On August 27, 1998, at 1545 hours Pacific daylight time, an Aerospatiale SA316B, N605RA, operated by the U.S. Department of the Interior, sustained substantial damage after entangling a bambi bucket in a tree near Porterville, California. The airline transport pilot, the sole occupant, was not injured. The public-use aircraft operating under 14 CFR Part 91 was performing a fire mission at the time of the accident. No flight plan was filed and visual meteorological conditions prevailed. Witnesses saw the helicopter fly down the side of a ridge with the bambi bucket on a 100-foot-long line. The bucket became entangled in some trees and the line snapped and wrapped itself around the tail rotor. The tail rotor blades and gearbox separated from the aircraft and the helicopter spun to the ground and rolled down a steep slope. Witnesses reported that the terrain was mountainous, with 40 to 50 degree slopes. The pilot did not report any mechanical malfunction with the aircraft prior to the accident. A Federal Aviation Administration inspector from the Fresno, California, Flight Standards District Office traveled to the site and reported that there were wire marks on the tail rotor blades and around the output shaft of the gearbox.