Fixing the Avgas Lead Problem EAGLE initiative tackles toxicity of avgas.
For decades, experts have been trying to rid avgas of its lead. Added to boost octane and prevent engine damage at high power settings, tetraethyl lead, as the fuel additive is known, is quite toxic, even at very low levels.
Almost all avgas in the US market today is grade 100LL (100 octane low lead), and more than 190,000 registered piston-engine aircraft use the fuel to operate, according to the FAA. With leaded gasoline for cars banned since 1996, avgas is now the largest source of lead emissions in the United States. Creating an unleaded fuel that will deliver the same performance advantage as 100LL has thus far eluded researchers. With concern growing over
lead’s toxicity, however, the aviation industry has decided to step up its efforts to find a solution. In February 2022, the FAA announced a new
public–private initiative to eliminate lead in avgas by the end of 2030 without compromising safety and while maintaining the viability of the existing piston-engine fleet and infrastructure. Backed by leading aviation organizations, including HAI, the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative brings together stakeholders from aviation, the petroleum industry, and US government agencies to solve the complex issue of developing, testing, and certifying an unleaded fuel that is effective and safe to use, not only in piston engines but throughout the aviation fuel supply chain. “About 25% of the rotorcraft fleet is made up of piston aircraft, which are often used as trainers and by tour operators,” says Cade Clark, VP of government affairs for HAI, who serves on the EAGLE policy committee. “Removing lead from avgas is going to require a lot of work from industry and government, as well as refiners and operators. We have to ensure we put procedures in place for a safe transition. There’s going to be a gradual phaseout: 100LL isn’t going to magically
disappear overnight.” Today, only one fuel being produced, UL94, meets ASTM International specifications for unleaded avgas, according to Options for Reducing Lead Emissions from Piston-Engine Aircraft, a 2021 report by the National Academies of Sciences, Engineering, and Medicine (available online at
hai.rotor.org/cfOUry). An option for some low-performance fixed-wing aircraft and rotorcraft, UL94 is only available at a limited number of airports, likely due to the high cost of the separate storage and dispensing system required.
“[UL94] has the potential to be used in about half to two-thirds of existing piston-engine aircraft,” notes the report. “Aircraft would need to acquire FAA certification approvals to use UL94, which many newly produced aircraft do not have. However, many low-performance models are technically capable of using this fuel, and continued innovations in engine design could soon enable many future high-performance aircraft to use it as well.” Experts from the National Academies suggest that the FAA issue a Special Airworthiness Information Bulletin to permit the use of UL94 in aircraft that can use it safely today, as well as provide incentives for airports that would make the fuel more widely available.
Of course, UL94 solves only part of the
problem: creating a universal, drop-in, lead-free fuel replacement for all piston-engine aircraft remains the ultimate goal for the industry and the EAGLE initiative. Researchers need all the help they can get. “Removing the lead is the right thing to do.
We encourage others to join the EAGLE initiative, especially on the technical side,” Clark says. “We want to make sure we’re preserving operators’ right to fly by having fuel available, but we need to do our part to remove lead from that fuel. Taking a proactive stance by finding a solution is a better approach—and one way to protect the future of our industry.”
44 ROTOR JUNE 2022
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