Horizon Air Flight 2185

The operator reported that shortly after departure the first officer noted stiffness in the flight controls when attempting to roll the airplane to the left. After assessing the situation, the captain elected to continue the climb. Shortly after level off, the crew noted that the stiffness increased proportionally with airspeed. This was also noted during the descent phase of the flight, specifically, the first officer stated the resistance increased for left roll inputs as the aircraft accelerated. The captain reported that they attempted to relieve the pressure with aileron trim, however, when the trim indicator reached the first index on the indicator, the control wheel "snapped" approximately 25 degrees and the airplane banked to the right. The crew reported that as the airplane slowed, while on approach, the roll control stiffness decreased. After landing, the crew accomplished a full control check and noted no abnormal indications with the ailerons or spoilers. Post flight inspection disclosed a number of discrepancies that are believed to have contributed to the stiff flight controls. The items are as follows: the right control yoke chain tension was high; the right aileron spring tab hinge bearing did not rotate freely; the left aileron spring tab aft spring tension was low and the contact stud was worn; the right aileron spring tab tension was low and the contact stud was worn; the left aileron hinge bearing did not rotate freely.

Verbatim NTSB analysis and probable cause from the NTSB dataset