[bmellis11]

I'm getting ready to install the rear baffles on my fuel tanks and that got me to wondering about how common fuel tank leaks are and when they are discovered. I know some builders have leaks at different times, so if you fall into this category, please just choose the answer for when you discovered a leak for the first time. If you've built multiple planes and had more than one of them leak then I'll leave it to you to choose which project to focus on.

 

[bruceh]

All of the above.

 

[FORANE]

Does bubbles under paint at rivets on the fuel tanks qualify as a leak?

 

[airguy]

Does bubbles under paint at rivets on the fuel tanks qualify as a leak?

Depends on who you ask - belongs under the "never ending" thread. Lots of reports, no real trail as to WTF is going on there.

 

[gmcjetpilot]

You can make leak free tanks. But leaks or seeping at some location is not uncommon. After 10 years the drain valve fitting started to seep, blue dye tell tale. Removed min paint around fitting. Fillet sealed around fitting. Touch up paint of sealant leak fixed.

 

[Majorpayne317641]

I had my rear baffle let go on one side after 12 years.

 

[Webb]

I’m surprised that there isn’t a welded tank or one with a fuel cell on the market.

 

[Snowflake]

Does bubbles under paint at rivets on the fuel tanks qualify as a leak?

If the bubbles are caused by fuel, then yes, that's a leak. It just hasn't come through the paint yet.

 

[abwaldal@gmail.com]

If the bubbles are caused by fuel, then yes, that's a leak. It just hasn't come through the paint yet.

I built new tanks for my RV-6A a couple years ago and balloon tested perfect. Installed, no visible leaks for a couple months then I wrapped some vinyl details on the wings. I use Costco premium fuel. I have no stains or leaks anywhere
BUT, I have a number (16) of rivets causing the vinyl to bubble up in numerous areas. some are 1/4" and a couple are 1" in diameter. Don't get any bigger or go away. Pop the bubble and nothing is in there.
The other rivets that are not vinyl covered show no signs of leakage.
Vapors are getting through the sealer and paint somehow. Paint is not bubbling up.
I intend to Green Locktite the little suckers some day.
My luck varies FIXIT

 

[Ironflight]

I’m surprised that there isn’t a welded tank or one with a fuel cell on the market.

We’ve got welded tanks on our Tundra (drop-in‘s from the top, with a cover over them, behind the spar - so not like an RV) and have so many cracked welds leading to huge leaks that we won;t take the airplane into the backcountry anymore….so I’m not a huge fan of welded tanks in lightweight aluminum applications……

 

[Ralph Inkster]

Dang! I think I will have to do this survey 6 times to fit my experiences...

Qualification - the first 3 planes I've built, leak free (over 2000 hrs total between them), later planes, a corner leak in one & a sender leak in another. Many other customer tanks repaired or rebuilt for a host of reasons, including one tank that had the rear baffle with NO Proseal on one of it's flanges at all!

I truely believe that RV tanks are an eventual Maintenance issue - either sooner or later (even my first leak free tanks) - accept the inevitable!

 

[bmellis11]

I truely believe that RV tanks are an eventual Maintenance issue - either sooner or later (even my first leak free tanks) - accept the inevitable!

Sounds like the same problem that Mooney owners have, though I think their tanks are harder to work on. I know a lot of them switch over to bladders. I wonder if anyone has ever used bladders on an RV.

 

[MikeinPhoenix]

I'm getting ready for my first attempt at repairing tank leaks in my RV-9A. Are there any good videos or instructions I could utilize to prep myself? I've found tank construction videos on YouTube, but nothing which focuses on repairing tank leaks. Thanks!

 

[guccidude1]

I'm getting ready for my first attempt at repairing tank leaks in my RV-9A. Are there any good videos or instructions I could utilize to prep myself? I've found tank construction videos on YouTube, but nothing which focuses on repairing tank leaks. Thanks!

Where is the leak? Dan

 

[Ralph Inkster]

I wonder if anyone has ever used bladders on an RV.

RV tanks are a series of cells with full ribs in between, would require major re-engineering the tanks with different shaped ribs & rear baffle, essentially totally re-designing the tanks & get unique bladders fabricated for them.
A huge cost compared to a bit of Proseal, getting dirty & time.

 

[MikeinPhoenix]

Where is the leak? Dan

I haven’t opened up the tank yet, but it appears to be leaking around the fuel sensor flange and possibly along the most inboard aft edge of the fuel tank. I’m planning to remove the flange and use a boroscope to inspect the inboard aft area.

 

[Majorpayne317641]

The vans repair kits work if you need to go into other baffles. If it’s the sender baffle then that sender plate is enough room to work on that area. Go to HF and buy a mechanics mirror set and a good battery powered work light. I used the proseal remover that costs an arm and leg at ACS.

Slowly work the flange free it will be a huge pain if they used proseal (but that’s better then a leaking cork seal). Once you get it off remove all the old gunk on the flange with said remover.

I made a thick fillet over the existing proseal on the inside of the tank. I did clean it and scuff it before the new proseal. Mixing thoroughly to make sure you have a consistent proseal is also important. This is not hard but it takes time and patience.

If you didn’t build the plane and you have a RV-8 don’t forget the Z brackets behind the tanks on the inspection plate side of the wing spar. Those are really fun to unscrew. HF short ratcheting 1/4 mini ratchet was the best option I found after much trial and error.