On December 5, 1997, about 1120 Alaska standard time, a Bell 206B helicopter, N83146, sustained substantial damage during a practice autorotation landing at the Campbell Airstrip, Anchorage, Alaska. The helicopter was being operated as a visual flight rules (VFR) local area government proficiency flight under Title 14 CFR Part 91, when the accident occurred. The helicopter is registered to, and operated by, the State of Alaska. The first pilot, seated in the right seat, and the second pilot, seated in the left seat, both certificated commercial pilots, were not injured. Visual meteorological conditions prevailed. The flight originated at Merrill Field, Anchorage, Alaska, at 1030. The first pilot, a Fish and Wildlife Protection Officer, and the second pilot, a pilot for the Alaska State Troopers, reported they were performing practice touchdown autorotation landings to maintain their proficiency. The first pilot had performed several, straight-in, touchdown autorotations to snow covered terrain. During the last autorotation, the first pilot entered the autorotation at 800 feet above the ground, and about 80 knots. He indicated during the descent he maintained a 65 knot airspeed, and began a deceleration flare about 50 to 60 feet above the ground. As the ground speed dissipated, the pilot leveled the helicopter, applied main rotor collective pitch, and touched down with about a 30 foot ground run. As the helicopter slowed to a stop, the pilot indicated the helicopter shuddered several times. Examination of the helicopter after landing revealed the main rotor blades struck the tail boom. The tail assembly, consisting of the horizontal and vertical stabilizer, and the tail rotor assembly, was severed from the tail boom.