On June 24, 1994, at 1700 mountain daylight time, a Mustari Dragonfly Mark II, N3147B, piloted by the private pilot/owner, sustained substantial damage when it struck power lines while maneuvering after takeoff from the William B. Heilig Airport, in Scottsbluff, Nebraska. The pilot, the sole occupant, received serious injuries. Visual meteorological conditions prevailed for the flight, no flight plan was filed. The personal flight was originating from Scottsbluff, Nebraska, with an intended destination of Hastings, Nebraska. The pilot stated he flew to Scottsbluff to visit his mother in the hospital. He arrived about midday, and had the airplane topped off with 100LL fuel. It was about 1650 when the pilot attempted to depart the Scottsbluff airport. He stated: "Aircraft ascended to about 150 - 200 feet AGL and would no longer climb. Because of rising terrain I decided to turn back to the airport. I knew I would lose altitude on my turn...Once I got turned around I was looking at two sets of power lines...." The airplane struck the first set of power lines and came to rest in a soybean field. The pilot stated the airport elevation was 3,965 feet, the temperature was 92 degrees Fahrenheit, and density altitude had decreased the airplanes performance. He stated there was no mechanical malfunction, and indicated he could have prevented the accident "...by restricting my flights to lower elevation airports when temp. is above 90 [degrees]."