On February 24, 2002, about 1830 Alaska standard time, a wheel-equipped Cessna 208B airplane, N454SF, sustained substantial damage during taxi, after landing at the Tununak Airport, Tununak, Alaska. The airplane was being operated as a visual flight rules (VFR) cargo flight under Title 14, CFR Part 135, when the accident occurred. The airplane was operated by Grant Aviation, Inc. of Anchorage, Alaska. The solo certificated airline transport pilot was not injured. The flight originated at the Bethel Airport, Bethel, Alaska, about 1750. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on February 25, the director of operations for the operator reported that while en route to the Tununak airport the pilot had received a pilot report, stating that only half of the length of the 2,010 foot runway was plowed. When the pilot braked to a stop on the runway, the nose wheel of the airplane stopped on a snowdrift crossing the runway. When he released the brakes, the airplane started to roll backward off the snowdrift. When he reapplied the brakes to stop the roll, the airplane rocked rearward, pivoting on the main landing gear, and the tail struck the snow-covered ground. The pilot inspected the airplane and found that the tail tie down ring and the aft fuselage bulkhead were damaged. During a telephone conversation with the IIC on March 4, the director of maintenance reported that the two furthest-aft fuselage bulkheads (Station 474.4 and 475.88), and the tail tie down ring and doublers, were replaced due to the damage received in the accident. He said the airplane had no known mechanical problems or damage prior to the accident.