Assemble
8/10/22 – 1.9h
8/11/22 – 1.4h
8/12/22 – 2.5h
8/13/22 – 2.0h
8/14/22 – 4.3h
8/15/22 – 2.1h
8/17/22 – 1.9h
8/18/22 – 1.3h
8/19/22 – 5.2h
This is purely an assembly step starting with the attachment of two nut plates to the web of the left leading edge splice rib. The nut plates will be used to mount the stall warning sensor. I back-riveted the nut plates to the splice rib without any drama despite the fact that it has been a long time since I have done any back-riveting.

There is an inconsistency in the plans for the next steps which say to insert the left leading edge skin into the cradle, cleco the access hatch doubler into place, and then back-rivet the access hatch doubler. Back-riveting isn't an option if the skin is already in the cradle, so I did the back-riveting before putting the skin in the cradle. Back-riveting on the bench works very well for the access hatch doubler. I also took this opportunity to check the fit of the access hatch cover. It was a little tight on the forward and aft edges, so I used a Scotch Brite pad and sandpaper to get it to fit better.

CAUTION: Put a towel or some sort of padding below the area you are riveting. If you drop the bucking bar, you'll be glad the pad is there to protect the skin. If not, be prepared to spend a lot of time working out an inadvertent ding. I fumbled my bucking bar once, which resulted in a medium-sized “outie” where the upper leading edge starts to curve. This was a very difficult location to work, and I spent a long time with a spoon and some elbow grease to work out the dent. There is still a small blemish on the leading edge, but I got it to the point that prep for paint should smooth it out. That was definitely not the way I wanted to spend that work session!

The main riveting starts with the aft 2 holes (top and bottom) on each rib. I used the pneumatic squeezer to set those rivets, and I was very happy with the results. I used the pneumatic squeezer to set the next rivets working toward the front of the piece, also with good results. The furthest aft hole at the splice rib only hits the skin and the splice strip (not the rib), and it uses the same AN426AD3-3.5 rivet as the aft holes for the other ribs. The rest of the holes at the splice rib go through the skin, splice strip, and rib; so the longer AN426AD3-4 rivets are used for those. After I finished the last 3-3.5 rivet I could reach on the other ribs, I reset the squeezer for the 3-4 rivets on the splice rib. I went ahead with all the rivets on the splice rib since I didn't want to continuously switch between the squeezer for the splice rib and rivet gun for the other ribs.

The three forward-most rivets were the most difficult to set. Those holes are on individual tabs due to the leading edge curvature, so the fluting done earlier really doesn't help align these holes. I had to work each of the holes into place with a pick before I could insert a rivet. The other challenge with the forward-most holes is the awkward riveting position. You need long arms if you're riveting by yourself, and the holes essentially point up when the leading edge is in the cradle. I mitigated the second issue by rotating the cradle back toward the bottom a bit, and using scotch tape to hold the rivets in place. There isn't much you can do about the long-arm problem if you don't have a rivet partner handy, and I have the bruises on my bucking bar arm to prove it! The forward rivets ultimately went in successfully even though it took some extra time and effort to get them in place.

The final riveting task is inserting the landing light mount bracket and the top J-Channel. Both parts have good access with the rivet gun, and went in without any problems. The mount bracket has a definite top and bottom, although that isn't explicitly called out in the plans. The hole for the light is clearly offset, and you can see the offset in the plan drawings if you look closely. When the bracket is in place, the hole should be offset toward the bottom of the leading edge to align with the landing light cutouts.
[3x Rivet Gun, Back Rivet Set, Back Rivet Plate, Swivel Mushroom Set, Tungsten Bucking Bar, Pneumatic Squeezer with 3” Yoke and Flat Squeezer Set]