On May 2, 2010, about 1713 central daylight time, an unregistered CGS Hawk ultra-light airplane was substantially damaged after impacting terrain near Haysville, Kansas. The private pilot was fatally injured. The local flight originated at Selby Farm Airport (35KS), Derby, Kansas and was being conducted under the provisions of 14 Code of Federal Regulations Part 91 without a flight plan. Visual meteorological conditions prevailed at the time of the accident. Witnesses observed the airplane depart 35KS to the south and turn to the west. One witness estimated the aircraft reached 300 to 400 feet above the ground. Witnesses described hearing the engine power decrease, while the aircraft pitch increased as the altitude remained about the same. They observed the aircraft turn to the north and then it appeared to stall and spin into the ground. The engine power was described as increasing as the aircraft spun. The pilot, age 78, held a private pilot certificate with ratings for airplane single engine land and glider aero tow. His last application for a third class medical certificate was dated September 3, 2009, on which he reported 828 total flight hours and 20 flight hours in the previous six months. The pilot’s logbooks were not located during the investigation. The pilot’s medical records indicated a history of pulmonary embolism. An autopsy of the pilot was conducted by the Regional Forensic Science Center, Sedgwick, Kansas. The cause of death was attributed to multiple blunt force injuries. Post-accident examination of the aircraft by Federal Aviation Inspectors revealed both left and right wings were twisted, struts were bent, and the fabric wing covering was torn. One of the wooden propeller blades was splintered with about one quarter of the blade outboard of the hub remaining. The second blade was mostly intact with about three quarters of the blade remaining and the end splintered. Flight control continuity was verified from all control surfaces to the cockpit controls. Throttle cable continuity was verified from the throttle control to the carburetor. The carburetor responded normally to throttle cable movements. Fuel was found in the carburetor bowl and the fuel filter was found free of contaminants. About one gallon of fuel was found in the fuel tank. No moisture was noted in the fuel. The aircraft was powered by a Rotax 503 engine. No engine anomalies were observed.