To keep the rivets mounting the slider blocks away from the radius of the rib lightening hole flanges, two new rivet holes were added to the slider blocks near the center on each of the four sides. This pair of rivets on each side, was positioned an additional ¼” away from the centerline. See image #3.
To locate the slider blocks on the centerline of the lightening hole, a scrap piece of 2” aluminum tube was inserted into the center of a roll of drywall mesh tape. The OD of the roll was adjusted to be a snug fit inside the lightening hole by stripping off excess tape until a good fit was achieved. One turn of the tap was applied to tube to provide a snug fit to the ID of the slider block.
The rivet holes were then transferred from the slider block to the rib, then to the other three ribs using the process described in the BM. Holes for the pitot tubing were also drilled in the left wing ribs.
