On December 13, 2012, about 1530 central standard time, an experimental amateur-built Rotorway DB-1 helicopter, N828X, operated by a private individual, was substantially damaged when it impacted the ground following a loss of control while hover-taxiing at Carey Airport (TN56), Mayland, Tennessee. The private pilot received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight. The personal flight was conducted under the provisions of 14 Code of Federal Regulations (CFR) Part 91. According to the pilot, while hover-taxiing, about 3 feet above ground level, the engine suddenly accelerated and the helicopter started to gyrate violently. He attempted to maintain control of the helicopter when it began to drift to the left where his truck and trailer where parked. To avoid a collision with the truck, he raised the collective to climb over it. Once clear of the truck, the pilot lowered the collective and landed on a downward slope. The helicopter impacted the ground with the right skid, and rolled over on its left side, which resulted in the main rotor blades striking the ground. The main and tail rotor blades were substantially damaged; the empennage was dented and twisted; the left rear landing gear fractured; and the passenger side skid was bent. According to Federal Aviation Administration (FAA) records, the pilot held a private pilot certificate, with a rating for a rotorcraft-helicopter. The pilot’s most recent FAA third-class medical certificate was issued on May 12, 2011. The pilot reported 129 total hours of flight experience; of which, 29 hours were in the same make and model as the accident helicopter. The single-engine, single-rotor, kit helicopter was powered by a Rotorway, RW152, 150-horsepower engine. The helicopter was registered to the owner/operator and operated under personal use. A Special Airworthiness Certificate was issued on February 20, 1994. A Condition Inspection was completed in July 1, 2012. The owner installed a Blue Streak governor on March 8, 2010 and logged a total of 0.5 hour from the time of installation to the time of the accident. An FAA inspector looked at the governor parts and how they were connected on site without benefit of the instructions but after reading the instructions the governor appeared to have been installed correctly. Limitation 19 of the Operating Limitations attached to the Special Airworthiness Certificate required coordination with the Flight Standards District Office (FSDO) after incorporating a major change as described in 14 CFR 21.93. The owner was required to notify the FSDO of the location of the proposed test area and obtain concurrence from the FSDO as to the suitability of the proposed test area. The aircraft must remain in flight test for a minimum of 5 hours or for the time the FSDO assigned. Following satisfactory completion of the required number of flight hours in the flight test area, the pilot must certify in the records that the aircraft had been shown to comply with 91.319 (b). An FAA inspector could not find any record that the pilot complied with Limitation 19 of the Operating Limitations, nor did she find any documentation in the aircraft records that the test flights were completed. The pilot attended Rotorway Transition Training in October 2012 and received 4.8 hours of dual instruction. The training did not cover governor failures since that was considered an aftermarket install. The 1553 weather observation at Crossville Memorial-Whitson Field (CSV), Crossville, Tennessee, included wind calm, 10 statute miles visibility, sky condition clear, temperature 11 degrees C, dew point minus 11 degrees C, and an altimeter setting of 30.28 inches of mercury.