On July 1, 2004, at 1500 eastern daylight time, N71409, a Cessna 172M, registered to and operated by Triad Air, Inc., collided with a fence post while taxiing after landing at Smith Reynolds Airport, Winston-Salem, North Carolina. The instructional flight was conducted under the provisions of Title 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed at the time of the accident and no flight plan had been filed. The pilot-in-command, a certified flight instructor seated in the left seat (CFI-left), and the certified flight instructor seated in the right seat, (CFI-right), were not injured. The airplane received substantial damage. The local flight originated at Smith Reynolds Airport, Winston-Salem, North Carolina, on July 1, 2004, at 1330. According to the operator, the flight had taken place prior to the accident for the purpose of an initial checkout for a newly hired flight instructor, CFI-right. According to both pilots, after landing, the airplane was cleared to taxi to the north ramp. Both pilots stated that the CFI-left took control of the airplane in order to position and park it. The pilot in control of the airplane at the time of the accident, CFI- left, stated, "while pushing the left rudder, [his] foot slipped down and off the [left] pedal." He stated that he then immediately "pushed full left rudder, but the right wing... hit one of the corner metal poles." The pilot not in control of the airplane at the time of the accident, CFI-right, stated that as the pilot in control "was beginning to set-up the aircraft's turn, his foot immediately slipped off of the rudder. This caused the aircraft's wing to hit a fence post." Both pilots stated that the airplane was immediately shut down and assistance was sought. Post-accident examination of the airplane revealed that the right wing sustained leading edge spar damage and extensive skin buckling, and the right wing tip was crushed. The engine, landing gear, fuselage, and left wing were intact and undamaged. Examination of the aircraft logbooks revealed that the right wing was replaced per Federal Aviation Regulations and procedures on July 23, 2004. No mechanical problems with the airplane were reported by the pilots. Notification of this accident from the operator was received by the NTSB on August 12, 2004.