On May 17, 2012, about 1150 mountain daylight time, an experimental Marley Kolb Firestarter II airplane, N9173T, impacted the ground in an open field about 100 yards north of the Cedar Valley Airport (UT10), Cedar Fort, Utah. The sport pilot/owner, the sole occupant, operated the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91 as a personal flight. The pilot received serious injuries; the airplane came to rest inverted and was substantially damaged. Visual meteorological conditions prevailed for the flight, and no flight plan was filed. The flight departed from an unknown location. A witness reported that she observed the airplane start to wobble during its landing sequence. She stated it was a windy day and that a sudden gust of wind caused the airplane to tip on its side while in the air. It appeared that the pilot attempted to level off the airplane but was unsuccessful. The airplane subsequently impacted the open terrain near the runway and rolled several times before coming to rest inverted. The Federal Aviation Administration (FAA) inspector who responded to the accident site was able to establish flight control continuity. He reported local thunderstorms with microburst in the area. The pilot did not provide a completed NTSB Pilot/Operator Aircraft Accident Report Form 6120.1 nor a written statement to the investigator.