Riveting the Wing Skin page 1

July 18, 2010

Before we get started riveting the wing bottom skin on, please take some time to read the following webpage about proper rivet lengths, types and techniques. Don't skip this part, the information is important. When you are done, hit the "back" button on your browser to return to this page:
Mil-Spec for Rivets

Ok, now that we have finished up the Wing Assembly  we can go ahead and close up the wing. All of the holes have been already drilled, deburred and dimpled for you. You will need a bunch of flush rivets (AN426AD3-3) and some (AN426AD4-4) for the double rivet rows at the skin overlap on the short skin, aft of the fuel tank bay.

Here are my tools of choice for riveting. This rivet gun and these 3 bucking bars have built 2 airplanes, an RV-6A and a Bearhawk:

The rivet gun is a 3x rivet gun (not air-hammer). The flush rivet set attached to the gun is a swivel type with a rubber cushion to prevent slipping. With this rivet set you can turn out nice, dent free riveted skins consistently. The bucking bar in the middle is the one I use for most rivets.  It fits my hand well and is easy to control. The one on the left is the one I use when there is an obstruction (like the rib stiffeners) blocking the rivet.  The one on the right is the long reach one when my arm won't quite reach the rivet with my main bucking bar.

Before beginning, you will need to remove the plastic that is attached to the bottom skin. If you wish to remove the plastic in strips just exposing the rivet holes, use a soldering iron with a point on it to melt a line in the plastic. Note how the soldering iron is tilted back to prevent scratching the aluminum skin. A light touch is required to prevent scratches:

After the plastic is peeled off:

The plastic between the rows is left in place for now to prevent scratches in the skin.

Riveting is usually two-person job, especially in this case.  One person reaches underneath the skin to buck the rivets and the other one runs the rivet gun.

When you roll the skin back to reach underneath, be careful to not kink it. The rivets being used here are the flush 3-3 rivets.  These don't require much of a rivet gun burst, about 1 to 1.5 seconds usually sets the rivet just fine. Note in the above picture how Lonnie is holding the rivet gun.  His left hand holds the rivet set to prevent it from sliding around and the gun is held perpendicular to the skin to prevent dents.

We started with the rivets closest to the main spar. Drive only about 4 or 5 rivets in each row, working across the wing. Once you've done the first 4 or 5 in every row, go back and do the next 4 or 5 in every row, gradually working your back toward the rear spar. Once you get to a certain point, you will no longer be able to roll the skin back to get you arm underneath for bucking the rivets. At that point, reach in through the rear spar lightening holes or through the tip rib or through inspection holes depending on location.

DO NOT DRIVE THE RIVETS IN THE REAR SPAR YET!!! We need to do some more work before we drive those.

Awe - nice, smooth dent-free rivets; Its a beautiful thing:

On the short skin aft of the fuel tank bay, the skin overlap areas have a double row of rivets and these are the larger (size 4) flush rivets. We used 4-4:

When driving these you need a touch more air pressure on the rivet gun and little longer trigger pull (about 2 to 2.5 seconds).

Here we are at this point, all riveted up with the exception of the rear spar rivets:

Lonnie is my father-in-law and build partner who has helped me build 2 other airplanes; this one is the third. He is 75 years old but keeps on going. He was pretty tired after this 4 hour session of riveting.

Now we can go ahead and rivet the skin stiffener in place in the flap area of the wing. Here it is clecoed in place ready for riveting:

Click here to go to Riveting the Wing Skin page 2