November 25, 2010 – HAPPY THANKSGIVING!
Yesterday I drilled the leading edge ribs to the main spar. The easiest way I found to do this right now was to open one side of the leading edge skin. This would give me access so I could place clecos on the inside.
I celebrated this morning by drilling the joint plates and inboard ribs for the leading edges. The joint plates are strips of aluminum which will connect the fixed leading edge to the fuel tank on each wing. Lots of fun because you have to fit pieces together where there’s not a lot of space.
I did the first one yesterday and figured out how to do it. This morning I did the other one and took pictures of the steps. I know that people do this different ways, but this is what worked for me and it wasn’t all that difficult.
I started out by measuring 3/10″ from the rivet holes in the spar. I arrived at this figure because the rib flanges are .6″ wide. .3″ would be half of that width, and would represent a safe edge distance for the rivets.
I put the end rib in place, lining the inboard (visible) end with the marks I made, then I drilled the rib flange from underneath.
You then mark 1/2″ on the joint plate. This will be the fastener line through the rib, and will allow the plate to stick out 11/16″ past the skin. This will be where the outboard edge of the fuel tank attaches. I also made a line on the rib flanges at about the halfway point. This would provide an indication of safe edge distance.
The plate then needs to be somewhat pre-bent to fit around the nose of the rib. I did this by using a couple of cleco clamps to hold the plate to one of the ribs, and just bent it around. Precision does not matter at this point.
the plate is then slid into place between the rib and the leading edge skin. This is very tight, and you have to tap the plate into place. I experimented with different ways of doing this, but the simplest way was to insert the plate at the top, then slide the sides in. When the plate is in all the way around, look through the holes in the skin to find the line at 1/2″ on the plate. When it is in place, you should have 11/16″ sticking out from the skin for the tank attach.
Because it’s hard at this point to know exactly where the rib is aligned, I used a scrap piece of titanium (stainless works too) to just drill through the skin fastener hole into the plate.
Once that hole is drilled, you can look for the line drawn on the flange of the rib, center it in the hole, and drill it.
Cleco that hole, check the location on the interior, and drill the rest.
I actually drilled the bottom hole on each side, then picked up a hole about halfway up each side, then a top hole on each side. Once those are done, nothing will move, and you can safely drill the rest of the fastener holes without using the titanium or stainless.