A blocker door assembly which may be for a cooling system that may be applied to a gas turbine engine includes a plurality of blocker doors circumferentially spaced about an engine axis. Each blocker door is constructed and arranged to move in a circumferential direction to, at least in-part, control air flow through a passage in an adjacent fixture. A sync-ring is concentrically located about the engine axis, disposed in an annular first duct in direct communication with each passage, and engaged to each one of the plurality of blocker doors for simultaneous operation. The sync-ring is aero-dynamically shaped to reduce surrounding airflow resistance.