What happened
On May 22, an aircraft operating under a military contract for Civil Air Movement arrived at Cheyenne, Wyoming, from New York International Airport. Following servicing and a weather briefing that included several severe weather warnings, the crew prepared to ferry the plane to Chicago. The flight departed Cheyenne at 0132 on an instrument flight plan, climbing to 7,000 feet via Green Airway 3 and Red Airway 42.
The aircraft was flying without passengers or cargo, with its center of gravity within safe limits. Throughout the flight, the crew provided routine position reports while passing over Sidney, North Platte, Grand Island, and Omaha, Nebraska. At 0337, the pilot reported being over Omaha at 7,000 feet. Shortly after, the crew requested a descent to 3,000 feet, but air traffic control denied the request due to a westbound aircraft operating at 2,600 feet in that sector.
After receiving updated weather information for the route toward Chicago, no further radio communication was established. At 0517, Des Moines tower officials were notified via telephone that an accident had occurred. The impact resulted in two fatalities and the total destruction of the aircraft.
Findings
Investigation into the crash determined that the primary cause was the separation of the right aileron tab motor from its support bracket. This failure occurred because the outboard trunnion had backed out of its bracket due to insufficient safetying.
As the aircraft encountered severe thunderstorm turbulence, this mechanical failure caused erratic rolling motions. The combination of extreme turbulence and the loss of control led to structural overloading. Specifically, a strong downward force caused the right wing panel to fail at its attachment points to the center section. During the sequence of events, the right wing panel struck the tail group, contributing to the disintegration of the aircraft's structure.