AOPA Pilot Magazine - June 2022 - 86

RUDDER & WRENCH
necessary infrastructure and distribution
channels to support widespread usage of
these fuels. "
The blending and distribution infrastructure
will be similar to today's for
leaded avgas. If there are new points of
supply, adjustments will have to be made-
but that's standard practice for the energy
industry. The petroleum industry has
smoothly managed the shutdown of more
than 800 refineries over the past 45 years in
the United States alone (leaving some 130
in operation), and gasoline has continued to
be relatively economically available.
* " Continue to Evaluate and
Authorize Safe Unleaded Fuels: The
FAA will address fleet-wide authorization
of unleaded aviation fuels of different
octane levels. The Piston Aviation Fuels
Initiative will continue to evaluate, test,
and qualify high-octane aviation unleaded
fuels with the objective to ultimately transition
the fleet to unleaded aviation fuel. "
It's a little concerning that the FAA
is interested in fuels of different octane
levels, because the rest of the industry is
not focused there at all-avgas is already
a very small production product. Splitting
up that volume among different products
is uneconomical.
Through PAFI, the FAA's Technical
Center in Atlantic City, New Jersey, will
continue to work with the FAA-chosen
PAFI participants to qualify their fuels.
Swift Fuels and GAMI will continue their
own efforts to obtain supplemental type
certificates (STCs) for their fuels, with the
support of industry participants. Of course,
to the extent that the engine and airframe
manufacturers continue to revise their
approvals for fuels as Lycoming, Cessna,
and Continental have already done, STCs
may not ultimately be required for every
aircraft using these fuels. Either the PAFI
or STC process could lead to approval for
the entire general aviation piston fleet,
with varying degrees of paperwork for the
aircraft owner.
* " Establish Any Necessary
Policies: The EPA is evaluating whether
emissions from piston-engine aircraft
operating with leaded fuel contribute
to air pollution that endangers public
health. The EPA plans to issue a proposal
for public review and comment in 2022
86
AOPA PILOT / June 2022
and take final action in 2023, which can
lead to EPA regulation of lead emissions
from piston-engine aircraft. The FAA will
subsequently publish regulations that certify
piston engine modifications and new
piston engines that do not require leaded
aviation fuel, and regulate fuel components
for aviation fuels. "
That description doesn't quite capture
the core issue: The FAA acknowledges
that it's not quite certain just yet how
the PAFI fuels will be approved by the
administration. That obviously has to be
worked out, but the more recent indications
from FAA headquarters make the
PAFI approval look a lot like implementing
an STC approval. Note also that no one
seems to be seeking FAA help certifying
engine modifications for UL100, certifying
new engines for UL100, or regulating
fuel components. The existing process
and fleet are just fine for this transition.
But the FAA does need to figure out how
to approve the PAFI fuels, and share that
with GA aircraft owners. Even better, the
FAA has been asked to make an online,
expedited process available for filing the
necessary Form 337s and STCs to expedite
the transition. For example, did you
land at an airport with only unleaded
avgas, but you don't have the STC yet? Go
online via FBO computer or your smartphone,
and both acquire the STCs and file
them with Oklahoma City. The FAA Office
of Innovation says that's a great idea-but
the devil is in the implementation details.
Develop unleaded fuel
To understand the 100 unleaded avgas
challenge, you need to understand a little
bit about avgas formulation (put on the
lab coats). Generally, avgas has four components:
aviation alkylate for octane and
energy, light ends for vapor pressure to
assist winter starting, aromatics for octane,
and an octane booster to get the octane to
the 100 specification. For leaded avgas, that
booster is lead. For the unleaded avgas candidates,
the proposed solutions vary.
The solutions proposed by the five
contenders for a new formulation affect
the makeup of all but the light ends part
of this formula: substitution of novel aromatics
and octane boosters compared to
the components we've been using for the
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AOPA Pilot Magazine - June 2022

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