Abstract: A gas turbine engine actuation system for simultaneously controlling the flow areas defined by two generally coannular ducts, each duct terminating in a nozzle of the variable flap variety. A bell crank pivotable about an axis on the outer (secondary) nozzle is link-connected to the inner (primary) nozzle and also to a translatable actuation ring. The geometry of the flaps, link and bell crank is such that when the secondary nozzle is positioned by the ring and bell crank, the movement thereof is transferred to the primary nozzle to modulate the throat areas defined thereby. Where the secondary (supersonic) nozzle is of the divergent variety extending downstream of the primary nozzle so as to provide a common expansion surface and exit area, a link connection between one of the secondary nozzle flaps and the actuation ring causes simultaneous exit area and throat area modulation in a predetermined relationship.