AMC 22.411(a) Control system stiffness and stretch

CAA ORS9 Decision No. 1

Control systems will normally be accepted as complying with paragraph CS 22.411(a) if they meet the following:

Under the application of the loads prescribed in CS 22.395, no part of the control system should stretch or shorten by more than 25%. The stretch percentage is defined as De = 100 a/A where:

a = comparable movement of the cockpit controls when the pilot effort is resisted by fixing the control surfaces at their zero settings

A = available positive or negative movement of the cockpit controls (measured from their neutral position) when the control surface and the control mechanism are free.

However, stretch or shortening greater than 25% may be acceptable provided special attention is given to compliance with CS 22.143 and CS 22.629 in these conditions.