Rotary wing aircraft provided with propulsion means, and a method applied by said aircraft

An aircraft provided with a power plant driving a rotary wing and at least one propulsion means possessing a propeller, said power plant including at least one engine having an outlet shaft driving a drive train in order to drive said rotary wing, said drive train including one main freewheel per engine, wherein the aircraft includes one coupling member per engine provided with a drive shaft and with a first toothed wheel that are coupled together by a clutch and by a main controllable freewheel arranged in parallel with the clutch, said drive shaft driving at least one propulsion means provided with brake means for braking its propeller, said first toothed wheel meshing with said drive train, said main controllable freewheel operating either in a disconnected mode in which a driving portion of the main controllable freewheel can under no circumstances drive a drivable portion of said main controllable freewheel, or else in a connected mode in which the driving portion drives the drivable portion as soon as a first speed of rotation of the driving portion becomes greater than or equal to a second speed of rotation of the drivable portion, whereas conversely the driving portion is not suitable for rotating said drivable portion when the first speed of rotation is less than the second speed of rotation.