On June 29, 1997, at 1536 eastern daylight time, an amateur built, Nieuport 12, N169RD, was destroyed during impact with trees and the terrain after takeoff from a private sod strip near Byron, Michigan. The private pilot received serious injuries. Witnesses stated that the engine suffered a loss of power during climb and they observed the airplane turning as though to return to the airport. The personal 14 CFR Part 91 flight was operating in visual meteorological conditions. No flight plan was on file. The local flight was originating at the time of the accident. The pilot stated that this was to be the first flight after a repair of the engine. He said that several "mud-wasp" nests were removed from various portions of the airplane which has accumulated while the airplane was inactive. He said that on initial climb the engine began to lose power. He said that there were a row of trees 300 feet from the departure end of the runway. The airplane initially cleared the trees, but in the pilots words "the plane stall-spun into a swamp." Subsequent examination of the accident airplane revealed contamination in the filter for the left carburetor, which the pilot indicated in all likelihood came from an insect nest which was not cleared from the fuel line which was open to the elements while the airplane was inactive.