Today was the big day for the finishing the first fuel tank.  All that was left for the right fuel tank was to seal and rivet the rear baffle plate.  This will only take an hour or two at the max...  WRONG!!!

After some contemplation, I decided to prime the z-brackets with the exception of the flange that gets sealed and riveted to the fuel tank.  To keep the primer off of the z-bracket flange, I masked the z-bracket with some Scotch 35 vinyl electrical tape.

Prior to mixing up tank sealant, I decided that it was finally time to subject my $5 Harbor Freight blind rivet puller to the ferocity of the scotchbrite wheels on the bench grinder.  My rivet holes for the z-brackets are pretty close to the "web" of the z-bracket so pulling those blind rivets was going to be a challenge.

This is a cheap rivet gun and it shows when going to pull rivets with it.

Here is another picture of the down right tool abuse at the hands of the bench grinder.  This thing only has to pull a handful of rivets on the tanks and leading edge.  I hope it survives long enough to get the job done.

I wished that I had the time to take some pictures of the tank sealing process just to better show how messy this job can be.  Anyway, we are down to crunch time.  This is where it all comes together.  After sealing the rear baffle plate, if I have forgotten anything inside the tank, I will no longer be able to correct the problem (easily anyway).  Therefore, I gave the tank one more last look over and inspected all the ribs, shop heads, etc.  I made sure that the vent line sat securely in the vent clip by the fuel filler neck.  I checked the capacitance sender connections and that the wires were secured to the vent line with sealant.  I checked all fittings for tightness...  You get the idea.

I spent probably an hour getting everything ready.  Kind of kept a checklist of things to do in my head:

• Read other builders web pages on sealing the tank baffle to get everything straight
• Cranked the air conditioner in the garage down to 65 to start cooling the garage down. 
  • There has been some discussion on the Yahoo group about how quickly tank sealant starts to set-up.  One builder claimed to have as little as 45 minutes working time with the cartridge tank sealant at 80 degrees.  However, lowering the temperature of the room to 70 degrees and I have gotten nearly 1.5 hours of working time.
• Clean the blind rivets and solid rivets in MEK.
  • AN427AD3-3.5
  • 41-H (tank baffle skin to rib)
  • 42-H (z-bracket, tank baffle skin, to rib)
  • AN470AD4-4 (outboard z-brackets: baffle skin to rib)
  • AN470AD4-5 (outboard z-brackets: z-bracket, skin, to rib)
• Cleco pliers and cleco's
• Rags
• Last quart of MEK.
• Sealant gun and air hose.
• Sealant spatulas
• ONE ENTHUSIASTIC HELPER or WIFE (Which ever is easier to obtain).
• One chilled 6 oz cartridge of tank sealant.
• FORGOTTEN / MISSED ITEMS
  • Rivet hammer with universal rivet set.
  • Bucking bar

I used the sealant gun to place a bead of sealant along the rivet lines on the tank skin and rib flanges.  I used a spatula to smooth the bead of sealant out and make a nice smooth line of sealant.  Then the race was on.  Okay TAMI, put in cleco's.  I put cleco's in every hole on the rear baffle.  My thought process was that when the tank sealant is fresh, it flows pretty well around all the irregularities and cleco's pull the two components together.  I figured that clecoing every hole (like Van's tells you to do), that it would hopefully allow that tank sealant to flow better along the baffle plate flange.  THERE ARE A TON OF CLECO'S IN THIS THING.  Even with a helper, it took us a good 10+ minutes to get it all clecoed up.

Then came the use of the pneumatic squeezer.  I'm off squeezing at a frantic pace.  After about 10 rivets, I realize that this is going to take more than the 20 minutes it takes to rivet a rib.  I squeezed like crazy and it still took me just a hair over an hour to squeeze the tank skin to baffle rivets.  Tami cleaned cleco's as we went as that was a huge job cleaning up the mess.  It was good she did this early on as I needed her help at the end dabbing sealant over the rivet shop heads.

You are still not done by a long shot. 

I then started on the blind rivets for the z-brackets.  I stopped and did a double>>   No, I mean triple check on the orientation of the z-brackets.  If you you rivet them on backwards>>>  forget about ever getting this thing mounted to the main spar.  It would be a huge mess to fix.  When I was happy with orientation, I swirled the head of the blind rivet in sealant and put it in the hole.  I must have done something right as I didn't appear to have any alignment problems here.  After the 3rd z-bracket, my cheap-ass $5, ground-down rivet puller jammed and wouldn't release the pull shaft.  I ended up having to disassemble the rivet gun and retrieve the shaft.  Okay that KILLED 10 VALUABLE MINUTES>> CRAP...

Then came the outboard z-brackets.  They are NOT installed with blind rivets.  They use solid 470 rivets.  Okay, I will use the longeron yoke and the pneumatic squeezer>>>  NOT !!!!  TAMI> Stop cleaning cleco's?!?!?!?  Where is my rivet hammer and bucking bars?!?!?!?  Another 15 minutes and VOILA>>>>  The tank is riveted together.

I did not put a lot of excessive tank sealant on the rear baffle flange (not like I did with the rest of the tank anyway).  I just made sure I had a uniform bead of sealant about 1/2" wide or so.

All we had left to do is dab sealant on all the shop rivet heads and a little touch up work.  Use your helper here work on the opposite side of the tank you are on.  I had Tami make up another batch of sealant from the quart can (approx. 40 grams) to finish up.  Tami ran down one side of the tank with a spatula and I ran down the other.  It still took us another hour to finish this up. 

At the top and bottom of the outboard ribs, you have a notch that needs to get sealed up.  This is a relatively big opening.  I went kind of crazy with sealant here.  Looking at the tank the next morning, I think I am in pretty good shape here.

In my usual tank sealing fashion, I fully encapsulated the shop heads of the rivets.  Notice, my fillet is fairly small on the rear baffle.  I didn't want sealant to interfere with installation on the main spar.  I may beef this us a little, but I am going to wait until I see how the tank does on the pressure test.

I then did a visual inspection of all the rivets that were set tonight.  I noticed that the rivets on the top side of the tank were all flush and looked great.  The rivets on the bottom of the tank were not quit as flush.  The tank skin was countersunk at the same time with the same countersink cutter, but why the difference???  The only thing that I could think of is that I did set the rivets on the top side of the tank first.  This allowed the sealant under the factory head to flow better as it had not started setting up yet.  By the time I got to the bottom side rivets, the sealant was starting to setup and was holding the rivet heads up slightly.  The difference is ever so slight, but you can see it if you look really close or run your finger over it.  I will be happy IF IT DOESN"T LEAK !!!!!!!

Parting comments on tanks:

• TANKS SUCK !!!  Sealant gets everywhere.  If you touch sealant, everything you touch after that will have sealant on it.  I found sealant making it all the way into the house on the computer.  We toasted 4shirts, 2 pairs of shorts, and 1 pair of sweats during our sealing endeavors.  I ended up using almost 1 gallon of MEK to do the right tank alone.  MEK is not something I would voluntarily expose myself to if it wasn't for this project.  MEK is nasty...  Works great for cleaning up sealant, BUT.....
• If you are as lucky as I am to have your wife help you on the plane, don't expect her to be to happy (or willing) to work on sealing the fuel tank.  I had to darn near beg/grovel to get Tami out in the garage to help.  As soon as the last rivet was set, she was like the road runner sprinting out of the garage and into the house.  I would turn around and she would be GONE!!!  All I could see was the smoke from the soles of her tennis shoes!!!!!  Tonight, I told her we were done with tank sealing and she actually offered to come out and rivet skins on the wing (no groveling required)...  THAT's MORE LIKE IT.
• If you plan on using a sealant gun, do yourself a favor and order the quart can too.  Even when I used the sealant gun, I still always seemed to need to make up "just a little more " sealant.  On the right tank alone, I used two sealant cartridges and around 2/3's of a can of sealant.
• Work in a cool space.  10 degrees can make a big difference with the working time of the tank sealant.
• Van's claims you can seal a tank in 2 to 3 work sessions.  Whatever....  I probably have 6+ work sessions to get everything sealed.  Anyway you slice it, tanks are a ton of work.  I haven't pressure tested yet and I have almost 100 hours on this fuel tank.  I have seen some builders logs claiming to get their tank done in the neighborhood of 30 hours.  I don't know how they do it.  It probably wasn't their first tank.