Part 91. The flight originated approximately 1055. According to the pilot, he and his wife departed Meadow Lake Airport for a local flight. The airplane was at maximum gross weight. They encountered clear air turbulence. At full power of 2,250 rpm and an indicated airspeed of 75 mph, the airplane would not climb. He decided to turn around and return to the airport. After turning onto the downwind leg, the airplane encountered a "rotor wave" and the left wing dropped. The pilot applied full right aileron input with no effect. The airplane entered a spiral and impacted terrain. The left wing tip scraped the ground, spinning the airplane around. It became airborne again, then the right main landing gear struck a ditch. This collapsed the nose and right main landing gears. In addition, the right wing was sheared and the empennage was buckled.