On July 18, 1999, about 1300 Alaska daylight time, an unregistered Nix Avid Flyer experimental airplane sustained substantial damage during a forced landing after takeoff from the Birchwood Airport, Chugiak, Alaska. The solo student pilot was not injured. The airplane was owned and operated by the pilot. The flight was conducted under 14 CFR Part 91, as a local flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. According to an FAA inspector who interviewed the pilot at his home, the pilot said he placed the fuel and oil mixture in the airplane, and then took off from Birchwood. The pilot indicated that shortly after takeoff, the engine "seized." During the ensuing forced landing, the landing gear contacted a rut, and the airplane nosed down. The airplane sustained substantial damage to the landing gear mounting structure. The FAA inspector told the NTSB investigator-in-charge that he was able to rotate the propeller by hand, and that the engine felt normal. According to the FAA inspector, another pilot at the airport reported that he had told the accident pilot that the airplane was not legally airworthy and should not be flown. He also told the accident pilot that he should receive flight instruction before flying the airplane. The FAA inspector said the accident pilot was told that the engine was not reliable due to its age and lack of use. The witness pilot told the inspector that the accident pilot placed fuel in the airplane and took off. After about 30 minutes had elapsed, the witness pilot decided to look for the accident airplane and found it in the mud flats near the airport. The pilot submitted an incomplete NTSB Pilot/Operator report.