On March 29, 2003, approximately 1730 Pacific standard time, a Robinson R-22B, N2629Z, impacted the ground during an emergency landing about 10 miles southeast of Mabton, Washington. The commercial pilot and his passenger were not injured, but the aircraft, which is owned and operated by Danielson Aviation, LLC., sustained substantial damage. The 14 CFR Part 91 personal pleasure flight, which departed Pasco, Washington, about 15 minutes earlier, and was en route to The Dalles, Oregon, was being operated in visual meteorological conditions. No flight plan had been filed. According to the pilot, while en route he made the decision to make an off-airport landing in an open field. Reportedly, while he was making a shallow approach, the helicopter experienced a momentary loss of power and the pilot heard a burble noise from the engine. This was accompanied by a low rotor rpm warning and the settling of the aircraft toward the terrain. The pilot then tried to roll the power on further, but the rpm did not fully recover. He was able to hover-taxi about five feet above the terrain for about 50 yards, but when the helicopter began to yaw, he made the decision to attempt to land. During that attempt, with the helicopter moving slightly sideways, the left skid got stuck on a large clump of dirt, and the aircraft rolled over onto its side. During the investigation it was determined that there was approximately 25 gallons of fuel on board at the time of the accident. An inspection of the engine and airframe did not reveal any anomalies that would have contributed to a loss of power.