On May 17, 2014, about 1345 central daylight time, an experimental amateur-built Crawford Preceptor Ultra Pup airplane, N1171Q, impacted trees and terrain after experiencing a loss of engine power near Mabel, Minnesota. The pilot, sole occupant, received minor injuries and the airplane was substantially damaged. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the ferry flight, which operated without a flight plan. The flight originated from the Houston County Airport (KCHU), Caledonia, Minnesota.The pilot, who had recently purchased the airplane, reported that the cross-country flight started from Alexander Field South Wood County Airport (KISW), Wisconsin Rapids, Wisconsin, with full fuel tanks. The pilot added that during the first leg of the flight he experienced what he thought was carburetor icing 2-3 times. During those occasions, the engine ran rough and the rpm would decrease from 3,200 to 2,800. After 20-30 seconds of applying carburetor heat the engine appeared to recover.
The pilot stopped at CHU to refuel and added 9.9 gallons of 100 low lead aviation gasoline before continuing his flight home. About 12 miles from CHU, the pilot felt a vibration or flutter from the engine and elected to return to CHU. He applied carburetor heat; however, the engine lost power and the airplane collided with trees in a wooded area.
An examination of the airplane revealed substantial damage to the fuselage and both left and right wings. A visual inspection of the engine did not reveal a reason for the loss of power. Additionally, fuel was available in the airplane and free of contaminants.
At 0854, the automated weather station at KISW recorded wind from 280 degrees at 9 knots, temperature 51 degrees Fahrenheit, dew point 31 degrees Fahrenheit, visibility 10 miles, a clear sky, and an altimeter setting of 30.05 inches of Mercury. At 1054, the station recorded a temperature of 57 degrees Fahrenheit and a dew point of 25 degrees Fahrenheit.
At 1053, the automated weather station at La Crosse, Wisconsin (KLSE), located about 20 miles northeast of KCHU recorded wind from 250 degrees at 7 knots, temperature 59 degrees Fahrenheit, dew point 30 degrees Fahrenheit, visibility 10 miles, scattered clouds at 8,500 feet and an altimeter setting of 30.07 inches of Mercury. At 1354, the station recorded a temperature of 63 degrees Fahrenheit and a dew point of 27 degrees Fahrenheit.
The carburetor icing probability chart included in Federal Aviation Administration Special Airworthiness Information Bulletin No. CE-09-35, Carburetor Icing Prevention, indicated that the airplane was operating in an area that was associated with a serious risk of carburetor ice accumulation at glide power settings and a risk for light carburetor icing at cruise power.