speyers

speyers

Well Known Member
I am just about ready to put the rear baffling on my tanks and test them for leaks. I was thinking and wondering if I could test them before I but that real baffling on. Do you think it would work to put them in the craddle and just fill them up with water? My thinking is that I would be able to see if there are any leaks BEFORE putting on the rear baffle. Think it will work?

-David
RV-8
Wings almost done...
 
Nope.
It will always leak at the rear baffle...Murphy will have his way no matter how much you try to defeat him...
 
When you are finished with the tanks, put some masking tape over the fittings to keep the bugs out, put the cap on and set them aside for a week before doing any kind of testing. You want to make sure the proseal is fully cured before pressure testing. This will keep you from creating a leak with the air pressure.

(BTW, the masking tape will allow the tank to breathe as the temperature changes causing the pressure in the tank to change. Capping the tank and its fittings can cause the tank to expand and contract with changes in temperature, which could cause some deformation and possibly leaks. When installed, the tanks are open to the atmosphere.)
 
Dave,

In my opinion that plan would be a complete waste of time, proving nothing. Gross leaks are more likely to occur somewhere along the rear baffle. Besides, since fuel is less viscous than water, weeping rivets will not likely be discovered when subjected to a standing water test as it is unlikely water could seep through a tiny void through a rivet hole as easily as far less viscous 100LL is, especially under pressure.

While the back baffle is off, I recommend you recheck and make certain you have an unbroken fillet seal of tank sealant around every stiffener and every rib. No voids in that fillet seal are allowed. And while you are at it, verify that every rivet shop head is encapsulated with sealant. Doing these things will greatly minimize any chance for leaks.

ork092.jpg
 
Capacitance fuel senders?

If you have capacitance fuel senders installed, make sure you cover the inside of the BNC connector with pro-seal. I mean really cover it so no fuel gets to it. They tend to leak unless completely covered and sealed.

Did you get that? Make sure the BNC connector is covered. ;)
 
I did it

I did exactly that before I put the rear baffle on. I wanted to find any potential leaks around rivets or around the "nose" area of the end ribs before closing up the tank. Worked just fine. I did mine with the tank access plate off so the water only came up to the level of the edge of the access hole. I'm not sure I would fill it up all the way to the top without the baffle on since the water pressure might have a tendency to bow the skin out in the area normally supported by the baffle and unnaturally stress the aft ends of the tank ribs.

I would NOT consider this test final by any means! There has been some discussion that you could still have fuel leak through a spot that held water. I just figured that a water test would find major leaks and ANY test would reduce the probability of an unpleasant surprise later!

Of course you still need to test the tank in the normal way after the baffle is on. Good Luck!

speyers said:
<snip> Do you think it would work to put them in the craddle and just fill them up with water? My thinking is that I would be able to see if there are any leaks BEFORE putting on the rear baffle. Think it will work?</snip>

-David
RV-8
Wings almost done...
Click to expand...
 
Fuel Tank Leak test using Vinyl Wrap

Hello,
I am playing with vinyl wrap as prelude to (finally) upgrading my paint scheme from primer and bare aluminum. I have started a blog (of course) detailing my start to finish vinyl wrap adventure (rv8wrapup.blogspot.com) but have come across something I should pass on.

If you want to find fuel tank leaks, I mean the really tiny ones that do not leave a blue stain on your tank, place a strip of vinyl wrap (3M 1080 series) along the rivet line and leave it for a few days. It will peal off, at least mine did (test first on your plane if painted). Below is what you see over a leaking rivet. No balloons, dunking, soap, baying at the moon, etc; just a few gallons of fuel and vinyl wrap. You can use a 'big hole' paper punch to make vinyl wrap spots to place on each rivet to test for leaks which will minimize vinyl waste (it's expensive).

DSCN4258-640x480.jpg


This is a vinyl test strip on the outboard aft edge of (pilots view) right fuel tank. The leaking rivet is clearly visible. Assuming you have fuel in the tank.

It is a good test prior to painting as well.

If you are curious about vinyl wrap from the perspective of one who is clueless about it, then you might find my blog of some interest. Better yet, buy some small sections and 'play' with it like I am.

As for my leak? I have applied thread blocker green to rivet in hopes it will miraculously seal the leak because frankly, I really do not want to mess (again) with fuel tanks and pro seal.

Hope this helps.
VinceH
Desert Aire (M94)
Washington

RV8 N8432 - flying (well not at the moment...fuel tank leak)
 
I tested my tanks before the rear baffle went on with water and am glad I did. I had two stubborn rivets that produced one or two drops a day of seepage. Easy fix with the baffle off. I also had a seem between the front spar and skin that was big. Would have been impossible to fix with the baffle on. The culprit was a scrap of metal that didn't blow out while cleaning.
 
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