Unleaded Fuels Part 3

Avgas by Any Other Name is...Avgas

  • Industry Insights
  • Michael J. Kraft, Senior Vice President and General Manager Lycoming Engines

Lycoming tests every engine that rolls off our assembly line. We take them into one of our test cells, attach a propeller and appropriate sensors, and then operate them through a range of tests. These tests can last from an hour up to four hours. We also use our test cells to evaluate components and new products. Every year we do this for about 3000-4000 engines. Lycoming purchases and consumes a lot of avgas.

So Lycoming has something in common with every owner and operator out there. We all experience pain at the pump. The price of fuel is going up for everyone, regardless of your mode of transportation. According to AirNav.com, the average price of 100LL between May 19 and July 13, 2011, was $5.79 (U.S.) per gallon in the United States, a 128 percent increase over the 2001 price of approximately $2.54 per gallon. In 2011 automotive "pump gas" is currently averaging $3.64 per gallon in the United States, a 254 percent increase over the 2001 low average of $1.04 per gallon. But wait, those "pump gas" prices are not at the aviation FBO. According to AirNav.com, the average price for "mogas" at U.S. FBOs currently stands at $4.44 per gallon, a whopping 327 percent higher than the 2001 automotive "pump gas" price.

Admittedly, these are averages and not representative of prices everywhere. Leave it to economists to figure out the comparison of 2001 U.S. dollars to 2011 U.S. Dollars, but the point is still valid. Fuel prices rose dramatically in the last decade and have made General Aviation more expensive. Coupled with the desire to move piston aviation to unleaded fuel and avgas distribution availability outside the Americas and Europe, the cost issue has created significant pressure to find ways to tap into the economies of scale that come from using higher volume lower-cost fuels like "pump gas."

Lycoming's automotive gasoline approval, however, did not allow "pump gas." We simply can't approve "pump gas" for our existing products if the first objective is airworthiness. What we did approve is a fuel from the "pump gas" production sources that is controlled well enough to provide predictable behavior on the engine - "mogas." Airframers would need to do the same. Lycoming believes companies advocating the distribution and use of automotive gasoline in aircraft ought to consider these same controls. Airworthiness by Design.

The Lycoming "mogas" is an option for the fleet that could use low octane fuel. It might be less expensive than 100LL - but we all know that retail price and production costs are two different things. We also know that the expenses for the "free" services provided by our FBOs need to be covered somehow, and that somehow is in the cash they generate from fuel sales. In the end the Lycoming "mogas" is a low grade aviation Page 2 of 2 fuel from automotive blend stocks. The same angle was previously attempted more than a decade ago with the ASTM 82UL avgas effort. You might have noticed that no FBO offers 82UL. That's an indicator that even when presented with an option, demand has not been sufficient to support a two-grade aviation gasoline fuel system.

Environmental challenges, price pressures and availability are all considerations for every owner and operator. It's the reason why Lycoming approved "mogas", but it's not "pump gas." It's an unleaded option that could be considered for aviation, but we fear the applicability is too low to be a universal solution and you will pay a premium over "pump gas." In our plant, we evaluate our performance as a business using five metrics. Four of those metrics are ranked and in order they are Safety, Quality, Delivery and Cost. The fifth is Leadership and Teamwork. Safety comes first and Cost comes fourth in the ranked items. We applied that same philosophy to our "mogas" approval where we designated the specification of "pump gas" such that we arrived at Lycoming's "mogas." THAT is how we achieve Airworthiness by Design, rather than by luck. We did it and did not publicize it because our fifth metric, Leadership and Teamwork, demands that we consider all the angles, and we did not conclude that industry and owners would be best served by a distractive argument on "mogas" - because in the end it's a low grade aviation gasoline with what we feel is limited broad application.

Concluding and as stated in our previous articles, Lycoming's goal as an engine manufacturer is to provide as much fuels flexibility for our customers as possible without compromising airworthiness. A "mogas" option could be possible for the existing fleet. In the end, if we all agree that Airworthiness by Design is the primary objective, "pump gas" cannot be an option for the existing fleet of aircraft.

The ongoing dialog that we are engaged in now regarding the distribution and use of unleaded automotive fuels in piston powered aviation needs to be solidly based upon the Airworthiness by Design consideration. It is an equally applicable argument in the use of jet fuels in Diesel or Otto cycle piston engines. You'll find the same consideration at the core of the FAA's Unleaded Avgas Transition ARC charter. Airworthiness by Design and the overall considerations outlined in this series are why Lycoming continues to believe that piston general aviation is best served in total by pursuing an unleaded aviation specification fuel to replace 100LL.

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Related Publications

Service Instruction No. 1070

Lycoming has resources on aircraft fuel. Read the related publications so you can make the right choice for your Lycoming engine.