Abstract: A coupler/decoupler is suitable for connecting one mechanical system to another and, upon application of sufficient force, resettably disengaging the first mechanical system from the second. In particular, the coupler/decoupler couples the pilot's or co-pilot's controls to the primary flight control system in a helicopter. In the event that the primary flight control system jams, applying a selected force to the controls causes the coupler/decoupler to disengage the primary flight control system, allowing the control to move again. In addition, the coupler/decoupler is configured to transmit a signal when the primary flight control system is disengaged, which activates a backup flight control system.