On January 22, 2000, at 0945 central standard time, a Robinson R-22B, N4047C, operated by WW Helicopters LLC, of East Troy, Wisconsin, sustained substantial damage during an in-flight collision with terrain following a loss of control during takeoff from runway 18 (1,900 feet by 150 feet, snow-covered/grass) at the East Troy Municipal Airport, East Troy, Wisconsin. Visual meteorological conditions prevailed at the time of the accident. The instructional flight was conducted under the provisions of 14 CFR Part 91 and was not on a flight plan. The certified flight instructor (CFI) received minor injuries. The dual student reported no injuries. The local flight was departing at the time of the accident. According to the CFI's written statement, they were practicing a running takeoff on runway 18 and after traversing approximately ten feet of the takeoff run the student applied right pedal input. The CFI stated that he tried to overcome the student's right pedal input by depressing the left pedal and verbally commanding the student to do the same. The CFI reported that he was unable to counteract the students control input and the aircraft yawed to the right. The left skid of the helicopter impacted the terrain, the aircraft rolled onto its left side, and slid 15-feet before coming to rest.