Transport Canada CF-2020-29

Requires repetitive visual inspections of elevator torque tube bearings and functional tests of the elevator control system to detect and replace contaminated bearings. Prompted by two in-service findings where both the left -hand and right-hand elevator torque tube bearings were contaminated with sand and corroded, restricting free rotation. Left uncorrected, sand contamination of the elevator torque tube bearings could lead to binding or seizure of the bearings and potentially a reduction in or loss of airplane pitch control. Findings of the inspection and functional tests must also be reported to Bombardier to assist in the investigation of this issue and possible development of alternative or additional corrective actions.