What happened
During an international cargo operation, a twin-end turboprop was conducting a descent under night visual meteorological conditions. After being cleared by air traffic control to descend to 7,000 feet and subsequently 3,000 feet for an ILS approach, the aircraft began a sequence of maneuvers at approximately 7,300 feet and 290 knots. The aircraft entered a shallow left turn, followed by a 45-degree right turn, which transitioned into a rapid, uncontrolled descent. During this descent, the aircraft broke up at an altitude of roughly 1,500 feet over uneven terrain. There were 0 fatalities reported among the crew, though the aircraft was destroyed.
Investigation into the wreckage was significantly hindered by the fact that the aircraft was not equipped with a flight data recorder or a cockpit voice recorder. Furthermore, the aircraft lacked avionics with nonvolatile or downloadable memory, leaving investigators with limited data regarding the specific cause of the loss of control. While the aircraft was loaded within its weight limits and no mechanical failures were identified in the engines or flight control surfaces, the structural failure of the wings and horizontal stabilizers occurred during the descent.
Findings
Investigators found no evidence of preexisting mechanical anomalies, such as engine failure, propeller issues, or runaway pitch trim. The fuel cross-feed valve was closed, suggesting that a fuel imbalance was not a factor in this instance. Evidence indicated that the flight crew likely attempted to recover the aircraft from the descent, possibly by lowering the landing gear to increase drag or by applying heavy back-pressure on the yoke. It is believed that the crew's recovery efforts placed the wings broadside against the relative wind, leading to the structural failure of the wings and stabilizers, which subsequently caused the propellers to strike the fuselage.