US Patent 9644490 Turbine blade tip clearance control

An aircraft engine according to an example of the present disclosure includes, among other things, a high pressure turbine having a blade, an engine casing disposed about the blade, a shield disposed around the casing adjacent to the blade and creating an area between the shield and the casing, and a gate disposed along the shield. The gate is rotatable about the engine casing between an opened position and a closed position for selectively controlling entry of cooling air into the area. A method of cooling an engine is also disclosed.