On July 28, 2003, about 1800 central daylight time, a Champion 7GCBC, N9032L, piloted by a commercial rated instructor pilot, sustained substantial damage when it ground looped during a high speed taxi at Harding County Airport (9D2), near Buffalo, South Dakota. Visual meteorological conditions prevailed at the time of the accident. The instructor and the dual student reported no injuries. The 14 CFR Part 91 instructional flight was not operating on a flight plan. The local flight was originating at the time of the accident. The instructor pilot reported: We were practicing fast taxi for directional control. The aircraft had slowed enough that the tail was on the ground but we were still going fairly fast (25-30 mph indicated). The aircraft started to go right, and I assisted the student in straightening it by applying a small amount of left brake. Then the aircraft started to swerve violently to the left, and I applied full right brake, which didn't stop the motion but may have kept the wing from hitting the ground. We made approximately a half circle, turning about 135 [degrees], managing to stay on the runway the whole time. The aircraft never left the ground. We were using Runway 30 with a light east wind. The instructor reported no mechanical malfunctions prior to the accident and stated that the aircraft sustained damage to the airframe tubing during the accident.