Winsted, MN, USA
N63RK
HOFFMANN HK36R SUPER DIMONA
While on a visual approach to the runway, the pilot elected to perform a 360-degree turn at low altitude under idle engine power to allow for spacing between his airplane and an airplane near the runway. The passenger reported that, after completing the 360-turn, the pilot said something like "oh, oh," and then the pilot pitched the airplane's nose down, consistent with a recovery maneuver from an aerodynamic stall. The airplane impacted terrain short of the runway, and the passenger could not recall if the pilot applied engine power prior to the impact. The airplane's structure remained fairly intact, consistent with a low angle of impact. There was no evidence of any preimpact mechanical anomalies with the airplane.
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 sustained fatal injuries and the pilot-rated passenger sustained serious injuries. The motorglider was registered to Koair Corporation, Eden Prairie, Minnesota, and operated by the pilot. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 personal flight. The flight originated from Flying Cloud Airport (FCM), Minneapolis, Minnesota, at an unknown time. According to a telephone interview with the passenger, which was conducted by a Federal Aviation Administration (FAA) inspector, the purpose of the flight was familiarization for the passenger who was scheduled to conduct an instructional flight in the accident motorglider the following day. Unable to find adequate thermals during the flight, the pilot asked the passenger if he wanted to observe a landing prior to returning to FCM. They overflew 10D to verify the wind conditions, which were estimated to be less than 5 knots and appeared to favor runway 9, and entered a left downwind for runway 9. The pilot announced his intentions over the radio. A Cessna Caravan on the ground at 10D announced his intention to hold short of the runway, but was then observed by the pilot and passenger to back taxi on the runway. Approximately 1,000 feet above ground level, the passenger felt they had adequate altitude to continue the approach and glide in at idle engine power. As a result of the Cessna's back taxi, the pilot suggested a 360-degree turn. After completing the 360-degree turn, the passenger recalls the pilot saying something to the effect of "oh, oh" and the pilot then pitched the nose down. The passenger recalled being too close to the field, but not the impact with terrain. The passenger did not recall hearing the engine respond to any power inputs that may have been made by the pilot during the approach sequence. The Cessna Caravan pilot reported he made a radio call on 10D's common traffic advisory frequency (CTAF) with his intention of departing runway 27. Because the Cessna was on the only taxiway to the ramp, the Cessna pilot decided to execute a short back taxi to the far east side of the runway 9. At that time, the pilot noticed the motorglider was in a left hand circling pattern on base for runway 9. The Cessna pilot maneuvered his airplane around the south boundary line of the runway and performed a 180 degree turn to the left to look for the motorglider. The pilot noticed the motorglider just before it impacted the terrain. Based on his operating experience at 10D, the pilot thought the motorglider was low of a normal approach to the runway. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with airplane single-engine land, single-engine sea, multi-engine land, and instrument ratings. The pilot also held a private pilot certificate with a glider rating. The pilot's most recent third class medical certificate was issued on June 9, 2011. The pilot's logbook and flight time was not obtained; however, he reported 3,100 total hours and 30 hours in the previous six months on his most recent medical application. The passenger reported the pilot's total time was 3,142 hours, with approximately 650 hours in the accident motorglider. The passenger stated the pilot had no health issues prior to or during the flight. AIRCRAFT INFORMATION The Hoffman HK36R Super Dimona is a two-place powered glider constructed of composite materials. The glider is powered by a Rotax 912 engine and MT propeller. The standard airworthiness certificate was issued on June 23, 1994, and was registered to the owner June 24, 1994. The aircraft logbooks were not obtained; however, a family representative provided a receipt of an annual inspection that was completed on May 1, 2011. AIRPORT INFORMATION Runway 9/27 is a turf runway, which measures 3,248 feet in length by 200 feet in width, at an elevation of 1,030 feet mean sea level. The runway is designated with yellow cones. The runway features a hard surface taxiway to the ramp, which is located near the end of runway 9 (or the departure end of runway 27). The airport does not have a designated parallel taxiway to runway 9/27. WRECKAGE AND IMPACT INFORMATION A postaccident examination of the motorglider by a FAA inspector showed 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 came to rest approximately 10 feet behind the main wreckage. The instrument panel was partially separated from its fuselage structure and displaced to the right. PATHOLOGICAL INFORMATION On September 6, 2011, an autopsy was performed on the pilot by Hennepin County Medical Examiner's Office. The cause of death was listed as blunt force injuries. The Bioaeronautical Research Science Laboratory, FAA, Oklahoma City, Oklahoma, performed a postmortem toxicology of specimens from the pilot. The specimens were negative for carbon monoxide, cyanide, and ethanol. An unspecified amount of Etomidate and Glipizide were detected in the blood and urine. Additionally, 287 (mg/dl) Glucose was detected in the urine, and 7.2 percent Hemoglobin A1C was detected in the blood. TEST AND RESEARCH On November 10, 2011, the engine was examined by FAA inspectors. Examination of the engine showed mechanical continuity between the propeller, crankshaft, and camshaft. Thumb compression was noted on 3 of the 4 cylinders. The number 3 cylinder valves and piston showed continuity, but thumb compression could not be obtained. There was no evidence of a cylinder failure. The engine fuel lines were separated at the firewall, consistent with damage sustained during the impact. The fuel shut off switch operated and was found in the ON position. The carburetor float assemblies were clean and operated smoothly. Continuity to the carburetors and their cables was established.
The pilot did not maintain adequate airspeed while maneuvering at low altitude, which resulted in an aerodynamic stall.
Source: NTSB Aviation Accident Database
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