COOLING SYSTEM FOR A GAS TURBINE ENGINE

A cooling system (100; 500) for a gas turbine engine (20) comprises an outer engine case structure (106; 506), an inner engine case structure (108; 508) disposed radially inward of the outer engine case structure (106; 506), a plenum (110; 510) extending circumferentially around the outer engine case structure (106; 506) and a heat exchanger (104). The plenum comprises a supply conduit (114; 514) and a return conduit (116; 516) . The supply conduit and the return conduit are in fluid communication with the heat exchanger. The heat exchanger is disposed between the outer engine case structure and the inner engine case structure. The plenum may be configured to provide enhance heat transfer for the cooling system.