Hi Mike,
In terms of practicality and safety, our low compression Continentals
(Ercoupes, not the later Forneys, etc. with 90 hp) were perfectly
content with 73 octane fuel. 87 Octane is overkill. 90 octane is
overkill. Not sure why 91 Octane was chosen for the STC testing, but
suspect some sort of compromise (one size fits all) between what was
available at the pumps nationwide at the time and the engine
compression ratio requirements of the more numerous light aircraft in
the general aviation fleet needed.
I believe experience has shown over the years since the demise of 80/87
aviation fuel that substituting 100LL has more expensive side effects
in terms of valve sticking from excessive lead buildup (over four times
the lead content of 80/87) requiring more consistent and aggressive
leaning in operation on the part of operators pursuing the benefit of
full "TBO" hours between overhauls. I'm sure there have been
unnecessary deaths caused by related engine failures and/or forced
landings that would have been properly attributed to 100LL use in
engines never designed for it.
Had the FAA been as interested in phasing in and regulating "aviation"
Mogas to replace of 80/87, FBOs would never have had to evaluate
whether or not to offer it...but only the markup. The separate tanks
and dispensing pumps were in place.
But, as usual, our government was and remains more interested in the
on-paper "legality" of fuel, parts, installations, etc. in order to
avoid any possible responsibility for any and all problems, known or
unknown, than in accepting their legitimate mandate to promote aviation
by keeping costs as low as genuine safety concerns allow. When the
EPA, et al, began mandating alcohol in auto fuel, the FAA could have
acted proactively to fund a study to determine how many and which
refineries would accept "designated provider" status to continue to
offer "aviation" Mogas (without alcohol or other adverse-effect
emission reducing additives. Why am I not surprised that the FAA
conspicuously ignored the situation?
Had they done so, more lead would have been removed from the
environment, both earlier and long term, with reduced burning of 100LL.
This would have pleased the EPA, who might have come "on board" if
someone (anyone) else did the necessary slogging. But the foresight
and leadership necessary happen to be the very attributes any
bureaucratic culture actively and instinctively discourages.
The driving forces of reducing lead emissions, raising octane of
unleaded fuel, maintaining btuh content per pound of fuel, substituting
"renewable" fuels, in whole or in part, for fossil fuels, and helping
the "bottom line" of American farmers are frequently in conflict. The
"best" solution to such a process depends on "who's ox is being gored"
and how many votes are associated. The result is certainly never going
to result in one fuel that will efficiently meet the needs of the
existing general aviation fleet because no one in government had been
given that responsibility or a budget with which to accomplish same.
Marathon's fuel is probably 90 Octane for the very reason that they
don't want the hassle of dealing with the FAA on behalf of aircraft
owners wanting to use it...a pittance of any volume they produce and
distribute. If your local FBO buys the Marathon fuel, he would have to
add a bit of 100LL to bring the octane up to STC specification; and
your guess is as good as mine as to how he would blend the two and how
uniform throughout a given tank full such a blend would be. I see no
reason individual pilots couldn't pour a gallon of 100LL in each dry
wing tank and finish filling with Marathon's boat fuel to meet STC
requirements.
As to the danger of bringing fuel to the airport and filling your own
plane...consider these facts. During WWII, aircraft operating in
remote locations were frequently fueled by human beings from the five
and fifty gallon metal containers in which the fuel was transported
from the states. I don't remember reading stories about huge
casualties being associated with this practice, probably because there
were likely very stringent and well supervised regulations that made
the process a safe one. If people will stick to appropriate
procedures, such as NOT using plastic containers, not fueling cans in
vehicles (on the ground only), and buy and faithfully use appropriate
clip-on grounding wires there is no inherent reason an intelligent
person should be subject to undue risk in fueling their aircraft any
more than in fueling their mower, weed eater, or any other gasoline
powered equipment.
Of course FBOs who seek to hold aircraft owners using a given airport
hostage for maintenance or fuel by legal means rather than good service
and "common cause" in keeping the airport open, municipalities who get
a percentage of fuel the FBO sells, or the insurors of either who wish
to minimize risk for premium paid will always look to the occasional
idiot that manages to flambe themselves, their car, their plane, etc.
because they are too ignorant of proper procedure or too lazy to follow
it and the inevitable heirs (same gene pool) who would, with their
attorneys, flock like the buzzards they are to each scene of such
carnage.
So long as everyone genuinely wants something for nothing, there can be
no answer. Never forget that no government would approve the use of
gasoline as a fuel if the idea were new today. Transporting it through
cities would be unacceptable in terms of risk, as would be dispensing
it or even having passengers ride around in such close proximity to
such hazard. Good thing the idea was so firmly entrenched by our
forefathers long before unelected and unaccountable bureaucrats assumed
omnipotent powers and periodically rewrite their own job descriptions.
(off soap box)
WRB
--
On Jan 31, 2010, at 14:48, Mike Powell wrote:
I just purchased a Mo gas STC from the EAA because Marathon Oil has
come out with a 90 octane fuel that is being sold at Kwik Trip and
Caseys stations here in WI. Kwik trip labels their pump as
recreational fuel. Not real handy to carry 5 gallons to the airport -
still it's a $1 a gallon. Our local FBO has agreed to sell Mogas this
summer. It may do a lot to get people flying. The STC cost is $1.50
per HP.
"Marathon Oil Company is marketing a 90 octane unleaded non-ethanol
gasoline as a recreational fuel for boats. This fuel is perfectly
suited for use with 87 octane auto fuel STC's. In some locations it is
one octane point higher, 91 octane. 91 octane is suitable for use with
all auto fuel STC's. "
Mike
Do not be mislead by popular opinion.
