On March 5, 2004, at 1738 Pacific standard time, a Robinson R22 Beta, N7188S, rolled over while practicing a hovering autorotation at Long Beach-Daugherty Field (LGB), Long Beach, California. Los Angeles Helicopters was operating the helicopter under the provisions of 14 CFR Part 91. The certified flight instructor (CFI) sustained minor injuries, and the student pilot was not injured; the helicopter sustained substantial damage. The local instructional flight departed LGB about 1630. Visual meteorological conditions prevailed, and no flight plan had been filed. The primary wreckage was at 33 degrees 49 minutes north latitude and 118 degrees 09 minutes west longitude. The CFI reported that while practicing hovering autorotations, the student pilot was manipulating the controls with the CFI following along. The autorotation prior to the accident resulted with the student pilot applying improper left cyclic input. The CFI identified the improper action to the student, and told him to try it again. On the accident hovering autorotation, the student was the sole manipulator of the controls. He landed the helicopter and maintained the heading; the CFI did not perceive any lateral movement. Then the CFI realized that the helicopter was starting to roll to the left. The CFI applied full right cyclic, but the helicopter continued to roll slowly until the main rotor blades contacted the ground. The helicopter came to rest on its left side. The pilot and operator submitted a Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2). The CFI stated that the airplane had no mechanical failures or malfunctions during the flight.