A heat exchanger for an aircraft engine includes: a body including a plate-like first member and a plate-like second member that are stacked in a thickness direction of the first and second members and joined together, and a channel which is defined in the body and in which the cooling target fluid flows; and a corrugated fin plate disposed in the channel in the body. An opening portion is defined in a reverse concave shape at one lateral side of a cover. The position of the proportional valve is controlled by one or more high speed valves to control various engine valve parameters, including engine valve takeoff and landing velocities.