Group,
After over 11 years of building on a  Glass Goose, I may be finished. Not
finished in a good way,  though.  I filled my wing tanks several months
ago
and was  delighted to fire up my Renesis.  Today, a month later, I
noticed
the leading edge cap separating from the wing near the wing  root and
leaking
out of it.  With further investigation, I also  discovered leaks on the
bottom of the opposite wing at the shear  web.  The residue of the leaks
is
yellow-tan in color and  sticky.  My conclusion is that the alcohol in the
gas has had  an adverse affect on the epoxy.  I'll call the epoxy maker on
Monday to get his words.  I read about the effects of alcohol on epoxy  on
the internet several years ago but was assured that it wouldn't  affect a
tank that was Jeffcoed.  Sealing the tank is the least  of my concern.
What
makes me think the wings are now  unreliable is that the fuel has wicked
up
into many areas of the  wings' integrity so, at this time, I don't think I
can trust  them.  I offer this as a warning to those that can use it.  Do
any
of you have any ideas or words that can help save this poor  little
airplane.

Sandy McNabb
Renesis in a Glass Goose  (retired)


Sandy,
What kind of Epoxy did you use,  was it EZ Poxy? I am
assuming you jeffcoed the tank based on what  you wrote am I correct?

Does anyone know of any protection for  composite built aircraft for the
problem described here with alcohol  laden fuel or ethanol? FYI, fuel
bladders is not a workable solution  for most composite airplanes.

James Ealey

I am  interested in your reasons on why fuel bladders is not a
workable  solution for most composite airplanes. Are you speaking
of the blue  foam Rutan method?

Paul Lamar


Yes, the Rutan  designs are what I was referring to with the blue foam.
With these  designs unless you get specially made bladders and you are
will to  eat the weight penalty you will
definitely lose something that the  design offers in performance.

James Ealey

Auto  fuel is a 25% savings in fuel cost. I don't have a weight per square
foot yet on the McMaster neoprene nylon material but it can't be  much
at only .022 inches thick. I'll order $5 worth and weigh it and  do some
fuel tests on it.

Custom built was what I had  in mind for the fuel cells. One can hammer
ribs out of sheet steel  and use them to clamp and heat the joints.
I suspect something like  250 F will do the job.

It will take a bit of trial and error to  learn how.

Paul Lamar


James,

I have a wet wing  with fuel in the whole leading edge rib sections.  A
few
holes are cut in the lower rib to let the fuel flow.  The building plans
call for sealing the surface area of all of those D sections plus the
holes.
It is a daunting task and I doubt I can accomplish it with 100% certainty.
Worst get the outer skin is added later and those joints can't not be
properly sealed.  Since I am exploring using high ethanol content fuel,
I'll
be hiring someone to weld thin 0.3mm Teflon bladders for me.  With the
absence of JeffCo coating the weight increase will be nelgible.  I haven't
figured out the connection method between them yet.  Probably need some
male/female tube connections welded on.  Bladders can be designed to
collapse if desired.  Sandy, I wouldn't scrap the wings yet.  Chances are
the ethanol is reacting with the epoxy surface or remaining wax.  I don't
know which type of resin you used but some of the vinyl-esters are
specifically designed to hold solvents.  Chances are good you can drain
the
fuel heat up the wings to 25C and evaporate the remaining solvent out of
them.  If you are concerned with the integrity of the wings, make a jig
and
load test them with sand bags.  After passing that test you can make a
plan
to add bladders.  Water infiltrating into fuel tank depends a lot on the
tank material, vent air temp and humidity.  Naturally amphibs.  operate
in a
humid environment.  Having the wing tanks feed a low sump tank is also a
good idea.  Pump pick-ups should be at least a half a gallon volume above
the bottom of this tank.


Doug in Japan

Those big tanks in the  ground at the gas station are now vinyl ester. It
seems that tanks made of  vinyl ester or lined or doubled up with vinyl
ester
would do fine. Or if you  have a TIG machine, or better yet, a friend with
a TIG machine, repair the  damage with whatever epoxy you built with and
make up some nice aluminum  tanks. Or, race car fuel cells come in many
interesting shapes and sizes and  the smaller ones are cheap enough. You
can order
the bladder without the  steel can. Check out ATL
http://atlfuelcells.com/

  (http://atlfuelcells.com/)

and


http://www.buycheapr.com/us/result.jsp?ga=us3&q=racing+fuel+cells


http://www.buycheapr.com/us/result.jsp?ga=us3&q=racing+fuel+cells


Lynn E. Hanover


I think teflon is over kill.  I am not sure it is easy to weld.  Reliable
bonding is a problem.  Polyethelene is what most solvent bottles are made
from if they are not glass.  It is a well behaved thermoplastic and can be
welded.  Harbor Freight has soldering iron like tools for plastic welding;
hot gas jet. McMaster has poly sheet in the catalog.

Murry I. Rozansky

Thanks for the harbor freight tip. I am going over there today
to get some polishing pads.

-------------------------------------------------------------------

I think Polyethelene  would be too stiff for retrofit through small
holes.

If there are 2 ribs in your tank it could be done by cutting two 6 by 12 holes oval holes with three custom made bladders. The edge of the holes are near the ribs so connections can be made to the next bladder. I suspect it does not take long to make a custom bladder.

My 182 has a dozen access holes in the bottom skin :)

Sandy, Contact your local EAA chapter for help building the new wings.
All EAA people can learn from your experience.

Also get a bore scope and take a look inside. The harbor freight unit is marginal but home depot now sells them. I suspect it is better.

Paul Lamar