On September 3, 2011, at 1430 eastern daylight time, a Robinson R-22, N7197W, sustained substantial damaged following a ground collision during a practice autorotation at the St. Petersburg-Clearwater International Airport (PIE), St. Petersburg, Florida. The commercial pilot received minor injuries and the designated pilot examiner (DPE) was uninjured. The helicopter registered to and operated by Razor Blades Helicopter Incorporated under the provisions of Title 14 Code of Federal Regulations Part 91 as an evaluation flight. Visual meteorological conditions prevailed and no flight plan was filed. The flight was originating at the time of the accident. According to the commercial pilot, the purpose of the flight was to complete his certificated flight instructors check ride. During the first segment of the check ride, all of the maneuvers were uneventful. The DPE then instructed the pilot to demonstrate a straight in autorotation with a power recovery. The pilot conducted the maneuver but the DPE was unsatisfied and asked the pilot to perform the maneuver again. The pilot performed the maneuver to the satisfaction of the DPE, and was then asked to perform an autorotation with a full stop. During the full stop autorotation as the pilot began to flare to slow the helicopter, the DPE began to shout. The pilot did not understand what the DPE was shouting about and shortly thereafter the helicopter became uncontrollable. The helicopter climbed to the left and the pilot attempted to push the cyclic forward to regain control of the helicopter. The pilot stated that the DPE held the cyclic back, the helicopter collided with the ground, and rolled over on the left side resulting in substantial damage to the helicopter tail boom and tail rotor. According to the DPE this was the commercial pilot's third attempt for this check ride. On the pilot's previous check rides the pilot's slow reaction time caused him difficulty in emergency operations, which resulted in an unsatisfactory performance and termination of the evaluations. The pilot was instructed to perform a touchdown autorotation, and during the maneuver everything appeared to standards. As the flare to touchdown started the pilot did not arrest the sink rate which resulted in a tail low attitude. The tail boom stuck the ground and the helicopter rolled onto its left side. The DPE stated that he did not touch the cyclic control and did not agree to act as pilot in command. According to part 14 Code of Federal Regulations 61.47 Part (b) the examiner is not the pilot in command of the aircraft during the practical test unless the examiner agrees to act in that capacity for the flight or for a portion of the flight by prior arrangement with the applicant.