On March 26, 2005, about 0830 Pacific standard time, a Robinson Helicopter Company (RHC) R22 Beta, N820SH, impacted terrain following a loss of engine power during a practice autorotation near Los Banos, California. Silver State Helicopters, LLC., North Las Vegas, Nevada, operated the helicopter as an instructional flight under the provisions of 14 CFR Part 91. The flight instructor and the commercial pilot student were not injured. The helicopter was substantially damaged. Visual meteorological conditions prevailed, and a flight plan was not filed for the cross-country flight that originated from Los Banos around 0800. The flight was destined for Gustine, California. The instructor pilot reported that shortly after departing Los Banos, he simulated a loss of engine power. The student, who was studying to become a flight instructor, initiated an autorotation to a field. When the instructor attempted to apply engine power following the practice autorotation, the engine "immediately quit." The instructor applied full collective to cushion the landing, but the helicopter landed hard in the field, structurally damaging the tail boom and the fuselage. Following the accident, the operator returned the helicopter to their facility and test ran the engine. No anomalies were noted, and they believed the conditions were suitable for the development of carburetor ice during the autorotation. Review of archived weather data for the day of the accident revealed the weather observation facility at the Merced Municipal Airport, which is 24 miles northeast of the accident site, reported the temperature and dew point as 6 and 5 degrees Celsius, respectively. Plotting of those temperatures on a carburetor icing probability chart revealed that conditions likely existed for serious icing at any power setting. The accident was reported to the Federal Aviation Administration's (FAA) Fresno Flight Standards District Office on August 23, 2005. FAA personnel informed the National Transportation Safety Board of the event on August 24, 2005.