Accident Details
On August 28, 2010, at approximately 1835 Alaska daylight time, a Stinson 108-2 airplane, registration N9569K, incurred substantial damage while executing an off-airport landing approximately 48 miles west of Port Alsworth, Alaska. The aircraft was operated under 14 CFR Part 91 as a personal cross-country visual flight rules flight. Company flight following procedures were active at the time. The commercial pilot, accompanied by two passengers, reported no injuries. Visual meteorological conditions prevailed. The flight had departed Port Alsworth at around 1730.
Pilot Report
According to a written report submitted to the National Transportation Safety Board (NTSB) on September 6, 2010, the pilot stated he was transporting his sons on a camping trip. After surveying a ridge west of Port Alsworth, he chose to land on a tundra area with which he was familiar and had used previously. The pilot reported making three low passes over the landing zone to assess wind conditions and check for new obstacles. Following touchdown and braking nearly to a stop, he was taxiing toward his intended parking spot when the right wheel fractured, causing the aircraft to tip onto its right wing. The wing, wing spar, and aileron sustained damage from contact with the ground.
Investigation Findings
On September 2, 2010, the NTSB investigator-in-charge examined the broken wheel. The wheel was equipped with 35-inch Alaskan Bush Wheels. The center of the wheel casting adjacent to the inner bearing race had fractured around its circumference, allowing the casting piece and bearing race to separate from the wheel, which permitted the axle to pivot. On February 16, 2011, the fractured wheel underwent further examination at the NTSB's materials laboratory. The analysis showed features indicative of overstress separation of the flange. No evidence of fatigue, corrosion, or other preexisting conditions was observed.