On June 23, 2004, about 0900 Pacific daylight time, a Bell 47G-3B-1, N73909, registered to DSM Inc., operated by Pacific Air Research as a 14 CFR Part 137 aerial application flight, collided with trees and terrain located about 14 nautical miles southwest of Medford, Oregon. Visual meteorological conditions prevailed at the time and no flight plan was filed. The helicopter was substantially damaged by impact damage and post-crash fire. The commercial pilot, the sole occupant, was seriously injured. Company personnel reported that the pilot had been dispensing a herbicide in the area for about one hour and 20 minutes prior to the accident. Witnesses in the area reported that the helicopter was returning to the staging area for another load of herbicide when they heard the crash. In a written statement, the pilot reported that while flying over mountainous terrain with a slight slope on the last pass, the helicopter struck a snag (dead tree). The engine lost power and the helicopter collided with the terrain.