There is described a helicopter having a first member movable with respect to a second member; lubricated supporting means for supporting the first member with respect to the second member; and a primary lubricating circuit for lubricating the supporting means and in turn having primary storage means for accumulating a lubricating fluid, and primary fluid feed means for feeding the lubricating fluid to the supporting means; the helicopter also has an auxiliary lubricating circuit supplied continually by the primary storage means with a first lubricating fluid flow value, and itself continually supplying the supporting means with a second lubricating fluid flow value lower than the first value, so as to produce an auxiliary storage volume of lubricating fluid for use in the event of breakdown of the primary lubricating circuit.