In what is being hailed as a milestone for general aviation, the FAA has approved an extension of a Supplemental Type Certificate (STC) that allows unleaded fuel developed by General Aviation Modifications Inc. (GAMI) to be used by the entire general aviation fleet. .
Known as G100UL, the fuel was initially approved in July 2021 for a limited number of engines, including the Lycoming O-320, O-360 and IO-360 piston engines. With the recent nod from the FAA, the list of approved models now covers “all spark-ignition piston engines and every airframe using a spark-ignition piston engine in the type certificate database of the FAA”.
The approval comes after more than 12 years of testing, and more testing, and more testing, by the FAA to ensure the fuel was safe for general aviation use.
“The FAA told us that this was the most thoroughly tested and documented STC ever performed at the Wichita Aircraft Certification Office,” said George Braly, co-founder and chief engineering officer of GAMI.
“It’s a great day for GA,” added Tim Roehl, president and co-founder of GAMI. “Not only can we look forward to an unleaded fuel future, but the benefits of G100UL will improve the maintainability and reliability of our engines, improving dispatchability and safety.”
According to Mark Baker, president of the Aircraft Owners and Pilots Association, the FAA’s approval of the use of G100UL fuel in all piston-powered aircraft fulfills the industry’s long-standing goal of finding solutions that can be used for the entire fleet of GA pistons.
“I’m proud of GAMI, the industry team, and the FAA for persevering over the long haul and achieving a fuel that the FAA has recognized as a viable low-lead alternative,” he said. -he declares. “It is vital that we find solutions to what has plagued general aviation since the 1970s. This is certainly the biggest problem I have faced during my time at AOPA.
“It’s a big deal,” he added, “but there’s still a lot of work to do.”
When will it be at your airport?
The plan is for GAMI to license fuel formulation to oil refineries. The license includes a quality control aspect that allows GAMI officials, as well as FAA officials, to perform random inspections to ensure the fuel is properly manufactured.
It has also entered into an agreement with Avfuel to manage fuel distribution logistics, with the two companies committing to “ensure that G100UL avgas is available to all legitimate distributors and sellers on an equitable basis”.
At SUN ‘n FUN 2022, Braly noted that the first customers for the G100UL will be airports where the 100LL has been banned, such as Reid-Hillview Airport (KRHV) in East San Jose and San Martin Airport ( E16) in Santa Clara County, California.
Global politics, including the war in Ukraine and ongoing supply chain issues, will also impact when new fuel might arrive at your airport, Braly noted.
“It’s going to take some time to manage the infrastructure, including manufacturing and distribution,” Braly said. “Supply chain is still a very damaged infrastructure and it’s not going to make the process any easier, but we know how to do this, and with the support of the major players, I think we can do it. It’s going to be limited at first. , but it can be sped up quickly.
Although the cost of the fuel is not known – and will not be set by GAMI – Braly acknowledged that the initial small-batch production process means the fuel will cost upwards of 100 LL.
“Small batches cost money,” he said. “Until we can ramp up production to produce millions of gallons at a time, there will be an additional cost.”
“It won’t be unreasonable,” he added. “Pilots in America will not pay what they pay for avgas in Europe today.”
Owners can also expect to see engines that run more efficiently.
“I think the days of cleaning spark plugs every 50 hours are going to be behind us for good,” Braly said.
The big questions
GAMI officials know that pilots and aircraft owners have a lot of questions about the transition to unleaded fuel, so during SUN ‘n FUN, they offered answers to the most common questions they get asked.
How much is it going to cost? The best estimate is that it will cost between 60 and 85 cents more per gallon than 100LL.
Will this work on my plane? The STC covers all spark-ignition piston engines in the FAA’s type certificate database “without exception,” according to Braly. The STC is 18 pages long and includes over 1,800 engine makes and models.
What is the octane of the G100UL? In FAA-approved detonation tests, G100UL was the same – and in some cases exceeded – 100LL, according to GAMI officials. Operationally, the G100UL is virtually identical to the 100LL and actually has a little more power (BTU/gallon) for increased aircraft range, the officials added.
Will the operation of my engine change? No.
Can I mix G100UL and other fuels? Yes. In fact, you can mix G100UL with any fuel approved for your aircraft, in any ratio.
Besides being lead-free, does G100UL have any other benefits? Spark plug maintenance and replacement intervals will improve with the absence of lead, while oil change intervals are likely to double over time. Without lead, synthetic oil is also likely to become available, which will further increase oil change intervals, GAMI officials said.
What if I fly a warbird? It will also work in your aircraft. The STC includes all WWII engines and all post-WWII radial engines.
What modifications will I need to make to my aircraft? You will need to attach a small plate to the engine and add a short rider operating manual supplement. That’s it.
How much will the STC cost? Pricing will be based on engines and horsepower, similar to the pricing of other fuel STCs. For example, the Experimental Aircraft Association’s STC for automotive fuel is $1.50 per horsepower. Petersen Aviation offers its STC for $2 per horsepower.
Other companies are also involved in the transition to unleaded general aviation, including pioneering Swift Fuels, which has received FAA approval for its 94-octane unleaded fuel. It is available in a number limited number of airports, with a concentration on the West Coast and around Indiana, where the company is based.
Swift Fuels’ 94-octane fuel meets some, but not all, of the demand for aircraft with low-compression engines, AOPA officials noted. The company is developing 100R unleaded fuel with over 10% renewable content.
Additionally, two candidate fuels are currently undergoing the FAA’s Piston Aviation Fuels Initiative (PAFI) testing process.
“We would like to see multiple fuels available that all work together and blend together,” said AOPA’s Baker. “Competition is always good for markets.”