History of Flight
On September 5, 2011, at 1514 central daylight time, a Hoffman HK36R Super Dimona motorglider impacted terrain while maneuvering near Winsted Municipal Airport (10D), Winsted, Minnesota. The commercial pilot and a pilot-rated passenger were aboard. The flight, a personal flight under 14 Code of Federal Regulations Part 91, departed from Flying Cloud Airport (FCM), Minneapolis, Minnesota, at an unknown time. Visual meteorological conditions prevailed, and no flight plan was filed.
The passenger later stated the flight's purpose was familiarization for his scheduled instructional flight in the same aircraft the following day. Unable to find adequate thermals, the pilot asked if the passenger wanted to observe a landing before returning to FCM. They overflew 10D to check wind conditions, estimated at less than 5 knots favoring runway 9, and entered a left downwind for runway 9. The pilot announced his intentions by radio. A Cessna Caravan on the ground announced it would hold short but then was observed to back taxi on the runway. Approximately 1,000 feet above ground level, the passenger felt they had sufficient altitude to continue the approach at idle power. Due to the Cessna's back taxi, the pilot suggested a 360-degree turn. After completing the turn, the passenger recalled the pilot saying something like "oh, oh" and then pitching the nose down. The passenger remembered being too close to the field but not the impact. He did not recall hearing the engine respond to any power inputs.
The Cessna pilot reported he made a radio call to depart on runway 27. Because the only taxiway led to the ramp, he decided to back taxi to the far east side of runway 9. He noticed the motorglider in a left circling pattern on base for runway 9. He maneuvered his airplane around the south boundary and performed a 180-degree left turn to look for the motorglider, noticing it just before impact. Based on his experience, he thought the motorglider was low of a normal approach.
Personnel Information
The pilot held a commercial pilot certificate with airplane single-engine land, single-engine sea, multi-engine land, and instrument ratings, as well as a private pilot certificate with a glider rating. His most recent third-class medical certificate was issued on June 9, 2011. Although his logbook was not obtained, he reported 3,100 total hours and 30 hours in the previous six months on his medical application. The passenger reported the pilot's total time as 3,142 hours, with approximately 650 hours in the accident motorglider. The passenger stated the pilot had no health issues before or during the flight.
Aircraft Information
The Hoffman HK36R Super Dimona is a two-place, composite-construction powered glider, equipped with a Rotax 912 engine and an MT propeller. It received a standard airworthiness certificate on June 23, 1994, and was registered to Koair Corporation of Eden Prairie, Minnesota, on June 24, 1994. Although the aircraft logbooks were not obtained, a receipt for an annual inspection completed on May 1, 2011, was provided by a family representative.
Airport Information
Winsted Municipal Airport (10D) has a single turf runway, 9/27, measuring 3,248 feet by 200 feet at an elevation of 1,030 feet mean sea level. The runway is marked with yellow cones. A hard surface taxiway connects to the ramp near the approach end of runway 9 (departure end of runway 27). There is no designated parallel taxiway.
Wreckage and Impact Information
A postaccident examination by an FAA inspector revealed flight control continuity to the flight spoilers and ailerons. The empennage was damaged, and the elevator was separated. The main landing gear was separated and found about 10 feet behind the main wreckage. The instrument panel was partially separated from its fuselage structure and displaced to the right.
Pathological Information
An autopsy performed on September 6, 2011, by the Hennepin County Medical Examiner's Office listed the cause of death as blunt force injuries. Postmortem toxicology by the FAA's Bioaeronautical Research Science Laboratory was negative for carbon monoxide, cyanide, and ethanol. Etomidate and Glipizide were detected in the blood and urine, with unspecified amounts. Additionally, 287 mg/dl glucose was found in the urine, and 7.2 percent hemoglobin A1C was present in the blood.
Tests and Research
On November 10, 2011, FAA inspectors examined the engine. They found mechanical continuity between the propeller, crankshaft, and camshaft. Thumb compression was noted on three of four cylinders; the number 3 cylinder showed continuity but no thumb compression. No evidence of cylinder failure was observed. The engine fuel lines were separated at the firewall, consistent with impact damage. The fuel shutoff switch was found in the ON position. The carburetor float assemblies were clean and operated smoothly, and continuity to the carburetors and their cables was established.