Re: Fuel Tanks

Darrell Daniels <log@...>

Thanks Bob,
The leak test is what I was thinking I needed to do. What got me started on this again was I asked why I could not run auto fuel in a VW engine and one of the answers was that someone heard that auto fuel would penetrate the epoxy. I am actual glad for this as I have learned a lot from this thread . My thanks Darrell Daniels Tri Q rebuild

----- Original Message -----
From: "Bob Farnam" <bfarnam@...>
To: <Q-LIST@...>
Sent: Wednesday, September 13, 2006 11:33 AM
Subject: RE: [Q-LIST] Fuel Tanks

If nothing extra was done by the original builder, there is some chance that
it will leak. If you can't find out what was done during construction, then
I guess my next step would be to do a long term leakdown test. This can be
done by sealing up all of the openings except the supply line to the pump.
Then put an inflated balloon on the supply line and let it sit for 24 hours
to see if any volume is lost. Check all the seal points with soapy water. If
it is tight, go fly. If not, cut some holes and at least paint on more epoxy
inside. Unfortunately, the internal baffles mean that you will have to cut
holes into each section between the baffles. Hope that it passes the
leakdown test. Understand that a tiny amount of leakage into the fuse foam
won't hurt the foam, which is fuelproof. Only the Styrafoam in the wings is
at risk of dissolving. I recommend against any sealant except epoxy. I have
heard (but don't know firsthand) that some of the elastomer sealants are
attacked by auto fuel. Others on this list may know about that.
Incidentally, EZ-Poxy is supposed to be the modern equivalent of
Safe-T-Poxy. My 7.5 gallon aux. tank is made of EZ-Poxy and is fine after
about 7 years.

Good luck!

Bob F.
-----Original Message-----
From: Q-LIST@... [mailto:Q-LIST@...]On Behalf Of
Darrell Daniels
Sent: Wednesday, September 13, 2006 6:00 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Fuel Tanks

I did not build my airplane so what would be your recommendation Would you
just put the auto fuel in and fly or cut some holes in the top of the tank
and seal it with something. Thanks Darrell
----- Original Message -----
From: <bfarnam@...>
To: <Q-LIST@...>
Sent: Wednesday, September 13, 2006 1:16 AM
Subject: Re: [Q-LIST] Fuel Tanks

> Here's one more data point for you Darrell. My Q200 has been flying for
> more than 8 years using auto gas when I am at home and 100LL away on a
> trip. My tanks are made of Safe-T-Poxy. I have also had a sample of the
> tank material soaking in auto gas with MTBE for about 7 years. There is
> sign of softening or other problem. The main source of leakage that I
> seen is into the fuselage layup which typically had a lot of pinholes.
> Those can be sealed several ways during construction. Either sand and
> recoat with a fairly heavy layer of epoxy, or some have added another
> layer of glass. Mine is sealed with just an extra coating of epoxy.
> properly, the epoxy tanks won't leak.
> Bob F.
> N200QK
> ----- Original Message ----
> From: Darrell Daniels <log@...>
> To: Q-LIST@...
> Sent: Tuesday, September 12, 2006 8:19:03 PM
> Subject: [Q-LIST] Fuel Tanks
> I have been searching the archives as I am still not satisfied with the
> idea
> that fuel can leak through you tank and into the foam of you airplane .
> also wan to burn auto fuel . After all of my reading it seems the only
> people who have actually done anything is using a slosh coating which
> not
> really practical it a Q but it seems to be the only option is you want
> burn car gas or rid of the possible fuel leak.
> The one exception is in the Archive Sam in one entry said something
> about using a fuel resistant epoxy but you could not get to all of the
> places to sand to easily recoat the entire inside of the tank. Any
> ideas or am I making much to do for nothing Darrell Daniels Tri Q
> Quickie Builders Association WEB site
> Yahoo! Groups Links

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