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.