What happened
While operating at 8,000 feet MSL, the pilot of a cargo aircraft experienced a loss of power in the right engine. Following the engine failure, the pilot notified air traffic control and was provided with radar vectors toward a nearby airport. In an attempt to maintain altitude, the pilot flew at the optimal single-engine rate-of-climb speed; however, the aircraft began to lose altitude.
As the aircraft entered a cloud layer, it began to accumulate structural icing. This accumulation prevented the aircraft from maintaining the necessary altitude to clear obstacles. The flight eventually impacted mountainous terrain approximately 16 miles northwest of the destination airport. At the time of the accident, the pilot reported that conditions were characterized by fog and darkness. The aircraft had departed with five hours of fuel for a planned flight duration of approximately two and a half hours.
Findings
Post-accident investigations of the engines and associated systems showed no signs of mechanical malfunction prior to the impact. Furthermore, an examination of the airframe and its various systems revealed no evidence of pre-impact failure. During subsequent engine testing, the right engine was found to have started normally and functioned as intended. The primary factor contributing to the accident was structural icing accumulation which prevented the aircraft from maintaining altitude following the engine power loss.