Abstract: The present invention provides a method to repair a void in an aluminum alloy, particularly a void resulting from an exit hole left from friction stir welding (FSW). The method includes machining the void to provide a tapered bore (34) through a parent metal, i.e., the aluminum alloy (30), providing grooves and ridges (36) on a sidewall of the tapered bore, inserting into the bore a consumable tapered plug (38) having an included angle less than, or equal to, that of the tapered bore, and rotating the plug inside the bore under an applied load to plasticize both its surface and the ridges on the parent metal tapered bore. The tapered plug is preferably attached at its proximal end to a nonconsumable heat sink (40) to remove excessive heat generated during rotation of the plug. Also, a support bracket is temporarily attached to the aluminum alloy adjacent the tapered bore to receive a distal end of the plug (38) and to react to the applied load.