Tom Parkes wrote:
The latest issue of Contact! magazine (issue 66) should be read by any
and all Lancair builders using automobile engines. John Harlow
describes two independent problems encountered in his Chevy 350-powered
Lancair ES, which was damaged during an emergency landing last year.
The emergency landing followed a bearing failure on his Northwest Aero
belt redrive, and was discussed on the ACRE newletter.
The other problem he experienced is an apparent incompatability
encountered between mogas containing ethanol and the Hysol adhesive used
by many Lancair builders to close out their wings (including me). Hysol
has been typically used due to its longer working time as opposed to the
Jeffco epoxy formula most Lancair builders have been previously using,
which would set up before wing closeout could be finished. (Jeffco has
recently developed a longer cure time version of its epoxy system, and
Lancair now recommends its use for this critical operation.)
John's Lancair ES developed persistent fuel tank leaks after about four
years of flying with automobile gasoline. He discovered that the Hysol
squeeze-out from the seam at the closeout interface was being weakened
and breaking loose. Samples were sent to Lancair and Hysol for
analysis. Hysol said that there must have been some alcohol in the
fuel. Indeed, Tucson mandates seasonal use of ethanol to reduce
automotive emissions.
So, where does this lead us? First, any Lancair builders who have not
closed out their wings should consider the new slower curing Jeffco
epoxy. For those of us who have already crossed this divide, great care
must be exercised to avoid any auto fuels containing any kind of alcohol
(usually ethanol). Test kits are available for this purpose.
100LL avgas apparently has no adverse effect on Hysol adhesive, as
attested by several hundred Lancair builders who have successfully used
Hysol for many years. But use of 100LL in auto engines apparently has
its own set of precautions--espcially for those of us using Mobil 1
oil--if we can generalize from Mobil's abortive venture into aviation
engines.
Any other experiences along this line? Anyone?
Tom Parkes
Lancair ES
Prescott, AZ
tparkes@earthlink.net
Aircraft should be designed with materials that are compatible with ethanol.
The constant problems that we in aviation have with water in fuel could be
solved by using ethanol in fuel. Unfortunately we remain stuck in a
technological backwater because of all of the paperwork and headaches
associated with doing anything new. Ethanol makes water soluble in the fuel
and eliminates a lot of the water/fuel/freezing problems. I have known of
Beech 18 pilots that actually put alcohol in the tanks to get the water out
because of the problems those aircraft have with condensation. Perhaps we
could use compatible epoxies or use fuel bladders in the tanks. Another nice
thing would be a sealed fuel system similar to an auto system that reduces
condensation in the first place. This could be accomplished using bladders
also. Anybody out there know of any other reasons pro/con regarding the use
of ethanol?
Monty
I recall that in that same article, Hysol suspected
that methanol had been present. There is a fairly
wide experience base with ethanol based fuels in
both metal and composite aircraft, that purports to
no problems. With certified aircraft the primary
problem has been with bladder materials, - Vance J
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