Positioned W-613 aileron hinge bracket on rear spar so that outboard rivet line was lined up on W-625 stub rib. Drilled bracket to spar w/#30 drill bit. Positioned W-614 aileron hinge bracket on rear spar & drilled bracket to spar. Deburred all holes. Located & marked location of hole in spar by W-613 bracket. Drilled pilot hole & enlarged hole to 3/4" using Unibit. Used 1/8" bit to drill corner holes for spar hole. Filed sides of hole straight to make rectangular hole.