Abstract: Control apparatus of the kind disclosed in UK patent specification Nos. 2,073,887 and 2,114,717, i.e. in which a movable operating member, arranged to control associated apparatus such as an aircraft engine, is coupled to an electric stepper motor, the motor being energizable to move the operating member and/or to generate a `feel` resistance to, or detents in, the manual movement of the operating member, the apparatus including a ball-screw assembly comprising a lead-screw and ball-nut, one of which is connected to the operating member and, with the operating member, is linearly movable with respect to the other, the stepper motor being coupled to the ball-screw assembly so that rotation of the motor rotor produces, or is produced by, relative rotation of the lead-screw and ball-nut.