A nacelle cooling and ventilation system for an aircraft gas turbine engine which includes a chin scoop and duct assembly for directing air through the engine bay where it is exhausted into the engine exhaust through an exhaust shroud eductor. The nacelle is enclosed so that effectively all of the cooling air entering the bay leaves the bay through the engine exhaust and is not dumped overboard, thereby adding to the effective thrust of the engine. An engine oil and generator oil heat exchanger is positioned in the cooling air duct into the bay so that the same air which cools the bay also cools engine and generator oil. The oil heat exchanger includes directional louvers which regulate and keep to a minimum the amount of cooling air and direct cooling air forwardly in the bay so that the entire bay area is cooled, and which can be shut as a fire control measure. The nacelle includes bay vent doors which are opened in response to a high oil temperature condition or in an engine shut-off condition on ground to provide auxiliary air flow from the bay. The doors are positionable by an actuator but can be disconnected from the actuator to pivot freely in response to a sudden increase in nacelle bay pressure.
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