NPA 2017-18

Unintended or inappropriate rudder usage — rudder reversals

The objective of this Notice of Proposed Amendment (NPA) is to mitigate the safety risk stemming from pilots of large aeroplanes applying inappropriate rudder control inputs, in particular pedal reversals, which may create structural loads that exceed limit loads or even ultimate loads. This may lead to the failure of primary structure and/or flight controls and then to a catastrophic loss of control of the aeroplane.

This NPA proposes to amend CS-25 to:

  • create a new CS 25.353 yaw manoeuvre condition, consisting of a two pedal doublet manoeuvre, and related AMC 25.353, and
  • clarify CS 25.1583(a)(3) regarding manoeuvring speed limitation statements in the aeroplane flight manual, amend the related AMC 25.1581 and create a new AMC 25.1507.

The proposed changes are expected to ensure that large aeroplanes are designed with features protecting the structure against rudder control pedal reversals like the ones demonstrated in several reported occurrences. This proposal would thus ensure an increased level of safety, while creating little or no economic impact in most of the cases.