On August 22, 2001, about 1200 Alaska daylight time, an experimental Thomson Avid Flyer, N47065, received substantial damage following a loss of engine power and subsequent forced landing near the Birchwood Airport, Chugiak, Alaska. The solo private pilot/owner was not injured. The local 14 CFR Part 91 flight operated in visual meteorological conditions. In a written statement to the NTSB dated August 27, the pilot related he had departed from runway 19L at the Birchwood Airport, and had climbed to approximately 800 feet msl in the ultralight pattern, when the engine starting missing and then quit. He wrote he was about 1/2 mile from the end of the runway, but was unable to glide that distance, and elected to land on the only flat spot available near adjacent railroad tracks. He said the airplane bounced once on landing, and then collided with a ditch, collapsing the main landing gear. The pilot said the loss of engine power was due to a broken spark plug on one of the two engine cylinders. Postaccident inspection of the airplane by an FAA inspector from the Anchorage Flight Standards District Office, disclosed substantial damage to the fuselage tubing structure near the main landing gear.