Shortly after takeoff in a strong crosswind, the pilots of a De Havilland Canada Dash 8-402 noticed that both handwheels (control wheels / yokes) were offset to the right in order to maintain wings level flight. The aircraft diverted to Exeter Airport where it made an uneventful landing.
The handwheel offset was the result of a break in a left aileron cable that ran along the wing rear spar. In the course of this investigation it was discovered that the right aileron on G-FLBE, and other aircraft in the operator’s fleet, would occasionally not respond to the movement of the handwheels. Non-reversible filters were also fitted to the operator’s aircraft that meant that it was not always possible to reconstruct the actual positions of the control wheel, column or rudder pedals recorded by the Flight Data Recorder.
The aircraft manufacturer initiated safety actions to improve the maintenance of control cables and to determine the extent of the unresponsive ailerons across the fleet. Three Safety Recommendations are made in this report for the unresponsive aileron and filtering of the control position data.
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Published 15 October 2020
