A method for controlling turbine blade tip seal clearance on a non-cowled gas turbine engine includes the step of directing a flow of relatively hot, pressurized air in contact with an exterior surface of the engine core casing circumscribing the turbine. The flow of relatively hot, pressurized air may be selectively directed in contact with the exterior surface of the engine core casing circumscribing the turbine when it is desired to expand the turbine shroud radially outward, such as during transient operation of the gas turbine engine.