On September 6, 2002, at 1430 eastern daylight time, a homebuilt Glassair, N7223R, was substantially damaged during an engine start at Minuteman Airfield (6B6), Stow, Massachusetts. The certificated private pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local personal flight that was to be conducted under 14 CFR Part 91. According to the pilot, he set the vernier-type throttle to "a little more than 1/4-inch open," and started the airplane. He then attempted to reduce the power by twisting the throttle counter-clockwise. However, he was unable to retard the throttle to the idle position. The brakes could no longer hold the airplane, and it began to move forward and turn to the left. As the pilot again tried to reduce the power, the airplane went through a fence and came to rest as it impacted a parked car. The pilot also stated that he forgot about the center lock button on the throttle and did not notice that it was engaged during the engine start sequence. He stated the accident was due to "pilot error." Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the throttle was closed, and the mixture control was in the idle-cutoff position. A functional test of the throttle was performed and no anomalies were noted. Additionally, no brake or skid marks were observed on the pavement or the grass. The pilot reported that he had accumulated 1,500 hours of total flight experience, 10 of which were in make and model.