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.