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Al,
When I
built my cozy, the EZ-poxy was also recommended for the strakes. Since I
used MGS to build the entire plane, I really didn't want to use the EZ-poxy to
build the strakes. For one, it would have different curing tendencies, and
secondly the specifications of the MGS indicated that strength wise it was a
much better epoxy.
After
some research, which also included using products already tested by others
before me, I elected to coat my fuel tanks with a product made by Jeffco.
Specially, Jeffco SPF9700-FCR. I built the strakes using MGS, and then
coated the interior with the Jeffco epoxy.
I'm
not sure how difficult it would be to coat the tanks with it now, but it is
impervious to most fuels, and their various additives. I've had fuel in my
tanks for almost 3 years now. Various different gas stations, and no
problems at all with the tanks.
I
don't know how hard it would be to coat your tanks now, but it most likely would
solve your problem. You just paint the stuff on after mixing it up.
It's pretty thick, and tends to stick pretty well to vertical surfaces. As
I recall, I gave mine 2 or 3 coatings. I had zero leaks when I pressure
tested the tanks.
Steve
Brooks
Cozy
MKIV N75CZ
Turbo
Rotary
Not sure where to go with this
because there are only a few here with epoxy fuel tanks, and on the Velocity
list very few interested in the use of mogas. I’m suspecting fuel
compatibility isses.
I first put fuel in the tanks
nearly 2 years ago and used Chevron regular. Everything was fine. When I
moved the plane to the airport 3 months ago (tanks empty) I filled with
Exxon-Mobile. Four troubling things have come up in the past few weeks.
- I have Vance Atkinson site
gauge that has a white plastic back plate for easier reading of the fuel
level. The small hole through the backing has been swelling shut so the
sight gauge no longer works. I contacted Vance who said that there are
hundreds of these gauges in EZs using mogas without problems, but he has had
3 incidents like mine in the last three months.
- A couple of weeks ago there
was suddenly a pinhole leak in one of the gear well enclosures. These
enclosures are part of the fuel tank wall, and are parts that come with the
Velocity kit. These are also made and coated with
EZ-poxy.
- Looking in through the filler
cap I see reddish-purple splotches and streaks on those gear leg
enclosures. Poking and scratching with some safety wire on a stick
does not indicate any softness of the surface.
- Yesterday, under the leading
edges of one of the strakes, I noted an area with some slight surface
irregularity. Pushing on it suggests some sponginess. This is ½”
foam core material, and indicates the possibility of a pinhole leak in the
inner skin, and fuel softening the PVC foam. PVC foam is supposed to
be unaffected by fuel.
My tanks (strakes) were made and
coated with EZ-poxy back in 1998. At the time I polled EZ flyers about
there experience, and talked to reps of various epoxy manufacturers about auto
fuel compatibility. All the evidence said go with the
EZ-poxy.
Any others with composite tanks
having any trouble? Anybody using Exxon-mobile fuel? Know of any
new additives that are an issue?
I’m thinking I should drain this
fuel ASAP, but then what? Other brand? That expensive Avgas?
Regardless I may be faced with cutting open a strake at some point, but right
now we are trying to get first flight done this coming
weekend.
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