ENGINE EXHAUST REVERSE FLOW PREVENTION

An aircraft engine (10) includes a core gas path (28) through which a core gas flow (28a) flows, an exhaust duct (30) receiving the core gas flow (28a), an air-cooled heat exchanger (34) disposed in a heat exchanger duct (36, 38) having an air inlet (34a) providing cooling air to the air-cooled heat exchanger (34) and an air outlet (34b) in fluid communication with the exhaust duct (30), and a cover (40) disposed in the heat exchanger duct (36, 38) downstream of the air-cooled heat exchanger (34). The cover (40) is movable between an open position, in which the cover (40) allows the cooling air to flow through the air outlet (34b) into the exhaust duct (30), and a closed position, in which the cover (40) substantially blocks the air outlet (34b). The cover (40) is operable to move from the open position to the closed position at a predetermined temperature of the cover (40).