Recently we heard from an exasperated reader from a major general aviation airport in southeastern Texas. Like many of his fellow recreational pilots in the Lone Star state, he had asked his new airport manager for help getting mogas onto the airfield as a means to lower the cost of flying. He had even gone to the effort to find a surplus fuel tank and a supplier of aviation-grade mogas (ethanol-free, 91+ AKI). The response from the airport’s manager is sadly typical of the confusion that remains prevalent in aviation. I have paraphrased this below:
“He said that since the airport is a federally-funded, the Texas Department of Transportation won’t let them put in mogas because they lose their federal grant money. He also said that the planes that have the STC to run car gas are not allowed to run car gas since it’s not an FAA-approved fuel.”
Where does one start with this statement?
First, according to GAfuels co-author Dean Billing’s accurate list, there are at least six airports in the state of Texas offering mogas. Three of these are publicly-owned.
Second, the whole point to an FAA-approved mogas STC is to permit aircraft to operate on mogas. Some 60,000 such STCs have been issued by the EAA and Petersen Aviation since 1982. Nearly all new aircraft engines developed in the past few years may be operated on mogas according to the TCs and do not require an STC; the best such examples are the ubiquitous engines from Rotax and Jabiru on the latest generation of training and LSA aircraft.
Lastly — and this is an important point — the FAA does not approve any fuels; it only approves engine/airframe combinations to operate on fuels defined by organizations such as the ASTM. For instance, 100LL is defined by ASTM D-910 and mogas (gasoline) by ASTM D-4814. Mogas TCs and STCs have additional requirements regarding the AKI rating and the prohibition of ethanol.
During AirVenture 2011 I met by chance the new manager of general aviation for one of the nation’s largest avgas suppliers, coincidentally the same company that delivers avgas and Jet-A to the airport mentioned above. When I asked him why his company would not deliver the same premium, ethanol-free fuel that they supply to many gas stations, he looked confused and stated that the fuel for all piston aviation engines was required to contain lead. Over the following several weeks, I slowly educated him on the long, successful history of mogas as a legal, safe aviation fuel and the fact that the vast majority of the current piston-engined fleet can operate on it. In the end, he admitted his previous ignorance but used the typical excuse that his company’s lawyers would not allow its sale.
When confronted with confusing, contradictory statements from aviation officials, we would always advise our readers to kindly ask for written evidence of the purported facts or regulations. We’re happy to help set the story straight as we did in these two instances. Clarity is the first step towards progress.