An aircraft having a propulsive power unit supported in a fuselage mounted
configuration and including an engine and a nacelle structure housing the
engine. The nacelle structure is provided with upper and lower
displaceable nacelle portions, such as thrust reverser cowls and fan cowl
doors which are displaceable between closed dispositions which they occupy
during operational conditions of the aircraft and open dispositions which
they take up to provide access to engine components. The upper and lower
nacelle portions are so mounted as to be displaceable to their open and
closed dispositions in movements in which one is assisted by gravitational
force and the other is displaced against gravitational force. A force
transfer mechanism is provided for transfer during opening and closing
movements of the nacelle portions of gravitational force assisting
displacement of one of the nacelle portions to assist in displacement of
the other nacelle portion being displaced against gravitational force.
