1.2 Hours -
Not being able to put it off any longer, it’s time to start riveting the ribs into the right fuel tank. Unfortunately, I only had time to finish one rib this afternoon. However, this gave me a good taste of the process.
I’ve opted to rivet and seal the ribs according to the instructions. Basically, cleco all the ribs into the tank skin, remove a single rib, apply sealant, replace it, rivet it, and, finally, apply a filet of sealant and encapsulated the rivet shop heads. The other option for doing this is called fay sealing. With this method, sealant is applied to each rib as they are clecoed into the skin. The filets are also created after everything is clecoed. The entire assembly then sits for a day or more before it is riveted. During riveting, a dab of sealant is placed into each dimple before the rivet is inserted. After riveting, the shop head are encapsulated in sealant. Depending on how the Van’s method works, I may switch to the fay sealing method for a few ribs.
I started with the second most outboard rib. After mixing some sealant, I smeared some on the flange of the rib, all the way around. Then, I clecoed the rib back into place, using clecoes in every hole, and then removed the outboard rib to allow better access to the rib I was working on. I then spent a couple of minutes trying to figure out the best way to orient the tank for riveting…eventually, I laid it on its side and used some duct tape to make sure the tank didn’t slide out of the cradle.
Riveting this first rib started off slow, but I eventually picked up the pace. I started on the bottom side of the tank and worked forward to aft. With sealant sticking to the rivets, seeing the shop heads was sometimes challenging, so using my rivet gauge was crucial until I got a feel for how many hits from the rivet gun were needed to set each rivet to the proper depth. The only other challenging parts of the bottom side of the rib were the two rivets that lined up with the stiffeners. Here, I had to use a very small surface on my bucking bar in order to reach the rivet around the stiffener flange.
After the bottom rivets were driven, I encapsulated the shop heads with sealant, and then flipped the tank over so that I could work on the upper surface. These rivets went a little more quickly. After they were set, I encapsulated them and then started working on making a filet of sealant between the rib and the skin. Once I was done, I did a little clean up on the outside of the skin. Now, all I can do is start working on the rest of the ribs and hope I’m getting them sealed well. Unfortunately, there’s no way to know that this is working until the tank is fully assembled and leak tested.
The facotry heads on my first tank rib look great!
The outboard face of the rib after riveting, encapsulating the shop heads, and making a filet of tank sealant along the edge.
A closer view of the rivet head encapsulation. After I looked at this picture, I had to run back out to the garage to fix the encapsulation on the left-most rivet where a small gap in the sealant can be seen.
I wasn't sure how much sealant to place in the nose area where no rivets are present. Hopefully, I've blocked any paths for fuel to get to the forward most rivets.
A filet of sealant is placed on the inboard face of the rib as well. I was starting to run out of sealant by this point.
