On September 28, 2003, about 1200 eastern daylight time, a Robinson R-22A, N56MU, was substantially damaged when it impacted the ground while hovering at Laurence G. Hanscom Field, Bedford, Massachusetts. The certificated flight instructor (CFI) and a student pilot were not injured. Visual meteorological conditions prevailed and no flight plan had been filed for the instructional flight conducted under 14 CFR Part 91. The student pilot had accumulated about 3 hours of helicopter flight experience. According to the CFI, the student pilot was practicing hovering, when the helicopter descended "too low." The helicopter momentarily contacted the ground while drifting to the right, and rolled over. The CFI stated he did not experience any mechanical malfunctions. He reported 1,059 hours of total flight experience, which included 641 hours in helicopters, and 471 hours in make and model.