On November 8, 1997, at 1220 Pacific standard time, a Bell 206B, N101LF, registered to Hillsboro Helicopters, Inc. of Hillsboro, Oregon, was observed to break up in midair and descend in an uncontrolled manner to a collision with the terrain while performing a 14 CFR Part 133 rotorcraft external-load flight near Forest Grove, Oregon. Visual meteorological conditions prevailed at the time. The commercial pilot-in-command was not injured, and the helicopter was destroyed in the accident and an ensuing post-crash fire. The flight had departed Hillsboro, about three hours prior to the accident. The Federal Aviation Administration (FAA) reported no record of a flight plan having been filed for the flight. In a written statement, the pilot reported that he was returning to the pick-up area for another load. The pilot stated that he was approximately 50 feet above ground level and traveling between 40 and 50 mph when he began the deceleration process. The pilot pulled power back and heard a loud "bang." The pilot stated that warning horns and lights went off as the helicopter turned to the left and rolled right, subsequently colliding with the trees and terrain. A witness on the ground reported that he was waiting for the helicopter to return for another load and observed the helicopter fly over a ridge line in preparation to descend into the basin. The witness stated that 15 to 16 foot trees lined the ridge. When the helicopter was about 120 yards away from his position, he saw the long line cable and bell swing forward and shoot straight up in front of the cabin. The witness stated that the main rotor blades instantly separated and the helicopter started to descend. The witness heard a loud "screaming" sound, then a loud explosion and observed the helicopter come apart in mid-air. The cabin continued in the same direction that it was traveling and turned up-side down and collided with trees and the terrain. The tail section separated and collided with the terrain near where the witness was standing. An FAA inspector from the Portland Flight Standards District Office, Hillsboro, Oregon, responded to the accident scene and reported the following findings to the NTSB investigator-in-charge (IIC). The inspector reported that he observed extensive damage to one main rotor blade, cable marks on the other main rotor blade, one severed tail rotor blade with cable marks, and that the load line itself was severed from the helicopter. The inspector also reported that the hook on the load line displayed severe impact damage signatures.