Small Amount of work done on the Leading Edge

Life and weather getting in the way again. After enduring a snow storm yesterday, the weather finally warmed up enough to get out and do something on the airplane. Unfortunately that "something" was pretty minor. I finally decided to redraw the lines on my LE for the rivet line, cut line, and nut plate line.

In a prior post when I did this the first time, I noted that when I performed my trick to extend the cut line from one side of the Le to the other using a file folder as a flexible straight edge, I was not happy with how the lines were close, but not quite lining up with each other correctly. SO I vowed to correct this problem at a later time. Well, that time was now. At that time I commented that I had made my marks by referencing both sides of my best guess as to a centerline based on the centers of the rivet holes on both sides of the skin. I reasoned that I might not have accurately measured the lines on the top and bottom of the skin, and that may have been the reason the lines were slightly off when I tried to join them together with the file folder trick. So I surmized that the next time I would use measurements from a single reference point - that being the inboard edge of the LE skin. ALL measurements for both sides of the skin would be taken using the inboard edge of the wing skin as the reference point.

I had to take some isopropyl alcohol to remove the previous permament Sharpee lines. Works great for removing the so-called "permanent" marker. After that was done I set out to recreate the lines using the inboard edge of the LE skin this time. I started with the bottom side of the LE. I removed the necessary clecoes ad then suddenly realized why my line measurements s might have been slightly off. The very first rivet holes closest to the Actual LE of the airplane are in a very slightly different location than the line of the remaining rivet holes. this is because this very first hole goes through a single tab flange in the forward-most part of the rib. This tab is not as wide as the rest of the main part of the rib flange because this nose area of the rib is gradually reduced as it forms the very tip of the rib, and then it begins to widen again as it wraps around the the other side of the rib. I believe that this occurs as a result of the rib forming process at the factory, where slots are cut into the rib flange area BEFORE the flanges are bent, and they must also be cut at an angle to each other to avoid interfering with each other as the flanges are bent around the semi-circular form of the curve of the LE. Each successive rib flange TAB gets a little smaller than the previous one, until the curve is completed and the flanges can resume a more normal, flatter shape.

As a result of this reduction in flange surface area, the rivet hole of that very first hole ends up being about 1/16th of an inch offset from the other rivet holes. So I think I may have made an incorrect measurement by measuring the distance from the very first set of rivet holes, which obviously would have forced the line from the other rivet holes to be adjusted by that 1/16th of an inch offset, which is why my lines did not match up to each other very well. So the lesson learned from that experience was NOT to use the forward-most rivet holes as a basis for measuring any lines that originate from the other rivet holes further back along the rib.

With that now understood, I proceeded to re-measure the lines again. the numbers, starting with the edge of the LE skin near the second rivet hole (not the first), was about 1 and 1/16 inches from the edge of the skin. This still left a 3/4 inch distance between the rivet hole and the first line known as the rivet line. the second measurement taken from the inboard edge of the LE skin was 9 and 9/16th of an inch. This marks the rivet line on the more outboard line as measured from the inboard edge of the skin, instead of from the rivet hole from the rib line on that outer section of the LE skin. This also results in s 3/4 inch spacing of the rivet line and the rivet holes of the second rib, which matches the spacing on the inboard rib flange. So far so good.

With both rivet lines drawn correctly this time, I was able to measure the same 5/16 inch spacing for the remaining inboard and outboard cut lines and nut plate lines on the inboard and outboard side of the LE skin. Just need to make another file folder flexible straight edge and confirm that the lines on the top and bottom of the LE skin on the inboard and outboard sides now line up as expected. This has to be the case before I finish this exercise by marking and drilling the initial holes for the new rivets and the nutplates that will need to be added.

Lots more work coming up on the fuel tanks, and some orders to place at Vans and a few other places for some parts and supplies that I need, including some special 90 degree corner nut plates for a #8 screw. More later.

KPR