Get the Lead Out

That was the name of the first session I attended at the Florida Airports Council 2016 Specialty Conference. As you can probably guess the session covered the ins and outs of an unleaded AvGas replacement…


The legacy fleet (composed of aircraft like this Boeing Stearman) present one of the larger challenges for the unleaded AvGas replacement efforts.

Following the General Aviation Committee meeting during the morning I used the lunch break of the conference to visit the World Golf Hall of Fame on the grounds at the Renaissance World Golf Village. A fan of golf since I was very young and a deeply average player of the game myself, I was excited by the opportunity to beat Jack Nicklaus at the Masters…


Quite the round at the Masters!

The “coolest” part of the World Golf Hall of Fame had an aviation component… It wasn’t the model airplane in Phil Mickleson’s locker either, instead the replica modified Wilson 6-iron that Alan Shepard used to hit golf ball son the surface of the Moon during his visit their as the Commander of Apollo 14. Many folks don’t know that Shepard and his crew were originally slated to be the crew of Apollo 13, but due to an illness that crew was pushed back to the 14th Apollo mission and Jim Lovell and his crew were moved up to the ill-fated, “successful failure” mission, Apollo 13.


A replica of Alan Shepard’s modified 6-iron, used on the MOON! (Totally out of this world!)

Back to getting the lead out… The presentation was very insightful from Shell Aviation. The first thing I learned during the presentation was the Jimmy Doolittle was the first Aviation Manager for Shell Aviation, the present manager for Aviation products, Dr. Tim Shea was one of the presenters about the AvGas replacement efforts in progress at Shell.

The FAA began the process of searching for an aviation fuel replacement for the still-leaded 100LL AvGas in 2010. At that point during the first phase of the search, 10 fuel companies responded. That number has been narrowed to two organizations, including Shell Aviation, that have made it on to Phase 2 of the program.

You might be thinking, plenty of aircraft fly on MoGas, non-ethanol, car fuel, so what’s the big deal? Well, that STC is for some types of aircraft, not the entire general aviation fleet. This fleet-wide replacement represents a much larger proposition for the FAA.

The new “drop-in” AvGas replacements must meet both ATSM and FAA standards meaning the fuel is safe to be sold, meeting specs and that it is able to successfully power aircraft and sustain operation across the legacy fleet of general aviation aircraft.

Presently, the lead in AvGas provides a boost of octane from roughly 91 to 100, when the lead is added into the fuel. This drop in octane in addition to the changes which come about as alternatives are added to the fuel mixture to bring the octane rating back up (to 100) account for the large R&D effort presently underway by Shell.

During the Q&A portion of the presentation I inquired about the scope of the flight testing. Reflecting on my time as an active flight instructor, I flew a large number of aircraft, with a variety of modifications since their original manufacture design. Thinking about how the placement of the carburetor on the engine can make an aircraft more or less susceptible to carburetor icing propelled me to wonder about the difference in composition being tested in so many atmospheric and aircraft/power plant/airframe/fuel system combinations…

The response from Dr. Shea was very insightful, one of the biggest obstacles to the “drop in” replacement efforts is the legacy fleet. There are so many aircraft variations, a variety of manufacturers that no longer exist, etc… The FAA having the ability to assure owners/operators of all of these aircraft that the new fuel will not present a safety issue for them is one of the major obstacles.

Ultimately, the replacement fuel must meet all of the specifications for aviation fuel (D910), then in theory it should work, right? What could go wrong… Many folks might take that approach, but I would be a bit more cautious. As I used to tell my students, you can’t just pull over on the top of a cloud if you have a problem up there!

Dr. Shea did explain that presently the FAA is testing the replacement fuels from Shell and Swift in a fleet of 12 different airframes with 20 or so power plant variations. The goal is to have each of those combination map a segment of the fleet or aircraft. At the same time, manufacturers such as Textron and Piper are able to test the replacement fuels in their present production models.

Another wrinkle to this is the comingling of fuel types – AvGas with either of the replacements, the replacements together, all three, etc… These are all part of the AvGas replacement conundrum.

From the sounds of the presentation, we are getting a lot closer to a “drop in” replacement, but work still remains. Keep your ears open and someday soon you just might see a new type of fuel truck at your airport! For us airport operators the next challenge is how the replacement will work. Will 100LL and the replacement need to be carried for a period? Will a new fuel tank be required? How does the changeover process work? Many questions exist, but the answers will come in time.

A few weeks after the FAC conference, I attended the Sport Aviation Showcase in DeLand, FL and spoke with a representative of Swift Fuels. Swift gave a much different view point on the topic, explaining that they presently have (available at multiple locations, including DeLand) an unleaded AvGas with a 94 octane rating. As of NOW, this fuel is available for use in most existing general aviation aircraft which simply spec AvGas. An example of an aircraft that cannot utilize this fuel is the Cessna 172S (and R model as well). The Pilot’s Operating Handbook (POH) specifies 100 or 100LL for the fuel, the 94-rated fuel doesn’t meet that requirement.

The Swift representative seemed less interested in the standpoint of the testing, reverting back to the point that the 100LL replacement fuel will meet all of the specifications for AvGas… Take that for what it is worth, we’ll have to see the results of the FAA trial. What remains to be seen is how comingling of fuel types during the transition and after the change over…

-Fly Safe, @MTElia1B9


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