Accident Summary
Shortly after departure and level off, the pilot reported an engine malfunction and initiated a return to the airport. About two minutes later, he reported an engine fire and declared an emergency. Approximately one minute thereafter, the right wing separated from the aircraft and the plane crashed.
Examination Findings
An examination of the wreckage revealed extensive in-flight fire damage in the area of the wing separation. A 2.5 by 3 inch hole was found in the right inboard exhaust tube (part number 0850712-6). The hole was oriented toward the accessory compartment, which contained numerous fuel and oil lines that were fire damaged and charred. Additionally, much of the engine support structure and wing spar were melted in that area.
Further examination of the exhaust tube revealed its walls were thin, brittle, and discolored in the area of the rupture. Several areas of cracks and small holes were also found. The exhaust tube had accumulated 5,862 hours of total service time and 1,762 hours since its last overhaul. Records indicated that Airworthiness Directive 75-23-08 had been complied with during the last inspection, which occurred 25 flight hours prior to the accident.