Mogas and the myth of liability

Recently a GAfuels reader sent us the following message: “Yesterday I had some work done by a Rotax maintenance facility near me. During our chat, we recounted his experience and training as an A&P, IA, pilot and FBO owner. With Rotax-powered aircraft of his own and a source of income for his business, I asked him why he didn’t sell mMogas. His answer was immediate and it was “liability.”

I asked him to explain further and he said that 100LL was a high quality product with multiple filtering and high quality control while mogas was anything but. He didn’t want the liability exposure from something happening to a fuel customer due to a fuel issue that could cause him liability exposure. I asked him about other FBOs that did sell mogas and he commented that their sensitivity for liability exposure must be a lot lower than his. I’m curious about your thoughts.”

This is one of the top 10 myths surrounding mogas. The cost for liability coverage for mogas is modest and offered by most major aviation insurance providers. But it is not free, which is what he is probably seeing, as it is often included in contracts for avgas and Jet-A. To find an insurance provider, we suggest he call his favorite aviation insurance company or any of the 120 or so airports offering mogas found on my co-blogger Dean Billing’s list and map.

One question to ask such skeptics is why they think that gasoline producers and convenience stores are less liable for hundreds of millions of vehicles compared to a relative handful of aircraft? Both fuels must meet well-defined ASTM standards, D-910 for avgas and D-4814 for gasoline.

While there may be some difference in filtering at refineries for different fuels, the filtering that matters most is just before the fuel enters the tank of an airplane, and this means the filters on the fuel system at the airport. As a representative of a major supplier of turnkey aviation fuel systems, U-Fuel, I can guarantee that there is no difference in filtering whether the fuel is mogas or avgas.  In fact, the Velcon filters we use on our systems (and most others you’ll find) are designed to prevent the tiniest solids and water from getting into an aircraft. They are probably better than what one would find at the corner gas station.

Again, there is no difference in filtering for aviation fuel systems that dispense mogas compared to avgas. This FBO owner is probably thinking of mogas purchased at a gas station, which can be a different ball game altogether.

We would always recommend airports obtain mogas from a fuel terminal, where you will receive a printed receipt guaranteeing what you’ve purchased, i.e., ethanol-free, ASTM D-4814 compliant and of the correct AKI rating as specified in an aircraft’s Type Certificate or mogas STC. Transport the fuel in a quality truck and store it in a quality tank at the airport and there is no more risk than with any other fuel. As long as the mogas contains no ethanol, its shelf-life, according to GA News blogger Ben Visser, is up to six months.

If one does buy mogas from a gas station, we follow Petersen Aviation’s recommendation: Buy only branded gasoline, the highest AKI they have (even if you can get by with lower), and always check for ethanol.

Traditionally some pilots pour their C-Station mogas through a chamois cloth when fueling their planes, as a poor-man’s filter. We’d recommend instead they work with the airport’s owners to install a permanent, aviation-grade mogas storage and dispensing system to maximize quality and minimize risks and costs.

Buying mogas from an airport also results in more sorely-needed aviation fuel tax revenue; buying at the gas station just earmarks your fuel tax for repairing roads and subsidizing public transit.

If you do self-fuel, remember to use good grounding practices every step of the way.

Lastly, the FBO owner’s concern that airports selling mogas are more risk-tolerant is not consistent with our experience. Nearly all public airports are owned by a city or county and they all have lawyers concerned about liability. Nevertheless, well over 100 airports across the United States sell mogas alongside avgas, even within states that are considered friendly to trial lawyers.

Todd Petersen of Petersen Aviation, who has more experience with this subject than most, commented on liability for mogas: “There is more liability in general with airplanes than with automobiles, but in all aspects — not only fuel.  However, I’ve never heard of an FBO being sued over the auto gas he was selling. Unless someone can show a lawsuit, then there is no actual increase in liability.”

If misfueling of aircraft is a concern, one ought to review the history of misfueling between avgas and Jet-A. While rare, it does happen, despite the best efforts of FBOs to label pumps and provide other means to prevent this.

Once again, this FBO manager demonstrates that ignorance is one of the primary reasons we do not have more mogas at airports. In his defense, avgas suppliers have very little knowledge of mogas, and our aviation alphabets have not done much to educate their members on the facts concerning mogas, the only generally-available, lower-cost, lead-free aviation fuel we have.


  1. Michael Gallagher says

    This past weekend I flew 7.5 hours all on one tank hitting multiple airports around the Chicago area that I hadn’t landed at previously. With a Rotax 912, I throttled back to enjoy the day low and slow. Turns out I burned about 3.25 GPH even with 11 landings at 11 different airports. I have 27.5 gallon tanks in my Rans S7S and could have completed the day at 110 mph instead of 100, but then my fuel burn goes up over 5 GPH. My fuel cost for the entire day was less than $100. Meanwhile on the east coast, a friend of mine got in his 4 seat piper with 3 seats empty and $166 for less than 3 hours worth of avgas. He may have gotten there a bit faster, but my wallet is still full.

  2. unclelar says

    What is the one thing that most all of us who fly for fun could benefit from the most and is actually doable? Reasonably priced and readily available mogas at our local airports. Never have understood why the alphabets haven’t been all over this.

    • Kent Misegades says

      We agree. Quite a few sport aviators have urged the alphabets to support ‘fuel choice’ instead of remaining fixated on one-and-only-one solution. Free markets are the best means to sort these things out, and not all airports will have the same mix of fuels. One major exception to this criticism is LAMA, the Light Aircraft Manufacturers Association, the nice folks led by Dan Johnson (GAN Blogger SPLOG) and focused on LSA. It is no wonder that the LSA sector is the only one growing significantly, and most of these factor-new aircraft are type certificated for mogas.

  3. John says

    So, what exactly does “proper grounding” mean in operational terms? Sure, attaching the grounding wire, standing on a metal ladder and maintaining contact between nozzle and inlet rim will do it. Standing on the ground bare foot wile pouring fuel into the wing might. How about all these fuel trucks with non-conductive (plastic) ladders? Or the guy or gal with a pickup load of plastic jugs? Fueling fires aren’t every day events, but they do happen. The “liability” thing goes beyond FBO fueling. Lots of comments posted online allude to the “proper” technique. What does “proper” technique mean?

    • Kent Misegades says

      John, I was referring to the importance to attach a grounding wire to the aircraft before any fueling. This should be attached to a rebar rod sunk deep into the ground, or the equivalent. Best is to store fuel only in metal fuel containers, which are hard to find. Make sure that static electricity has a path other than fuel vapor to escape. For instance, the fuel nozzle should be in contact with the fuel filler neck before any fuel is poured into the fuel tank. I know of three cases of fires caused by inadequate grounding; in one case, an A&P friend was horribly burned as a result.

    • Kent Misegades says

      Like most modern European aircraft engines, the Rotax is designed to operate best on 91+ AKI ethanol-free mogas. Anything else has negative consequences. Rotax does a good job of explaining this in their documentation. Note that in Austria, where the Rotax is designed and manufactured, Mogas is available at most airfields. Obviously they are designing their engines for the European market, so we need to work harder to get ‘their’ fuel onto our airports, eg mogas.

  4. Len says

    Kent, useful information as always. Here’s a new one for you: We got a new FBO owner at our place a couple years back. From day 1 he talked about offering mogas. Recently I asked him about it. He told me he had to shelve those plans because his contract with his Avgas/Jet-A supplier specifically forbade him from offering mogas as well. This FBO sells one of the top brands of Avgas purchased from one of the largest Avgas distributors in the eastern half of the country. I don’t doubt what he says, but it seems to me that sucha contract would run afoul of various laws and rules that attempt to guarantee fair competition. (Yes, our field is public and has received FAA grant money.) Any thoughts on this?

    • Kent Misegades says

      I doubt that such a contract would ever stand up in a court of law, as being terribly anti-competitive. That would be like a Cessna Pilot Center signing a contract that would forbid the airport to allow anything other than a Cessna to operate at the airport. I suggest you remind the airport commissioners that they must abide by FAA Order 5190.6B, chapter 8, which forbids exclusive fueling at publicly-supported airports.

      If you are referring to Shell Avgas from Eastern Aviation in New Bern, NC, I am not too surprised really. They know nothing about mogas. I wonder if they know that Shell stopped producing Avgas 21 years ago? They buy it from unbranded producers.

      • Edd Weninger says

        “If you are referring to Shell Avgas from Eastern Aviation in New Bern, NC, I am not too surprised really. They know nothing about mogas. I wonder if they know that Shell stopped producing Avgas 21 years ago? They buy it from unbranded producers.”

        A curious statement. A friend of mine owns an FBO at a small airport. He has a 100LL avgas contract with:

        Shell Oil Products Company US, DBA
        Shell Aviation and Eastern Aviation Fuels, Inc.
        Conway, AR

        As part of the contract, he is required to carry a small amount of Aviation Commercial General Liability Insurance. In turn, he is covered by $50,000,000 of liability insurance from Shell Oil US.

        So, I would think they would know about mogas and avgas. And the product is good enough to carry the Shell brand.

        His contract has no restrictions mentioning mogas, but he cannot see selling enough to be profitable.

        And, as I’ve mentioned before, you misread or misinterpret 5190.

        • Kent Misegades says

          Shell branded Avgas, from an unbranded manufacturer is of the same ASTM D-910 quality as other brands. I can not imagine that Shell would put its name on anything less. We know of a number of instances where these anti-competitive clauses in contracts have been contested and defeated. Competition is always better, not only for consumers but the sellers, too – a rising tide raises all ships. The lack of competition in fuels has the expected consequences – high margins, high prices, plummeting hours flown and massive losses of licensed pilots. Why an airport owner would permit this to happen, knowing that he’s shooting himself in the foot, defies explanation. There is no guarantee though that any product will make a profit, mogas, avgas or Jet-A. That is what free markets determine. Just as you will find little Jet-A on grass airfields popular with sport aviators, mogas will probably not succeed at an FBO catering to corporate aircraft. One thing is for certain – at airports where exclusive agreements are tolerated, no avgas is being sold to people who have stopped flying. Here in central NC, only one of ten light aircraft are flown regularly. The average number of hours my A&P son sees on aircraft coming in for annuals has dropped below 25. For some, the only hours flown are to and from the shop for an annual. That is the direct consequence of higher fuel prices that mogas can help to offset.

          • Edd Weninger says

            “Shell branded Avgas, from an unbranded manufacturer is of the same ASTM D-910 quality as other brands. I can not imagine that Shell would put its name on anything less.”

            Exactly my point. It seemed to me, in your first statement, you were suggesting Shell/Eastern bought unbranded product from back-alley refiners, and just slapped a Shell logo on it.

            I also question your premise that “competition is always better”. Yes it is better when there is enough market to sustain more than one supplier and/or more than one type of fuel.

            I operate from two major airports in SoCal which have multiple providers of avgas and jet-a. At both fields, the price of avgas is higher than the smaller fields around with only one provider. Why, lots of reasons we really can’t get into here, but they involve property values, lease costs, etc.

            I also frequent smaller airports in AZ which have only a single provider. Prices are less than SoCal for both avgas and jet-a. Without doing a thorough analysis, I think neither field could accommodate a second provider with both making a profit.

            GA, as we have known it, is going away. But, not because of the cost of fuel. Flying has always been expensive, and always will be. It is not affordable for the average person, and never has been.

            A buck less per gallon for planes that burn ~10 gph is not the salvation of GA.

  5. Dennis Reiley says

    This of course begs the question, “Why is mogas treated separately from avgas and Jet A?” A second question is why special grounding is needed when fueling. Special grounding is only needed if the person doing the fueling is on the aircraft and not standing on the ground. For cars and aircraft the human body standing on the ground is an excellent ground and has been safely done since the invention of the internal combustion engine. The only instances of fueling fires and explosions that I’ve ever heard of occurred when the fueler or a bystander did something stupid.

    • Joseph says

      Cars have a tighter fuel neck and most pumps have a vapor shield. There are many fires from people getting into their car while fueling and sliding on the seat generates static electricity and then they go to remove the nozzle and spark.

      Also the prop spinning in the air generates a fair amount of static that may not get dissipated in the time between pulling up shutting down and starting fueling.

      Grounding isn’t needed 99% of the time, but the outcome in the case of that 1% makes proper grounding time and money well spent. Usually the static is dissipated in some manner before its an issue. Same goes with working on electronics I’ve been doing it for years, self taught myself how to fix circuits when I was 12. I didn’t learn about grounding until college, but during that time I only fried one VCR with a static shock.

    • Kent Misegades says

      Mogas and Avgas are chemically and electrostatically nearly identical. Grounding is an issue when people pour fuel into aircraft without using a grounding wire. What makes this worse is the use of plastic fuel containers, which will quickly build up a static charge when pouring fuel, especially in dry conditions. Airport fuel systems use special hoses that contain grounding wires that provide a path for static electricity to travel from the filler neck, down the hose, and eventually into the grounding rod that is attached to the fuel system.

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