Aviation fuel and the 70/30 mantra

Over the past few years, a debate has raged over the best way to reduce our dependence on avgas in North America, one of the last places on the planet where leaded fuels remain in use. There are two “camps” of thought.

The first one, consisting of the leaders of most aviation alphabet groups (with the notable exception of LAMA), contends that the best solution is to find a one-size-fits all, drop-in replacement for leaded avgas. Despite over two decades of searching for an alternative, this group doesn’t appear to be close to finding an affordable solution, but they have attended countless meetings, generated numerous reports and performed a variety of taxpayer-funded studies on the subject.

The second camp, made up mostly of recreational pilots and the managers of the airports they use, favor multiple options including avgas (or its eventual replacement), mogas, and Jet-A. Despite lack of support from the aviation alphabets and avgas suppliers, this second group is making slow, but significant progress towards broader availability of mogas, as this map of airports selling mogas from my co-author Dean Billing shows.

Given the success of the grassroots mogas movement compared to the failure of the well-funded avgas replacement folks, one has to wonder why the latter has not joined the former. Part of the answer, I think, is related to the so-called 70/30 myth of who uses which fuel.

It goes something like this: “While 70% of piston aircraft might be able to use mogas, the remaining 30% burn most of the avgas.” The AOPA repeats this mantra in this Regulatory Brief, but as in all such cases we’re aware of, provides no factual evidence of what appears to be little more than anecdotal evidence.

By comparison, your bloggers decided it was time to find some hard numbers, and this past summer commissioned a study of the FAA aircraft registry, which found that more than 80% of all piston-engine aircraft were capable of operating on mogas.

We still await a comparable, repeatable study from the avgas replacement camp proving their claims. Instead, some of the defenders of the 70/30 myth now refer to a 80/20 ratio; we suspect that if our study would have shown that 99% of all piston aircraft could operate on mogas, there would be those who would claim that the remaining 1% consume 99% of all the avgas!

In his January 2013 monthly editorial, High-Performance Composites Editor-in-Chief Jeff Sloan touches on a similar myth voiced for years by potential users of carbon fiber in the auto industry: “If only carbon fiber were $5/lb.”, then it would be a serious replacement for traditional materials like steel and aluminum, he explains. No one knows who started the myth and whether it is based on hard numbers, but it continues to be repeated as, Sloan contends, an argument for many in the industry to do nothing. “$5/lb has become a mantra mostly by virtue of repetition — and a sort of straw man for some automotive engineers and executives, who, deep down, don’t want to switch to carbon fiber and use the $5/lb threshold as a way to keep the composites industry at bay.” Sound familiar?

Sloan goes on to state that while the real cost for carbon fiber has not dropped, many related factors have, especially the mold cycle time, which for some processes is now down to 60 seconds.

The same can be said for aviation — while many continue to chant the 70/30 mantra, the aircraft industry, dealing with the reality of declining avgas supplies worldwide, has reacted. The fastest growing segment of aviation is Light Sport, aircraft whose engines are designed to operate best on mogas. Virtually all new piston engines are being designed to operate on mogas, including the new AF (Alternative Fuel) series from Lycoming and Continental.

Owners of large-displacement piston engine aircraft have been making the move to light turbine aircraft for years, prompting even small rural airports to add Jet-A tanks in addition to avgas and mogas. Jet-A burning diesels are real contenders these days for high-end pistons, as recent news from Diamond and Cessna shows and Flying magazine described this past summer. Electric-powered aircraft are no longer a novelty, with designs such as Randall Fishmann’s Electraflyer ULS now available for purchase.

Just as the $5/lb mantra among automakers blinds them to progress made in composite fabrication methods, so too does the 70/30 mogas/avgas mantra blind many in our community to the changes occurring in our powerplants that are enabling to us fly efficiently on a variety of fuels, including avgas, Jet-A, mogas and electrons. More choices are always better, especially when free markets — not committees and bureaucrats — determine what is best in each case.

Related posts:

  1. Predictions: Aviation fuel in 2013
  2. New fuel won’t be a drop-in replacement
  3. U.S. Investors Buy 200 Of New Brazil GA Design
  4. Virgin To Develop Fuel From Industrial Waste
  5. House Rejects EU Aviation Tax
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