HISTORY OF FLIGHTOn September 16, 2012, approximately 0820 mountain daylight time, an experimental light sport KR2S airplane, N966G, registered to the pilot, was substantially damaged when it impacted the ground while maneuvering to land at the Pueblo Memorial Airport (PUB), Pueblo, Colorado. The sport pilot, who was the sole occupant, sustained fatal injuries. Visual meteorological conditions prevailed and a flight plan was not filed for the local flight. The flight was being conducted under the provisions of 14 Code of Federal Regulations Part 91. The flight originated about 0814 from PUB and was returning to land when the accident occurred. The airplane departed from runway 26L about 0814. Two minutes later, the pilot called PUB tower and requested to return to the airport for suspected carburetor icing. The tower controller acknowledged the call and told the pilot to enter a left base for runway 26L. The controller also asked the pilot if he needed any assistance, and the pilot replied that he did not. He was then cleared to land the airplane on runway 26L. The controller observed that the airplane was approaching the airport "fast" and appeared to attempt a go-around maneuver. The airplane then made a hard turn to the right as if it was trying to land on runway 8L. The controller estimated that the airplane was about 200 feet AGL in the right turn. The airplane appeared to stall and descended toward the ground in a nose low, right wing down attitude. It impacted a grass covered near the northwest corner of where runway 26R and runway 17 intersect. PERSONNEL INFORMATIONThe pilot held three FAA issued certificates; Private Pilot Single Engine Land, Sport Pilot, and Repairman Experimental Aircraft Builder. According to FAA records, the pilot's most recent medical exam was dated December 7, 2001. On the date of the 2001 medical exam the pilot was issued a Class III medical certificate. The notes section of the certificate stated that the pilot shall possess glasses for near/intermediate vision. The pilots reported flight time during the 2001 exam was 1,500 hours. Pilot log books were not available during the investigation to verify additional hours since the 2001 medical exam. In discussions with the pilot's associates, it is estimated that the pilot had about 2,000 hours of flight time at the time of the accident, 200 of which were in the accident airplane. AIRCRAFT INFORMATIONThe airplane, model KR2S experimental homebuilt, was manufactured by the pilot. FAA records indicate that construction of the airplane began in October of 2004. The airplane was issued its Experimental Homebuilt airworthiness certificate on May 5, 2007. The airplane was equipped with a Lycoming O-235-C2 engine. Airframe and engine logbooks were not available during the investigation. In discussions with the pilot's associates, it is estimated that the total airframe and engine times at the time of the accident was about 200 hours. An associate of the pilot reported that the airplane's original Lycoming O-235-C2 engine had recently been replaced by a Lycoming O-320-A2B engine. The associate also reported that the accident flight may have been the first or second flight with the new engine installation. METEOROLOGICAL INFORMATIONThe observed weather at Pueblo Airport at the time of the accident was clear skies, 10 miles visibility, and wind from 260 degrees at 7 knots. Temperature 12 degrees Celsius. Dew Point 4 degrees Celsius. AIRPORT INFORMATIONThe airplane, model KR2S experimental homebuilt, was manufactured by the pilot. FAA records indicate that construction of the airplane began in October of 2004. The airplane was issued its Experimental Homebuilt airworthiness certificate on May 5, 2007. The airplane was equipped with a Lycoming O-235-C2 engine. Airframe and engine logbooks were not available during the investigation. In discussions with the pilot's associates, it is estimated that the total airframe and engine times at the time of the accident was about 200 hours. An associate of the pilot reported that the airplane's original Lycoming O-235-C2 engine had recently been replaced by a Lycoming O-320-A2B engine. The associate also reported that the accident flight may have been the first or second flight with the new engine installation. WRECKAGE AND IMPACT INFORMATIONThe NTSB did not travel to the accident site on the date of the accident. The airplane wreckage and engine was moved from the runway environment and retained for examination in a secured hangar located on the Pueblo Airport. The examination was conducted on September 20, 2012. All structural and flight control components were identified, and there was no evidence of pre-impact failures. Although the wood and fabric fuselage was mostly destroyed from impact forces, control cable continuity was confirmed from the cockpit to all flight control surfaces. All of the breaks throughout the control system displayed overload features consistent with impact forces. The engine remained attached to the firewall and the wooden propeller hub was attached to the crankshaft. Both propeller blades were fractured and splintered just outboard of the hub. The fractures and splintering were consistent with the engine operating at impact. The engine was separated from the firewall and secured to a chain on a forklift for examination. The oil sump and carburetor float bowl were found separated from impact forces and the rear accessory case was fractured. The valve covers and upper spark plugs were removed. The spark plugs displayed normal wear with slight carbon deposits on the electrodes. In lieu of magnetos, a Light Speed Engineering ignition system was installed on the engine. The cylinders were inspected utilizing a bore scope and no anomalies were found – the inside of the cylinders appeared clean and void of deposits. They appeared properly ported and polished. The crankshaft was rotated by hand and thumb compression was established to all cylinders. When rotated, internal drive train continuity was established throughout the crankshaft to the accessory case. No pre-impact anomalies with the engine were discovered. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy of the pilot was performed by a forensic pathology consultant on September 17, 2012. The autopsy concluded that the cause of death was multiple blunt force injuries and the report listed the specific injuries. The FAA's Civil Aerospace Medical Institute (CAMI), Oklahoma City, Oklahoma, performed toxicological tests on specimens that were collected during the autopsy (CAMI Reference #201200198001). Tests for carbon monoxide and cyanide were negative. Results were positive for the following volatiles and drugs. Cetirizine detected in blood (cavity), liver, and urine. Citalopram detected in blood (cavity - 0.108 ug/ml, ug/g), liver, and urine. Diphenhydramine detected in blood (cavity – 0.028 ug/ml, ug/g), and urine. Ibuprofen detected in urine. Metoprolol detected in blood (cavity, and liver. N-Desmethylcitalopram detected in blood (cavity), and liver Tamsulosin detected in blood (cavity), and liver TESTS AND RESEARCH Since the pilot reported that he suspected carburetor icing prior to returning to land, carburetor icing probability chart information was reviewed corresponding to the reported weather conditions at the time of the accident flight. According to the chart, the airplane was operated within the range (Temperature 12 degrees Celsius and Dew Point 4 degrees Celsius) of "serious" carburetor icing at any power setting. The airplane was equipped with a carburetor heating system, however, due to impact forces, it could not be determined whether the system was turned on or functioning at the time of the accident. ADDITIONAL INFORMATION The wreckage was released to the owner's representative.