It is known that the flying command calculators perform amongst other, the position feedback control of the control surfaces in an aircraft, for example a transport airplane. The control surface movement is generated by an actuator that could be either in an active mode or in a passive mode. Two actuators are generally provided by a control surface. A so-called “master” calculator performs the feedback control by sending a command to the active actuator. The other actuator, being associated with a second so-called “slave” calculator is forced into a passive mode to follow the control surface movement. If the master calculator detects, thru specific monitoring means, a failure, it switches the active actuator into a passive mode and hands over to the slave calculator that controls the second actuator (switched then into an active mode).
Within the feedback control loop in position, from the flying command calculator to the actuator, including at the level of both such elements, different members or elements are found, which are adapted to generate, in a failing mode, a signal leading to the uncontrolled movement of the control surface. The uncontrolled movement of a control surface, depending on the aircraft flying point, can have consequences on the guiding of the latter and on the sizing of the structure thereof due to the loads being generated. It is thus necessary to be in a position to detect and passivate such a failure very quickly, i.e. before the position of the control surface is too important, the passivation action consisting in limiting or stopping the effect of the failure so as to avoid the propagation thereof.