US Patent 9279341 Air system architecture for a mid-turbine frame module

A mid-turbine frame is disposed between high and low pressure turbine assemblies. A secondary air system is defined in the mid-turbine frame (MTF) to provide cooling to the turbine section of the engine. The secondary air system may be used to cool and pressurize seals to assist with oil retention in bearing cavities. The temperature gain of the secondary air may be reduced by flowing the secondary air through one or more external lines and then generally radially inwardly through air passages defined in the MTF.