The perils of doing a LE mod - continued

I measured and marked some holes for the left wing leading edge. the hole spacing for the W-408-1-L leading edge is different from those on the W709 rib that normally goes in the location that I am having to modify by using the different rib. This, combined with the fact that the rib-to-skin flanges on the top and bottom of the 408 rib are slightly shorter than the ones on the W709 rib, has created a situation where there is not enough material on the rib flange to locate  the top and bottom rib flange holes that are closest to the wing spar flange.

Therefore my solution is to move the hole up about 1/4 inch so there is enough rib flange material to attach a rivet. This is where the top side final rivet hole ended up when I match drilled using the LE skin:

As you can see the last hole is right on the bottom of the flange = no good for riveting. This is the result of having to use a rib with a shorter flange and trying to match drill the existing holes in the LE skin, which were originally spaced for the W-709 rib, and not this one. Here is the hole in about the same place on the bottom of the flange:

The "minimum-effort" solution to this problem involves removing the material around the last hole on both flanges. I then measured for a new hole about a 1/4 inch above the top of the old hole that will be removed. I then applied the same measurements to the top and bottom of the LE skin as shown in the next series of pics.

The above pic shows the distance for the original W408 rib's rivet holes on the inboard edge of the LE skin. The hole on the left is the rivet hole that attaches the skin to the top wing spar flange (not the rib flange). The next hole to the right is about 1.5 inches from the center of the wing spar flange hole, and the rest of the holes are spaced about 1 inch apart until you get to the bottom of the rib, where the last two bottom holes will be 1.5 inches apart again.

This next pic is the measurement of the hole pattern in the LE skin for the original W709 rib. I am using these same holes for the new rib as much as possible to avoid having to drill new holes in the skin. These holes are spaced a little further apart because this rib does not have to provide support for the fuel tank support like the other inboard rib does.

All of these holes appear to be about 1.25 inches apart, including the wing spar attach hole to the first rib flange hole. Basically the new rivet hole will be drilled about 1.4 inch above the top of the first rib flange hole. Then I plan to fill the hole shown in the pic (first flange hole to the right of the wing spar attach hole) with a small rivet just to close the hole. It will not be attached to anything.

The next pic is the marks on the rib flanges for the new holes:

The line on the top of the hole will be the cut line to remove the bottom hole from the flange. I need to maintain 1/4 inch edge distance from the end of the flange. This is where the second line was drawn. I will predrill the new holes in the wing skin, then match drill the new holes through the skin with the entire Leading edge assembly clecoed and attached to the wing spar.

The flash from my camera washed out the lines a bit, but you get the idea. These are the new holes in the LE skin top and bottom that will be drilled (where the sharpee lines cross).  I did not want to drill them tonight as I am tired, and I definitely do not want to screw any of this up, So I will drill the new holes in the skin and remove the ends of each 408 rib to skin flange tomorrow.

Until next time......KPR