A gas turbine engine has a surface cooler having a cooler member defining a fluid passage and at least partially contained in an airfoil shaped flow guide member. The cooler member is disposed within a bypass duct and supported on one of the duct walls. The flow guide member provides a smooth outer surface to guide a main portion of a bypass air stream passing over the surface cooler, and defines an inner air channel between the flow guide member and that supporting one of the duct walls for a secondary portion of the bypass air stream to pass through the inner air channel.
