On December 22, 2000, approximately 1100 central standard time, a Robinson R-22B2 helicopter, N7158M, registered to and operated by Sky Helicopters Inc., Garland, Texas, was substantially damaged following a rollover while hovering within a practice area at the Mesquite Airport, Mesquite, Texas. The certified flight instructor (CFI) received minor injuries, and his student pilot received serious injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the 14 Code of Federal Regulations Part 91 instructional flight. The flight originated from the Garland Municipal Airport, Garland, Texas, at 1030. Following about 30 minutes of uneventful basic flight instruction, the CFI and student pilot proceeded to Mesquite Airport to accomplish hover practice. After landing on the taxiway for runway 17, and giving a brief about hovering, the CFI moved the helicopter to a grass covered practice area adjacent to the taxiway. The student then practiced hovering for about 3-4 minutes, with guidelines that the CFI would stabilize the helicopter and then transfer control to the student pilot. The CFI then landed the helicopter to give the student a short rest. Shortly after liftoff to a 10-foot hover, the CFI transferred control to the student. The student then "jerked" back on the cyclic and the tail rotor struck the ground before the CFI could regain control. As the helicopter "spun" to the right, the CFI attempted to reduce the throttle and lower the collective. The helicopter came to rest on its left side and both occupants evacuated. The helicopter sustained structural damage to the tail boom, cabin, and main rotor system. The student pilot had 2 hours of total flight time at the time of the accident. It was the student's second instructional flight.