As most pilots following the efforts to get unleaded avgas to users are aware, there was a consent judgment entered into between the Center for Environmental Health, a California nonprofit organization, and a score of FBOs and avgas distributors in December 2014. The quick summary of the agreement and court order is that it required those FBOs and fuel distributors to sell unleaded avgas as soon as it was “commercially available.” The case was filed in Alameda County, California.
Just before we went to press, we learned that the Center for Environmental Health has filed a series of pleadings to enforce the 2014 judgment and is asking that the court find the FBOs in contempt of court for failing to comply with the judgment and seeking sanctions against the distributors because a high-octane unleaded avgas, GAMI’s G100UL, is commercially available in California.
We aren’t going to try to predict the results of the current legal action, but we think it will up the ante in the delay game that EAGLE (Eliminate Aviation Gasoline Lead Emissions by 2030) has been playing for some years to keep unleaded avgas, particularly G100UL, off the market.
Now that G100UL is being sold at two airports in California and several thousand gallons of it have gone into wings of piston-engine airplanes, we are looking into what pilots and owners can expect when they start burning G100UL. We’ll then look at the safety and quality control measures in place for G100UL to protect users, sellers, distributors and anyone else in the supply chain.
Unleaded avgas is a big, complicated subject, so we’re going to have to break the subject into two parts. In the first, we’ll explore user experience and safety/quality control matters. In part two, we’ll go more deeply into the business end of G100UL, how FBOs, distributors and others will handle the fuel, the insurance situation for the supply chain and other issues and review the actions of EAGLE to date and call a stop to its taxpayer funding because its work is complete.
Background
During the month of November 2024, two unleaded avgas formulations went on sale at FBOs in California. GAMI’s high-octane G100UL went on sale at Reid-Hillview and Watsonville. Flight school San Carlos Flight Center begin using Swift Fuel’s 100R unleaded avgas for its school Cessna 172s, although we have not seen data that shows 100R is a high-octane avgas, and the 172s using it do not require 100 octane fuel.
In our considered opinion, unleaded avgas is now commercially available in the State of California
Given that G100UL has been in use in piston-powered general aviation airplanes for well over 10 years and is now commercially available, what is going on among users? Are engines quitting? Are fuel system seals giving up the ghost? Is airframe paint being melted away?
What we are learning is that switching over to G100UL is simply no big deal. We’ve heard of no fuel system or engine problems. We are getting reports that spilling fuel on the airframe will leave a light brown stain if it’s not promptly wiped up, but that if it isn’t noticed, it can be cleaned easily downstream.
The user with the most experience with G100UL is, of course, GAMI. It has run the fuel in a number of airplanes for years, notably in a turbonormalized Cirrus SR22 for some 14 years without any issues. However, as it is the creator of the fuel, it’s not exactly an objective observer.
When the FAA gives approval for something, such as an engine or airframe or fuel, there is no requirement for additional testing. We’ve looked hard at the testing required under various FAA approvals and have come to be of the opinion that it is rigorous as all hell and sometimes more so than necessary. For example, we can’t even count the number of aircraft manufacturers that ran out of money trying to complete the FAA testing requirements for certification of a new aircraft. FAA approval for the G100UL STC took 12 years.
F&R Testing
We are familiar with two aircraft manufacturers that perform function and reliability (F&R) testing on their new types of airplanes above and beyond what is required by the FAA in issuing a Type Certificate.
We were involved in the F&R testing of the Cessna 208 and T303 where we, and a team of non-test pilots (just pilots who worked for the manufacturer and were qualified to fly the airplane), flew the bejabbers out of those planes day and night over the course of a few weeks to put 100 hours on them to see what would break.
In checking around the general aviation world, all of the F&R tests we’ve run across have been 100 hours or less.
Nevertheless, AOPA did what amounted to a 200-hour F&R test on G100UL in a leased Beech Baron. It ran G100UL through one engine and 100LL through the other.
A graphic depiction of the wear metals in each engine’s oil sample (taken at 180 hours of use) is shown on the preceding page. It shows that wear metals on the engine run on G100UL were about half those on the engine run on 100LL. In our opinion, data like this will lead to longer intervals between oil changes, the use of synthetic oil and longer TBOs, a win for all piston-engine aircraft owners.
We put 3.3 hours on that Baron and reported on it in our March 2024 issue. Our results were that it simply wasn’t a big deal flying it, and that, in itself, was a big deal. We did note that because G100UL has more BTUs per gallon than 100LL, when setting the engines to the same power, the G100UL engine burned a half-gallon less fuel per hour than the 100LL engine.
A guy who flew the AOPA Baron many hours (he was with us when we flew it) is an interesting character. John Whitehead was a flight engineer on C-123 Globemasters for the Air National Guard. It had four 3,800-HP Wright R-4360 piston engines. Whitehead went on to fly for Federal Express for 40 years, but he remained a piston-engine geek after dealing with the care and feeding of some of the most temperamental piston-pounders ever hung on airframes.
He was the perfect choice to be one of the project pilots for AOPA’s unleaded fuel F&R Baron.
John Whitehead started his comments about putting time on the Baron with, “It was a ho-hum, everyday experience.” Going in, he said that he wanted the experience to be just like running 100LL and that’s what it turned out to be. He said that, as with everything in life, G100UL isn’t perfect. It can stain aircraft paint if spilled and not cleaned up, but just as people clean bug splat off of the windshield, they’ll wipe up any residue after fueling. Given what he referred to as the benefits of G100UL, doing a quick wipe around the fuel filler area isn’t a big deal.
Transcontinental
Shortly after G100UL fuel went on sale at Reid-Hillview, Palo Alto, California-based pilot Gustavo Faerman flew his B36TC Bonanza on a transcontinental trip using only G100UL. He filled up with G100UL at Reid-Hillview and burned a few gallons repositioning to Palo Alto. On November 22, 2024, he flew nonstop to Ada, Oklahoma, where he could fill up once again with G100UL. The flight took 7.5 hours and he landed with a 45-minute reserve after running at 45 to 50 percent power for maximum range.
He told us that the slightly greater number of BTUs in a gallon of G100UL over 100LL probably gave him the extra endurance over a seven-hour flight to be able to do it with satisfactory reserves.
The next day Faerman flew nonstop to Westchester County Airport, New York, in 6.5 hours.
Faerman told us that he had purchased the G100UL STC a year ago and was hoping that the fuel would be available soon and is quite pleased that he could buy it near his home base airport. Thus far he’s put over 300 gallons through his engine and told us that it’s been uneventful. With the benefits of unleaded fuel for his airplane, he commented, “Why would I want to burn leaded avgas at all?”
Once when sumping the fuel tanks, Faerman said that some fuel splashed on the underside of the wing and he didn’t notice it. He saw a light brown discoloration on the paint sometime later. He told us that it came right off when he wiped it with Simple Green.
Supply Chain Protection
We received an email from Dan Olsen, president of Sibran, an avgas provider at Deer Valley, Arizona, and Pueblo, Colorado. He expressed discomfort with G100UL because he is concerned about quality control and the lack of an ASTM spec.
Olsen told us that when he receives a load of fuel from Phillips 66, he receives a Certificate of Analysis from Phillips that shows him that the batch of fuel was tested for some 28 parameters from the D910 ASTM spec for 100LL. His personnel then take a sample of the fuel to measure the API (American Petroleum Institute) gravity of the fuel. If it is out of limits, he won’t accept it.
Olsen asked why GAMI didn’t get an ASTM spec for G100UL.
We reached out to George Braly at GAMI to discuss STC versus ASTM and G100UL quality control.
First we learned that GAMI applied for an ASTM spec in 2010 but later abandoned that effort. One of the reasons was ASTM would not allow use of enhanced test methodology (ASTM D6730 or D6733, Detailed Hydrocarbon Analysis—DHA) as one of the several means of enhancing quality control for G100UL over the QC level of 100LL.
We were advised informally, from another source, that another problem was ASTM confidentiality as, apparently, one of the ASTM members used GAMI confidential data and attempted to obtain a patent, only to find out that GAMI had already filed for one.
Under ASTM for avgas, the producer tests each batch of fuel and creates a Certificate of Analysis (C.O.A.). The producer self-certifies its own production of 100LL fuel.
Under the GAMI G100UL STC issued by the FAA, there is an additional level of security in the quality control equation. The producer has the batch of fuel tested by an independent lab instead of in-house. That lab also performs a more rigorous test, a Detailed Hydrocarbon Analysis (DHA) as defined by either ASTM D6730 or 6733 test methods.
The G100UL QC process is more rigorous than the ASTM 100LL process where the producer could ship the fuel after self-testing in its in-house laboratory. The FAA-approved production control for G100UL requires that the fuel producer send the test results, including DHA, to GAMI. GAMI reviews the test results and if the fuel meets the production specs, GAMI assigns it a General Aviation Authorization Number (GAAN) that uniquely identifies that specific batch of fuel.
Only after the test results are found to meet the FAA-approved spec does GAMI send the Certificate of Analysis—which includes the GAAN—back to the producer of the fuel. It is then legal for the producer to release that batch for sale.
When it arrives at its destination, the recipient, exactly as with Mr. Olsen’s explanation for ASTM fuels, takes a fuel sample and measures the API gravity.
The other benefit of the DHA is that it is essentially a DNA blueprint for that batch of fuel. If there is an accident and even an ounce or two of the fuel can be obtained from the aircraft, a new DHA can be performed. Even if the fuel has been commingled with 100LL, the DHA will give ratios of molecules of the fuel components that are the DNA of that fuel. That allows the NTSB to go to GAMI and identify the specific batch of fuel that was in the aircraft and see the test results of the fuel when it was produced. In our opinion, that new technology reduces liability risk for both FBOs and fuel distributors over ASTM fuel such as 100LL.
That is consistent with the FAA-approved language in the G100UL spec: “This Specification and Standard for a High Octane Unleaded Aviation Gasoline provides, not only an equivalent, but, in fact, an enhanced level of quality control of the properties and performance of the aviation gasoline produced under this specification and distributed throughout the supply chain, as compared to the traditional governmental, military, or industry voluntary consensus based standards” (emphasis added). An ASTM spec is a “consensus based standard.”
Conclusion
G100UL fuel is being sold and we’ve been advised that several thousand gallons have already been burned without problems. We’re actively seeking feedback from users.
Next month we are going to go into the business side of providing unleaded fuel, outline the objections that have been raised to G100UL and see if they can be addressed. We’ll examine whether there is a need for EAGLE’s continued existence and use of taxpayer funds.
