On March 14, 2007, about 1207 mountain standard time, an experimental amateur-built Pietsch IT airplane, N214GP, experienced the disconnection of its right rudder cable control while the pilot was maneuvering near Douglas, Arizona. The airline transport certificated pilot had built the airplane. He operated it as a local flight under the provisions of 14 CFR Part 91, and it originated from Douglas about 1200. The pilot was not injured; the airplane sustained substantial damage during landing. The pilot reported to the National Transportation Safety Board investigator that he was practicing for an air show. Following the disconnect, he proceeded to land on runway 21 at the Douglas Municipal Airport. When he was unable to maintain directional control during rollout, the airplane swerved off the south side of the runway whereupon it entered an adjacent soft dirt area, and nosed over. The airplane's canopy broke, and the top of the rudder bent, substantially damaging the airplane. The pilot reported that an examination of his airplane revealed that the right rudder cable separated where two sections had been connected with a turnbuckle. The separation probably resulted from safety wire in the cable's turnbuckle chaffing against the rudder pedal until the wire broke. Thereafter, the turnbuckle unthreaded from the cable ends, and the cable separated. The safety wire's total time since installation was about 240 hours.