The present invention includes a balancing system that includes a weight box, mounted substantially within the rotor-blade spar, flush with a rotor-blade spar outer surface, operably accessible from a rotor-blade tip, and retained within the rotor-blade spar by a weight-box retention pin, one or more weight-box contact surfaces bonded to a rotor-blade-spar inner surface, or a weight-box lip providing a bearing contact with an edge of a spar rotor-blade spar cutout; and a weight package attached to the weight box, the weight package including a weight-box cover, two or more weight guide-rods attached to the weight-box cover, wherein one of the two or more weight guide-rods is positioned forward of a pitch change axis or center of twist and wherein one of the two weight guide-rods is positioned aft of the pitch change axis or center of twist, and one or more balance weights mounted on the weight guide-rods.