LAKELAND, Florida—Representatives of organizations representing manufacturers, aircraft owners, pilots and aircraft modification companies are grappling with the issues involved with getting the lead out of all aviation gasoline.

At press conferences during the Sun ‘n Fun Aerospace Expo in Lakeland, Florida, the executives said they expect the U.S. Environmental Protection Administration (EPA) will issue a finding in 2022 that 100-octane low-lead (100LL) aviation gasoline endangers the public. That would trigger a rule-making process that would likely result in 100LL being banned by 2030.

“This is an international problem,” Jack Pelton, CEO of the Experimental Aircraft Association, said of eliminating lead from aviation gasoline. “This is not just a U.S. problem. It’s going to impact the entire world.”

The endangerment finding will trigger a rule-making process that will result in a public comment period and will end with 100LL being banned in the U.S. “There is no way that the EPA is going to reverse course,” Pelton added.

In addition to finding a lead-free, high-octane fuel that can be used safely in piston aircraft that now require 100LL, a replacement must be something refiners can make without drastic changes to their plants and processes, fit into the distribution structure and storage at fixed base operators and not cause problems with aircraft systems outside of the engine, including fuel tanks and lines on aircraft. In addition, a replacement fuel might be compatible with an engine but due to detonation characteristics cause vibration problems in combination with an aircraft’s prop.

“If it was simple, it would have been done many years ago,” said Mark Baker, president of the Aircraft Owners and Pilots Association. “There simply has not been a drop-in solution that’s been competitively priced.”

Peter Bunce, president and CEO of the General Aviation Manufacturers Association, noted that the only plant in the world that makes the lead-based additive that is used to boost the octane of 100LL is located in Liverpool, England. The greatest threat to the piston market is if the plant ceases operation before a 100LL substitute reaches the market.

“If we don’t find a silver bullet, we’ll have to go with lower octane,” Bunce said. Some aircraft that now must run on 100LL might be able to use a fuel at a slightly lower octane, such as 97 or 98, if an unleaded replacement for 100LL cannot be found.

Officials of General Aviation Modifications Inc. (GAMI) said at their own Sun ‘n Fun press conference they expect the 100-octane unleaded avgas, called G100UL, that the company developed will be approved for all spark-ignition piston engines and the aircraft they power in time for the Experimental Aircraft Association’s AirVenture 2022 in late July. Officials from the FAA’s Wichita flight standards office have drafted the supplemental type certificates to allow the fuel’s use throughout the piston fleet, says GAMI Chief Engineer George Braly. 

The STCs would expand the approved engine and airframe model lists covered by STCs that were issued last July. Those 2021 STCs covered a limited number of Lycoming engines and Cessna airframes.

Braly says refinery modifications for making G100UL involve simple piping changes and addition of a few valves. The fuel can be transported on current tanker trucks and stored in tanks at airports that already contain 100LL without any modifications. That should simplify the logistics of distributing the new fuel. He says the fuel also has been tested in Cirrus Design’s fiberglass epoxy fuel tanks and proven not to have any negative effects.

Braly also says maintenance issues caused by leaded fuel will not be a problem with G100UL.

But while the fuel may win FAA approval for use in all spark-ignition piston engines, manufacturers of engines, props and aircraft may not honor warranties on equipment that uses the STS-approved fuel. That could leave aircraft owners with warranties reluctant to use it and some fixed-base operators unwilling to sell the fuel.

An engineering staff member of one engine manufacturer says companies will want to ensure that G100UL’s detonation and other properties do not cause problems with their systems. They will want to test G100UL before declaring it OK to use and in compliance with warranties.

The first airports to get G100UL are expected to include northern California airports where leaded fuel has been banned.