On August 14, 1999, about 1400 hours mountain standard time, an experimental Kilpatrick IV-1200, N843K, ground looped during landing at Springerville, Arizona. The commercial pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The commercial pilot and one passenger were not injured; the airplane sustained substantial damage. The personal local flight departed about 1215. Visual meteorological conditions prevailed, and no flight plan had been filed. On November 20, 2001, the accident came to the attention of the Federal Aviation Administration, Scottsdale Flight Standards District Office, which then notified the Safety Board. The pilot stated he completed nine touch-and-go landings, and planned to make this landing a full stop. During the transition to tail down during the landing rollout the airplane veered off the left side of the runway. One wheel dug into the wet dirt and the airplane ground looped, which resulted in substantial damage to the right wing spar. The pilot observed clear skies, no precipitation, no obstructions to visibility, and light and variable winds.