On March 5, 2000, at 1406 central standard time, a Alon Ercoupe, N6560Q, was substantially damaged during a forced landing after a loss of engine power while on downwind after takeoff. The airplane landed in a bean field and nosed over. The commercial pilot and one passenger received minor injuries. The 14 CFR Part 91 pleasure flight had departed Osceola Municipal Airport, Osceola, Iowa, on a local flight. Visual meteorological conditions prevailed and no flight plan had been filed. The pilot reported there was about eight gallons of fuel in each of the wing tanks and about five gallons in the header tank. He reported everything appeared normal after he had conducted his preflight and the before takeoff checks. He reported, "At about 250-300 feet above ground level the engine ceased to make any power." The pilot was unable to restart the engine. The pilot elected to land in a bean field. The airplane nosed over in the field during landing rollout. Examination of the wreckage revealed the fuel line from the header tank to the gascolator was restricted prior to the reaching the firewall. The reason for the blockage was undetermined. No other anomalies with the airplane were found.