I’m getting very close to start sealing.  I say that in every post, I think.  Seems like I keep discovering more things that need to be done. That being said, I am getting rather close.  If I get a fair amount done tomorrow, I may be able to deburr and dimple this week… which could set me up to start sealing next weekend.  School in the evenings, and on Saturdays is really slowing me down!  I really want to be done with the tanks, as I’m falling behind my timeline goals…

The first task of the night was to use my new fly cutter to cut out the access plate holes.  This was a bit of a chore with my crap-tacular harbor freight drill press.  Fortunately, the end result was exactly what I wanted. 

Here are the flop tubes I purchased.  Most people only do one flop tube if they plan to do inverted flight, but that means that I’d have to remember to select the correct tank.  By installing two flop tubes, I don’t need to remember to select a particular tank.  On the other side, there are reports that the flop tubes will wear out and need replacing.  We’ll have to cross that bridge when we come to it….  Apparently the flop tubes enter through the front of the tank.  The diagrams are not the best, and the instructions flat out don’t even mention the installation of flop tubes…. so I guess I need to do some research before I tackle this. 

Here is the circle cutter’s end result. At this point, I skipped ahead. For some reason I just didn’t feel like messing with nut plates.  I’ve got to knock out these access plates, the vent routing, and fuel sender wiring.  

Next up was match drilling the deluxe fuel caps and flanges I bought.  I used a blue line from the fore and aft rivets to help with alignment.  Easy day. 

Tada… I knocked out both tanks’ fuel caps.

I still need to countersink the flange to accept the dimples in the skin.  Next time. 

I also match drilled the fuel drains.  Instructions say they need to be countersunk, but that has already been completed.Finally, I didn’t take a picture, but I also made the little fuel vent holders that attach to the cap flange out of scrap.

Tonight I finished the two z-brackets that had to be re-done and installed the nut plates that I was missing. 

The spar was fairly easy to countersink for the nut plate rivets, however the outboard rivets have to be done without a countersink cage.  Use a sloooow drill and its a piece of cake.

Unfortunately I cannot say the same thing for these rivets.  I had a heck of a time getting these rivets done and it took me way longer than I wanted.

I also drilled and affixed the nut plates to the capacitive fuel sender plates. 

Finally, a day in the shop where I left feeling like things are moving along and a lot was accomplished and I was much better about taking pictures today.

Today I started by machine countersinking the tank skins to fit the baffles.  These need to be countersunk instead of dimpled in order to allow the baffle to be easily installed and sealed.  It takes time to countersink all of those holes, as its an easy way to really mess up the skin.  

Here’s a good close up of the countersinking in progress. 

After machine countersinking was done, I disassembled the tanks and labeled all the parts.  I then turned my attention to the tank attachment angles and reinforcement plates.  I realized when I looked at the plans, that I had forgotten to trim off the excess (more than 2″) on the reinforcement plates, so that was the first task.

Next, I clamped the angles in place and drilled the three parts for rivets. 

Now after doing this,  I’m pretty sure the reinforcement angle should be higher up to help seal the tank, but its too late now, so I’ll have to cross that bridge when I come to it.  Worst case scenario, I have plenty of scrap and can fabricate a replacement quickly. 

Time to move on to the capacitance fuel sensor I purchased.  Each tank has two plates that need to be installed and isolated from the structure.  I match drilled all four plates. 

I made the stiffeners ahead of time, but skipped final drilling them when the instructions called for it.  This was a good call.  I was able to trim the fuel sensor plates to fit the stiffeners at the same time as I did the final drilling.  Saved me a step or two. There is still a lot to do for the tanks before I can start sealing them up.  Next time I will try to compete the fuel sensor and access plates. As a side note, I bought a fly cutter on Amazon for $10.99.  It arrived today and here is a picture.  It can cut holes with diameters up to 6 inches.