Wings, Fuel Tanks (Part 32)

After completing all of the Left Fuel Tank fitting during the last session, today I installed the Fuel Tank for the final time.  Each Fuel Tank is held on to the Wing/Spar by 18 AN3-4A bolts, 3 AN3-5A bolts, and ‘77 AN509-8R8 screws as shown in the plans excerpt below.

Here is the actual bolts that will be used for the installation.  The three AN3-5A bolts are on the far right....the rest are the AN3-4A bolts.  I installed these bolts through the Spar FIRST, and then installed the screws.  Might not make that much of a difference, but I think the bolts would “pull” the tank flush against the Wing Spar.  For corrosion resistance purposes, I previously primed the Wing Spar during Section 13.  As a result, there is already a “layer” of primer between the Wing Spar and the bolt washer.

Pictured below are the three AN-3-5A bolts attaching the Fuel Tank on the inboard side of the Wing.

Here are a few examples of the AN3-4A bolt locations taken from the Access Panel locations on bottom of the Left Wing.  At the top of each of the pictures, you can also see the installed AN509-8R8 screws and nutplates that attach the Fuel Tank to the Main Wing Spar.  

Since the screws being installed are steel and the skin is aluminum.....corrosion because of the dissimilar metals. To add some level of corrosion protection, I will use a paint brush to brush Akzo Primer on the screw holes and install the screws “wet”.


Here is the primer brushed on.....


.....and a screw being installed.  After the screw was properly set, I used a rag with MEK to remove the excess primer (screw on the left).  This will all get painted over later when the whole airplane is painted, but putting some primer between he screw and skin made me feel better.

After all of the screws had been installed, the Left Wing was put back in the wing cradle until the next step.