The translating sleeve forms the outer surface of each C-duct. In the forward thrust mode, the translating sleeve is held against the form of the C-duct. This gives an aerodynamically smooth surface to the engine nacelle. In reverse thrust mode, the translating sleeve moves aft on tracks near the top and bottom of the C-duct. As the translating sleeve moves aft it moves the blocker doors down and uncovers the cascade, which point the flow of fan air coming in to the duct outward and forward through the cascades.