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SERVICE BULLETIN 13-12-19 Fuel Tank Attach Modification

Piper J3

Well Known Member
I acquired an older factory-built fuel tank that has never been used. I am in the process of doing the latest SB and have decided to remove the tank lid to make the job easier and more thorough. So far I have removed all the rivets for the strengthening plates and also all the rivets on the tank lid. I have tried using a single edge safety razor blade to slice thru the Pro-Seal on the lid flange and I’m finding this to more difficult than I had imagined. Does anyone have a suggestion on how to lift the lid off the tank? Does Pro-Seal soften with heat from a hot air tool?
 
A little heat probably can't hurt any. I found it easier to use a utility knife so I had a handle with which to get some leverage. Taking the lid off is a good call... it's much easier to do the modifications that way. Just be careful about the vent line.
 
Here's how I done it ;)

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No heat needed, just use a couple of thin knives.
 
In my original post I stated that I tried to use a single-edge safety razor blade to slice thru the Pro-Seal on the tank lid. I liked the idea of using the thin blade so as not to distort any aluminum, so rather than slicing I now lightly tap the razor blade with a hammer straight through the Pro-Seal joint. The razor blade spans 1-1/2 rivets on the tank lid, which makes it easy to index the razor to the next position. The blade is taped in until the back safety edge meets the tank lid. A pliers is used to pull the razor back out. No twisting or prying is required.

I only mention this technique as a reference in case there is ever a need to peer into the bowels of the tank sometime in the future.
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I bought some of that when I pulled my tank apart. It works, more or less, but if I were doing it again I don't know that I would bother with it. I can probably scrape sealant off quicker and with less mess. It would be more useful on dimpled parts, I'm sure.
 
My 2 cents worth - -

I have done multiple tank updates and have found a flexible blade putty knife and a hammer will take a top off in 10 minutes. I then use a wire cup on an angle grinder to quickly clean old sealant off. You have to be careful how you do the wire brush, but works fast.
 
I have done multiple tank updates and have found a flexible blade putty knife and a hammer will take a top off in 10 minutes. I then use a wire cup on an angle grinder to quickly clean old sealant off. You have to be careful how you do the wire brush, but works fast.

Ditto. Get a couple of putty knives and go at it!
 
Try craft sticks

I had to pull a rib out leading edge and found that once I got the separation started I could use a craft stick (tongue depressor) in the crack and use it to propagate the separation and occasionally using a razor blade in the gap to cut. MEK also softens the pro-seal and cleans up the residual. Wear thick rubber gloves with the MEK (methyl ethyl ketone), it is not your friend on your skin and use in a well ventilated area per MSDS.
 
Ready to re-seal

I have removed tank lid and large fuel sender plate and have cleaned all the mating surfaces. Likewise, I have cleaned and mated the two tank strengthening backup plates. Rivets and screws have all been trial fitted and I have sufficient clecos on hand. I also have rubber gloves, acetone, paper towels, Popsicle sticks, and cell phone in case of emergency. So I?m working up my nerve to mix my Chemseal B2 that is in a 3-1/2 oz. mixing/dispensing tube. I?ve been watching YouTube videos and I?m undecided how to proceed.

I could do this two ways?.

Option #1 Mix entire tube with hand plunger and then use a wooden plug to force the sealant out thru the provided nozzle. Chemseal is fresh and B2 formulation has a 2-hour open time. I think I can install both strengthening plates, then the top plate, and finally the fuel sender plate within the 2-hour allotted time.

Advantages

Assured correct mix ratio and complete mixing
Dispense nozzle should be better than Popsicle sticks

Disadvantage

Need to mix entire tube
Requires hand mixing within the tube

Questions

When mixed will I be able to push material thru nozzle with a wooden plug?
Will I be able to control the bead when pushing by hand?
Will bead dispense shut off when I stop pushing wooden plunger?


Option #2 Somehow cut the tube open and maybe mix three smaller batches to do the job with less time constraint. I have digital gram scale to weigh both components for correct mix ratio.

Advantages

More time to complete job

Disadvantages

Makes a mess
Need to use Popsicle sticks instead of nozzle ? smear instead of bead

Questions

How to cut Chemseal tube open to get to component parts?
How big of a mess am I really going to have?

I?m leaning toward doing the entire job in one sitting. I?d be interested in hearing how others accomplished this?
 
I didn't use the little tube. I have the quart can and mixed up a small batch to do everything but the top and sender/access plate, then later on mixed a larger batch to do those. If you have everything prepped and have a plan, you could probably get it all done in under two hours. It also takes longer to set up and cure if it's cold where you're working.

That said... if you mix the whole thing up, you can put what you don't use immediately in a deep freeze and it will keep for - well, I don't know how long. I saved a little of my second batch in a syringe and put it in the deep freeze. I used some a couple of weeks after mixing it (when I found a small seep) and it was fine. Thaw it out, use what you need, pop it back in the freezer.

That stuff can make a king sized mess. I wouldn't want to try cutting the tube open, sounds like a great way to end up with sealant goo everywhere.
 
How deep a freeze

I recall reading that the builder that worked at Gulfstream said they mix up a whole airplane worth and deep freeze it and pull it out to thaw as the job proceeds.

So now I am in leak fix mode on my tanks and don't need a whole tube. Just a repair and wait quantity. Will the drawer freezer in the house ( chemseal tube in a ziploc bag to stay out of trouble ) do the trick? And how long does it take to thaw?
 
I recall reading that the builder that worked at Gulfstream said they mix up a whole airplane worth and deep freeze it and pull it out to thaw as the job proceeds.

So now I am in leak fix mode on my tanks and don't need a whole tube. Just a repair and wait quantity. Will the drawer freezer in the house ( chemseal tube in a ziploc bag to stay out of trouble ) do the trick? And how long does it take to thaw?
Though there are different brands/mixtures, If I recall well, the folks at SealPak (now closed) told me it was about -40f and even at that temperature it was only good for a limited time. No, the home freezer is insufficient to hold off the curing process.
 
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