A gas turbine engine includes a core cowl and a core contained within the core cowl. The core includes a compressor in fluid communication with a downstream combustor and a downstream turbine, the compressor including a compressor bleed port, wherein an undercowl space is defined between the core cowl and the core. The gas turbine engine further includes a cooling duct disposed at least partially in the undercowl space and having an inlet and an outlet, wherein the cooling duct is in fluid communication with a source of cooling air and is further in fluid communication with the compressor bleed port; a valve assembly including at least one valve disposed in the cooling duct; and a cooling blower disposed within the engine and operable to move an air flow from the inlet of the cooling duct towards the outlet of the cooling duct and through the compressor bleed port.