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Fixing the Tank

September 8, 2012

After some research and pondering I came to the decision that I was going to cut holes in the baffle and repair the tank that way.  The research I did came up with quite a few ideas on how to fix a leak without actually opening the baffle.  I felt like all these options were just temporary.  Some were just ridiculously complex, requiring a vacuum pump and diluted proseal.  One post, however, clarified things for me.  The person had a similar situation as me.  He had several leaking rivets along the baffle as well.  He chose to open the bay that had the leak and was so surprised by the poor bead created by the proseal that he opened up all the bays and repaired the bead on them all.  This seemed like a good idea.  I have to open 3 of the bays anyway, so I might as well do them all.  I am really glad that I made that decision.

If you are reading this and are suffering with the decision let me tell you what I found.  The proseal didn’t form a good bead at all.  I found that it was so thin is many places that I cant figure out why more rivets aren’t leaking.  Opening the baffle in all the bays is easy.  Once I made up my mind to do it, it took no time at all.  If nothing else it is worth the piece of mind knowing that that baffle will NOT leak.

I have several steps to do and here is what they are:

  1. Mark the center of the baffle and scribe a 4″ circle
  2. Drill a #40 pilot hole in the center of each mark.
  3. Setup the circle cutter
  4. Cut the holes
  5. Clean the holes and make them smooth and safe
  6. Identify some .032″ material in my scrap pile and mark out 5.25″ circles on it.
  7. Cut the circles out with the band saw
  8. Clean up the edges of the cover plates

How did I arrive at a 4″ hole?  I need a hole that I can reach into and get all the way to my elbow through.  4″ seems to fit the bill nicely.

As you may remember from a previous post I had already used all of my proseal, so I had to order two of the “syringes” of proseal from Vans last week.  I also ordered about 45 each of two types of blind rivet.  I am planning on 8 rivets / cover plate to attach them to the tank.

Now its time to get to work.  I have lots of pictures and even a few videos for you.

I started out marking my center on the baffle and cutting the holes.  Here are a few videos on me using the hole cutter that I hate so much.

After this I spent a bit of time cleaning those edges up and getting them smooth and safe.  Once that was done it was time to cut out the cover plates that would eventually seal the holes shut.

I was lucky here.  On my other fuel tank I had messed up the rear baffle and needed replace it.  This means that I had another baffle in my scrap pile that could use to make the cover plates.

Now I have my marks I have to cut the covers.  I decided to use my band saw for this.  The hole cutter that I used in the previous task wouldn’t work because it makes a pilot hole in the center of the circle.  So I plan to rough out the circle on the band saw and finish it using a file and the scotch brite wheel.

Next on the agenda I have to make a mark for my 5.25″ circle.  I need a compass, which I didn’t have and had to make an “emergency” trip to Lowes to get.

Using the band saw, now Im going to cut out the circles.  I need to take as much aluminum off as I can.  Anything I leave on is aluminum I will have to file off later.

So now I do that 5 times and I get my rough covers.  The rest of the work is just trimming, filing and grinding away the edges.

Do that 4 more times and you get all the cover plates.

I would say that all of this took about 4-hours, including stopping for lunch.  It was really a pretty easy.  As usual it took more time deciding what to do than it did to just go do it.

After I got the holes cut in and cleaned up I got out my inspection mirror and flashlight to take a look at the proseal joint.  I was really suprised.  The bead was just dreadful.  Like Dan Horton said in his post on VAF the bead was just anemic. I am really glad I went to this added effort to fix it.  I am so glad that I am contemplating doing it to the other tank, even though it didn’t show any signs of a leak.   I have time to worry about that later.

I’ll try to get the prosealing done today.  We’re going to be driving down to Little Rock tomorrow for an airshow.  The Blue Angels are performing and that is always worth the drive.

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