Leading edge ribs Preliminary assembly


The photo above left shows the six ribs that will be installed in the RH leading edge.  At right I have assembled the leading edge with clecos to make sure that everything is in alignment.


W-423 joint plate W-423 joint plate, another view


The two photos above show the W–423 joint plate in work.  This part is a flange which allows the outboard edge of the fuel tank to attach to the leading edge.  It is sandwiched between the inboard rib and the leading edge skin.  The inboard rib of the leading edge is the only rib in the wing that does not come drilled.  This joint plate actually starts out as a strip of sheet metal approximately 2” wide.  It is hand formed to fit.  Care must be taken while drilling to keep the rivet holes in the center of the rib flange.


Leading edge installed on spar Drilling the inboard rib and joint plate


The left photo above shows that leading edge cleco’d to the spar.  The blocks of wood below the spar are to allow the clecos that go into the ribs clearance with the table.  The photo at upper right shows me drilling the joint plate and the inboard rib.  By the way, I am not that vain.  I have learned that the FAA likes to see pictures of the builder while he is working on his project.  That is the only reason that you’ll see me in these pictures from time to time.


Dimpling the leading edge skin Leading edge trial assembly after dimpling


The photo above left shows the leading edge skin during the dimpling process. Dimpling the leading edge was straight forward.  After the ribs were dimpled and the leading edge was dimpled I cleco’d the assembly together to make sure that I did not have any unforeseen problems prior to assembly (photo above right).


Ready for assembly Cleco’d to the spar


The photo above left shows the leading edge cleco’d together and ready for assembly.  Notice that the parts are all primed.  The priming of these parts is covered in the “RH Ribs and Spar” section.  The photo above right shows the leading edge cleco’d to the spar again.  I decided to rivet the leading edge assembly together attached to the spar.  I felt I would have less chance of twisting it. 


In the next four photos the ribs are riveted to the leading edge skin with the entire assembly cleco’d to the spar.  The first photo shows me working on the inboard rib.  The next photo shows me inspecting the rivet shop heads.  I usually replace the inadequate rivets immediately after I inspect them.  In that way I won’t forget to replace them later.  I have noticed that Van’s drawings call out for rivets that are one size or maybe even ½ size, too long.  When shooting a rivet that is too long in a dimpled hole which is loose around the rivet, the rivet shank bends instead of swelling evenly.  Any time any rivet shank bends, either the rivet is too long or the bucking bar is not being held straight.  It is usually the former.  I used a half size shorter rivet then the plans called for on the leading edge.  I didn’t bend any.


Riveting the leading edge Inspecting the rivets
Riveting the leading edge Riveting the leading edge


In the photo above left, I am continuing to rivet the leading edge ribs to the skin.  After I shot as many rivets as I could get to, I removed the leading edge from the spar and placed it in its stand.  I finished riveting the leading edge to the ribs in the stand (above right).  Riveting without a helper takes some practice.  It is very easy to put what is called a “set mark” in the metal.  Since I am building this airplane for enjoyment and relaxation as well as “education and recreation” shooting rivets by myself is actually enjoyable.


Nutplates on the joint plate Riveting the L.E. ribs to the spar


In the photo above left I am riveting K1100-08 nutplates to the joint plate so that the fuel tank can be attached to the leading edge with #8 screws.  I dimpled the rivet holes in the joint plate and the nutplates instead of counter sinking the joint plate.  The amount of effort is about the same but the outcome is much nicer with dimpled holes in the thin sheet metal.  After all of the ribs were riveted to the leading edge skin, I cleco’d the leading edge assembly back onto the spar. 


Riveting the L.E. ribs to the spar Mismatch between tank and outboard L.E.


I felt this was the proper time to rivet the leading edge ribs to the spar.  On the left wing I riveted the trailing edge ribs in place prior to the leading edge ribs.  It then became extremely difficult to rivet the leading edge ribs because the rivet set and rivet gun came in contact with the trailing edge ribs even while using an offset rivet set. The picture above left shows the rear face of the spar after the leading edge ribs were riveted to it. The photo above right was taken after the leading edge and the upper skin were riveted to the wing.  With the fuel tank attached there was a mismatch between the tank skin and the leading edge skin.


Rivets and nutplates removed Shim at topside of joint plate


I determined that the problem was only on the upper surface about the aft 2/3.  I removed all of the upper nutplates.  I also removed all of the rivets on the upper portion of the joint plate.  See the left hand photo above.  I determined that this mismatch could be corrected with a shim of .032” thickness.  I fabricated a shim from .032 2024T3 aluminum.    I drilled the shim to match the joint plate.  I then tapered the forward 1” and slid it between the joint plate and the rib.  See the right hand photo above. Next I riveted the skin, joint plate, shim, and rib together.  I performed A trial fit of the tank assembly and it seemed that my miss-match was gone.  I reinstalled the nutplates onto the joint plate.  I then reinstalled the tank. 


Shim at wing walk doubler Leading edge, fuel tank and upper skin


There was one more area that required a shim.  There is a doubler beneath the upper wing skin across the first four ribs from the inboard.  It’s purpose is to re-enforce the wing skin in this area because you have to stand here to get into the airplane. This doubler creates a mismatch between the upper skin and the fuel tank skin due to the extra thickness.  I fabricated a shim to be placed between the fuel tank skin and the wing spar.  It was made from the same thickness material as the doubler.  I drilled it to match the fuel tank in this area.  I then dimpled the holes for a #8 screw and slid it between the tank skin and the spar.  The mismatch is gone.  The photo at upper left shows the shim and where it goes.  The right hand photo above shows the leading edge attached to the spar and the fuel tank.  The leading edge assembly is complete.  Even though it is obvious that the upper wing skin is installed at this point, we are going to the RH Wing Skin section next.