On September 23, 2000, at 1515 central daylight time, a Robinson R-22B helicopter, N7183X, was substantially damaged when it impacted the ground while hovering over a grassy practice area on the David Wayne Hooks Airport, Tomball, Texas. The helicopter was registered to and operated by Helicopter Services Inc., of Spring, Texas. The certified flight instructor (CFI) received minor injuries, and the student pilot received serious injuries. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 instructional flight. The flight originated at 1440 from David Wayne Hooks Airport. The CFI reported that the helicopter was in a 3-foot hover with the student pilot on the controls, when the aircraft began to drift "slightly" to the right. As the CFI started to correct by applying left cyclic, the student "abruptly" lowered the collective. Subsequently, the right skid contacted the ground and the helicopter rolled over to the right. Visual inspection of the accident site by an FAA inspector revealed a ground impression corresponding to the right skid. The helicopter's tail boom and main rotor drive system was destroyed. The cabin was substantially damaged. The student pilot had received about 4 hours of helicopter instruction at the time of the accident. He held a commercial airman's certificate with single and multi-engine airplane ratings, and was a certified flight instructor for single and multi-engine airplanes.