19980729018259A

(.19) On July 29, 1998, at 2248 hour pacific daylight time, a Bell 222B helicopter, N911RA, was destroyed when it landed hard, rolled over, and burned at tranquility, California (approximately 25 statute miles southwest of Fresno). The helicopter was owned and operated by rogers helicopters of clovis, California, and was on an aeromedical evacuation mission when the accident occurred. The commercial pilot and two flight nurses were not injured and no ground property damage was incurred. Night visual meteorological conditions prevailed and a company VFR flight plan was filed. The purpose of the flight was to air-evac two victims of an automobile crash on a local highway. The pilot stated that as he was landing at the location of the highway accident, a cloud of dust churned up by the rotor downwash enveloped the helicopter and he momentarily lost sight of the ground. The helicopter touched down hard on one skid, which broke the strut and cross tube. It then rolled over and caught fire. (From .4) the purpose of the flight was to air-evac two victims of an automobile crash on a local highway. Responding sheriff and fire ground units to the traffic accident set up a landing zone in a farmyard. The pilot and ground witnesses dexcribed the landing zone as a confined dirt lot roughly 150 feet square surrounded by silos, power lines, trees, and buildings. Emergency vehicles were using their headlights to illuminate the landing area and a fire person was functioning as a ground guide for landing. After making three high recon orbits around the landing site the pilot made the landing approach, and, as the helicopter neared touchdown it was 'engulfed in a large cloud of dust very quickly' to the point where visual contact with the ground was lost. The pilot said he tried to focus on the ground through the chin bubble window and added collective in an attempt to climb out of the dust; however the right wheel touched down and the helicopter rolled over. A deputy sheriff 60 feet from the landing spot said that as the helicopter descended from 15 to 3 feet above the ground a dust cloud began to form, which thickened until the only thing he could see of the aircraft was the landing lights and the front wheel. The helicopter suddenly dropped to the ground and bounced on its wheels and then the deputy heard the engine noise increase in pitch and sound. It rose about about 3 feet off the ground, drifted to the right about 6 feet, and then rolled over. The moon was located 10.9 degrees above the western horizon with only 38 percent of the disk illuminated. (-23) the accident occurred during an emergency medical response operation. During the approach to a hover, off airport landing site, the pilot lost visual contact with the ground. The restriction to visibility was caused by the helicopter's downwash which created a dust cloud. The right main tire and assembly was sheared off and then the helicopter apparently experienced dynamic roll over. There were no injuries and no post fire evidence was observed.