Accident Overview
On February 15, 1983, at approximately 1100 Mountain Standard Time, a Sierra Pacific Airlines DHC-6 twin-engine aircraft, operating as Transwestern Flight 868, crashed during its final approach to runway 31 at Friedman Memorial Airport in Hailey, Idaho. The accident occurred 1.7 miles south of the airport. The aircraft was destroyed by impact forces, though no fire ensued.
Flight Details
Flight 868 was a regularly scheduled commuter passenger flight from Boise to Hailey, Idaho. On board were two flightcrew members and six passengers. Following the crash, one passenger escaped with minor injuries, while the other seven occupants sustained serious injuries.
Sequence of Events
While approximately 800 feet above the small town of Bellevue, about 2 miles south of the airport, the captain reduced power to configure the aircraft for its final approach. Immediately thereafter, the captain realized that elevator control had been lost. The aircraft nosed over and descended steeply. The captain attempted to control the pitch by adding power, and the aircraft began to recover. However, it crash landed on a highway in a slight nose-down attitude with the right wing slightly lowered. After touching down, the aircraft veered off the highway, struck a 4-foot-high snowbank, and broke apart.
Probable Cause
The official probable cause was the in-flight loss of elevator control following separation of the control rod from the torque tube at a connection where the company's maintenance department had used a non-standard, unsecured bolt, which the company's inspection department had failed to detect. Contributing to the accident was the company's failure to maintain the separation of maintenance and inspection functions required by the maintenance program approved by the Federal Aviation Administration, and the failure of the FAA to detect the company's deviation from approved maintenance procedures during surveillance inspection.