Fuel Tanks

[Edwin Otha]

These seem to be working just fine, All I need is the knob.

EO

[astjp2]

Ed, have ACS build you the knobs, they have a shop in Arizona and may do custom work. Tim

[Edwin Otha]

Thanks Tim,
I was hoping to find one before I started making them. Thanks again.

EO

[Hank Jarrett]

A really great way to find tank leaks is with a Condom (OK, quit laughing). One of the big risks looking for leaks is you can EASILY damage the tank with pressure. Using air will find smaller "weeping" leaks much easier than using a liquid. All you do is put a condom over one outlet, plug all others except the one you are going to put the air in and then plug that one after putting the air in. You will NOT need a compressor. I just blew into the fuel line to inflate the condom. If it stays inflated, you are golden! If not just put some dish washing soap and water in a sprayer and you will get bubbles where the air is getting out. There are two really fun parts to this process. One is the look on peoples faces when they go past your hangar. The second is trying to convince the pharmacist why you are buying the cheapest condom he sells. Not sure which is more fun. ;-)

[Scott]

My aux tank was leaking at the outlet fitting weld, and a couple of pinholes in random locations on the bottom skin caused by localized corrosion.

I remember thinking it could have easily been fixed in situ using sloshing compound. It renders the tank likely unweldable, but it's a viable fix assuming your wing has otherwise life left. There are different techniques depending on whether your trying to seal the whole tank or just the botom, and best if you're able to remove the outlet fitting/screen, but not nessesary if you're careful.

These day you have the advantage of inexpensive usb cameras that'll fit in the tank, even through the drain fitting boss, so you can see what you're doing.

If you're able to pinpoint the location of the leak, you could apply proseal internally with a brush attached to a bendable rod through the filler neck or, if you have or can create access externally clean and brush proseal on the outside. Note, brushes with the bristles shortened by half or two thirds work better for proseal.

not somerhing i would do with the tank on the bench, but if you're wing is in good condition, it's worth a look.
S

[Robert Lees]

...you could apply proseal internally with a brush attached to a bendable rod through the filler neck or, ....

Proseal is good stuff, but you need a clean surface to start with (and as Scott implies, it is not a "sloshing compound"). It is what tens of thousands of RV builders are required to use to seal the integral fuel tanks on the RV they are building (but they have fresh, new aluminium upon which to apply it. We are looking at re-sealing >70 year old tanks don't have the same luxury.

I did use Proseal to re-seal a >40 year-old Rockwell Commander wing tank the other day, but I did so without offering the owner any guarantees. I had to remove a whole bunch of previous historical internal and external attempts at sealing the leak first, but it worked!

Having a good illuminated boroscope was a great help.

Rob

[Scott]

Thanks for the clarification... two separate paragraphs discussing two different methods each using a different type of sealant.

The advantage of dealing with an aluminium tank versus resealiing a "wet" wing is that there's a high probability the tank has never had any sealant applied, plus the solvent environment ( gasoline) means the internal surfaces are lkely pretty clean. A wipe or brush with mek is all that's needed for internal application, mek and scotchbrite for external.

While a repair like this can outlast the tank, again, I view this as a stopgap measure to avoid opening up an otherwise good wing, but still get the benefit of your wing tank.