An aircraft, including a fixed nacelle disposed on a wing of the aircraft, the fixed nacelle including a nacelle opening; a proprotor pylon disposed on the wing and rotatable relative to the fixed nacelle between a substantially horizontal position and a non-horizontal position, wherein rotation of the proprotor pylon to a non-horizontal position exposes the nacelle opening; and a movable cover disposed on at least one of the wing and fixed nacelle, said movable cover including a plurality of cover members that are movable between a closed position where at least a portion of the cover members collectively form a protective cover in front of the nacelle opening when the proprotor pylon is positioned in the non-horizontal position and a stowed position where at least a portion of the plurality of cover members are stowed. In other aspects, there is provide a method of covering a nacelle opening.