A method of cooling an aircraft power plant having a combustion engine is disclosed. The method comprises in a first operating mode, inducing a cooling air flow through a heat exchanger in an air conduit via a flow inducing device fluidly connected to the air conduit, the heat exchanger connected in heat exchange relationship with the power plant of the aircraft. The method comprises, in a second operating mode, bypassing the cooling air flow from the flow inducing device via a selectively closable air outlet of the air conduit downstream of the heat exchanger. A cooling system for an aircraft power plant is also disclosed.