Fuel Tank Help

[Vandy12]

Hello all - Looking to a little advice here. 

Anyone ever opened the strake fuel tanks on a completed VEZ (or anything)?  My refurb project has some small foam debris contaminating the mains.  I got most all of it out with a rigged up vacuum nozzle and a borescope run through the filler neck, but am second-guessing the completeness of that method.  I'm thinking of cutting a fairly decent sized hole in the top of the strake to access the innards of the tank and thoroughly clean and re-seal if necessary.

Also, has anyone added the Saf-Air drain valves to a closed out tank?  I have the CP plans change, and it looks straighforward enough, but would like any hints/tips from those who have been there.

Thanks!

[MikeD]

Brian,

I had to open the strake on  Long-Ez to find and repair a leak after a pressure testing failure. The following is a very brief overview and tips of how I done this:

1. Make sure you are familiar with the internal layout
2. Decide which part(s) of the tank you need to access
3. Measure and mark out where you need to access leaving at least a 2 inch gap between your cut line and any internal bulkheads
4. Complete Number 1 and 2 again
5. Complete Number 3 again ..twice.
6. Using a suitable tool (I used a Fein Tool) cut along the lines BUT angle at 45 degrees so the inside of the final cut is smaller than the outside.
    This is very important when you come to closing the access hole

7. Lightly sand the glass/foam/glass edge of the strake and the removed section
8. Seal the glass/foam/glass with a slightly wet mixture of Flox
9. When the sealed edges are dry, lightly sand again and test fit the repair (allowing for a thin layer of flox to secure the repair)
10. Pressure test.

I hope this helps a little.

Regards

MikeD (U.K.)

[timdoell]

I would not cut holes in strake unless u have a fuel leak. Opens a whole can of worms. If you are worried about debris, fill tank with fuel and bypass boost pump back to tank filler hole and run for a while, periodically cleaning gascolater.  Fill tank half full, foam debris floats and can be skimmed off

[Vandy12]

Thanks for the advice gents.

I will certainly try to exhaust all options before getting any cutting tools close to the plane.  I DO, however, still have to install the drains on the front underside of the strakes so that ought to be fun.

I'll reply and update when complete...

Brian

[go ez]

I agree about not cutting the tank strake. Asking for trouble un-necessarily.

I used water rather than fuel to flush out the debris - more plentiful, gives ability to use a hose to let it continually gush out the filler cap, cheaper, less dangerous and the contaminant stuff floats better.

Retrofit drains - use at least 1/8" thick  aluminium insert - better 3/32" or 1/4" if you have room - ie more threads to provide seal.
Grind away the outer skin and foam but don't break into  the inner skin.
Gently rough up the inner skin to avoid de-lamination with the foam, drill-dimple the surfaces of the insert for torque resistance, make it square (with smooth corners/edges) rather than round for the same reason.
Drill & tap it before fitting and plug the threaded hole flush with candle wax.
Clean it then sand it epoxy wet with epoxy wetted paper to get a good non-oxidising bond to the aluminium. Fit it epoxy wet with plenty of flox and then fit the  outer skin in one operation.

When cured, lightly drill a pilot hole say 1/8" dia through the skins and insert, then very gently open out the hole with a hand file - this avoids risking de-laminating the inner skin from the insert which is a risk if you just drill right through.
Don't over tighten the drain valve - use weak threadlock like Loctite 243 to fuel seal it and lock it in place.

And when you start flying !!!! - every couple of hours check the tank screens visually when nose down, check the gascolator screen & bowl and the  carb finger strainer  until the contamination disappears

[Vandy12]

Awesome step-by-step - THANKS!