On Jan. 19 your bloggers posted a rebuttal to an article in EAA’s Sport Aviation titled “Avfuel Takes on Fuel Challenges” by J. Mac McClellan that deals with the never-ending saga of a replacement for leaded avgas. We did our best to correct the fallacies in the article. Judging from the numerous positive comments we received, most of you agree with the facts that we presented.
In the immortal words of then-candidate Ronald Reagan during the 1980 debate with president Carter, “There you go again.” Incredibly, the February issue of Sport Aviation included a new article (“Fueling the Future of GA” on page 10) that contained even more misleading statements on aviation fuel that demand correction.
First, the author appears to have misunderstood the goal of Airworthy Autogas. This new company is not focused on the fuel that was tested and approved via EAA’s autogas STCs, but rather the automotive fuel that Lycoming specifies in Table 2 of its Service Instructions 1070S. Lycoming calls for an AKI of 93 and a vapor pressure (RVP) of no more than 9.0. (None of the EAA’s auto fuel STCs require an RVP as low as 9.0 and they do not call for more than 87 AKI .) Note too that the 1070S document makes no mention of an aviation-specific fuel in Table 2, since automotive fuel worldwide must already meet ASTM D-4814 or EN 228:2008(E).
Petersen Aviation continued testing on higher compression engines that may operate on 91AKI autogas and has numerous STCs to show for it, including those for the Beech Baron and Cessna 210. This is significant because it proves that auto fuel need not only be used in the realm of J-3s and Cessna 150s, but could also be used in larger, modern high-powered airplanes.
Second, the article suggests that auto fuel has changed greatly over the past 30 years, “and sometimes not for the better.”
Not for the better insofar as ethanol is concerned, indeed that is true.
Fortunately there are simple tests that anyone can perform to determine the presence of ethanol, so the chance of its use by mistake is miniscule.
Furthermore, airports that sell auto fuel do not purchase it from local gas stations, but from terminals before ethanol is added. Still, those who self-fuel have more than 7,700 gas stations to choose from where ethanol-free (E0) is sold, which can be easily found at Pure-Gas.org. (I have its free app on my iPad to help me find E0 for my cars, the fuel I prefer).
The prevalence of ethanol in gasoline is the only downside (significant though it may be) to making use of an auto fuel STC — but remember that airports do not buy their fuel at a gas station. Aside from the ethanol, auto fuel is cleaner than it ever was and has a lower vapor pressure than it ever did. Indeed this makes it more like aviation fuel than ever. So to imply that today’s auto fuel is somehow out of spec or unusable is a complete falsehood.
We welcome Lycoming’s work toward its 93AKI auto fuel because it vindicates the basic chemistry of the fuel. Lycoming would not be approving auto fuel if there were issues with it. Nor would Continental, Rotax, ULPower, Jabiru, D-Motor, AeroVee, Viking and nearly every other aviation piston-engine manufacturer that now type certificates their engines for auto fuel.
Finally, in the fourth paragraph of the article the statement is made that an unleaded replacement for 100LL must be producible in large quantities, distributed throughout the nation with a whole new infrastructure, and should be economical enough not to deter flying. There is only one fuel that meets those requirements today and that is likely to continue to do so in the years to come, and that is 91AKI automotive gasoline, supplied today to more than 100,000 gas stations in the US through a vast network of highly-competitive, independent fuel distributors.
The argument that FBOs cannot afford an additional fuel tank for mogas is a red herring too — modest self-service fuel systems cost less than $40,000 and pay for themselves in a few years. Small airports across the country are adding self-service Jet-A fuel systems, not because turbine aircraft are based there, but speculating that they might be one day if the fuel existed. Why not do the same for mogas and get people flying again who can not afford $8 avgas? Many small airports these days manage to find the funding for palatial terminals with rarely-used meeting rooms comparable to Wall Street board rooms — funding is clearly there for those who seek it.
Lastly, the EAA article repeats the “70/30 mantra”, claiming that a small number (less that 20%) of aircraft that need 100LL consume most of the fuel sold. Fact is, over 80% of all piston-engine aircraft today can operate safely and legally on mogas, as shown in our study from 2012.
In Europe, where poor weather restricts GA flying for half of the year, mogas is widely available at airports and has been reported as constituting over 50% of all fuel sold for piston aircraft. Why is it impossible to do the same in the U.S. with its larger pilot community?
And what about those high-performance, 100LL-burning aircraft? Using the same water/methanol injection system that has been approved by the FAA and in use since 1989 on 210s and Barons (INPULSE), the remaining 20% of our GA fleet could be converted to 91AKI auto gas if only the alphabets would get on board. This is not likely though since the people involved with the selection process have all voiced their support for a 100 octane solution only and refuse to consider anything else. This is unfortunate given that we’ve had the solution right in front of us for over 30 years.
Whatever fuel prevails through the selection process set up by the FAA, let’s hope it’s priced less than what we’re paying today for avgas. Too many people are dropping out because they cannot afford 100LL and now with ethanol prevalent, those who self-fuel have difficulty finding aviation-grade auto fuel at gas stations.
Insisting on 100 octane means the cost of production will be much higher than it would be for a 91 or 93AKI. If the new fuel cannot be made less expensive than today’s 100LL, then eventually only the very wealthy will be able to afford to fly.