Abstract: A method of testing an actuation system for positioning an actuator, the actuation system including a primary electronic system, a secondary hydro-mechanical system is disclosed. The method includes the steps of measuring the actual position of the actuation device as set by the primary electronic system; measuring the system inputs and computing an ideal actuator position based thereon; determining the difference between the actual actuator position and the ideal position. The difference is then compared to a first threshold value which represents a disturbance beyond which the system cannot safely operate. Control is transferred from the primary control to the secondary control if the difference exceeds the first threshold. If the difference is less than the first threshold, the difference is compared to a second threshold value which represents an operating condition that can be tolerated for a period of time.