A recent story by Michael Mooney, who is an aviation fuels supplier, states that the reason that no major oil company is supplying mogas to end users is because of liability.
When it was posted, several people commented that the liability issue is a myth and that they have been selling mogas in Europe with no liability problems. Well, it is not a myth and comparing European liability laws to the US system is like comparing basketball to football. They are both sports played with a ball, but there are significant differences, like contingency cases.
There are a lot of small issues with using mogas in aircraft, but the major issues are cost/profits, misfueling by the pilot, and a window of vulnerability that involves post-crash inspection.
The cost/profit concern deals with the amount of profit an oil company can make in a single automotive fuel dealer that pumps more than 100,000 gallons per month verses the number of FBOs and the liability exposure and equipment needed to sell the same amount of fuel at airports. It is called return of investment.
With mogas in aircraft, there are a number of handling concerns, but ethanol compounds increase the problems significantly. Now that ethanol in mogas is becoming so wide spread, it is becoming more and more difficult for people to find ethanol-free mogas. This means that even if a FBO sells non-ethanol fuel, the odds are fairly good that if a pilot adds fuel they purchased elsewhere, they may mistakenly put ethanol-containing fuel into their airplane.
If a pilot does get some ethanol fuel in their plane, and has a problem, here is where the liability problem with selling mogas at the airport becomes a concern.
100LL is a bottomed, unique fuel. If a sample of fuel is left in the wreckage — even just a few drops — a quick True Boiling Point (TBP) distillation by Gas Liquid Chromatography will quickly show if the fuel was pure 100LL or contained some mogas. If there is a large enough sample, it can be tested for ethanol, but that is rare.
An even worse scenario is if no fuel is available. Now investigators are dependent on tests and inspections of the engine and fuel system. Here, all they have to do is look at the exhaust ports. If they are black, it is an indication that the plane was burning mogas and the heavy ends in the fuel left a heavy black tar-like deposit in the port. If they had been burning 100LL, then there would not be a tar-like black deposit. Even if the plane was involved in a fire, an analysis of the deposit in the exhaust port will probably tell whether any mogas had been used.
In this case, if the deposits did not show any tar-like substance, and the FBO’s 100LL fuel samples were OK, then it is in a defensible position. If there is evidence of tar or coke-like deposits in the exhaust ports, and the FBO’s 100LL fuel sample checks out OK, then it is still in a defensible position, because it proves that the pilot had been adding mogas on their own. This mogas could have contained ethanol, which could have caused the problem.
Now let’s look at an FBO that is selling mogas, and the same thing happens where the pilot adds some additional mogas that does contain ethanol and an accident occurs. Here the burden of proof shifts to the FBO, especially if there is no fuel sample available. The FBO must be able to prove that it has samples from every delivery, no matter how small, and that every sample was without ethanol and on spec.
This may not seem like a big deal and I am sure that the mogas people will say it is nothing. But this shadow or possibility of ethanol causing the problem may be enough for a good lawyer to convince a jury that the FBO was partially responsible. And since the oil companies have deep pockets, it will not hurt them any to help feed this poor pilot’s family and keep them out of the cold.
The bottom line is always, “Will the oil companies make enough money selling mogas at airports to offset the liability exposure?” Again, I would not bet the family farm on it happening.