Bombardier Inc CL-600-2C10 N160GJ incident near Kansas City, Missouri

Probable cause

The malfunction of the airplane’s aileron control system due to ice accumulation.

NTSB analysis

The airplane departed in heavy rain and climbed to altitudes where the ambient temperatures were below freezing. During the flight, the crew recognized abnormal turn execution while on autopilot and disconnected the autopilot. Control wheel forces were excessive and aileron response was limited. The crew’s attempts at corrective action, including a roll disconnect to isolate the left and right aileron control circuits, were unsuccessful, and they elected to divert to an alternate airport. While descending, high control wheel force input by the flight crew resulted in the left aileron control returning to normal operation. A few minutes later, the ambient temperature rose to above freezing and an uneventful landing was made. Examination of the control system did not reveal any areas where binding had occurred; however, the events of the flight were consistent with water accumulating in the aileron control system, freezing at higher altitudes, and temporarily binding the aileron control system.

Text from the NTSB. Open the NTSB docket for CEN10IA219 for the full record.