Unleaded Avgas Effort Kicks Into Gear
Mar 18, 2022
- March 17, 2022, 5:59 PM
Members of the Eliminate Aviation Gasoline Lead Emissions (Eagle) initiative met on March 16 and 17 to get started on the coalition’s efforts to eliminate lead additives in aviation gasoline (avgas) by 2030. Aviation associations, the FAA, and industry companies and stakeholders participated in the meeting, but it was closed to members of the media. AOPA president Mark Baker and executive director of the FAA’s Aircraft Certification Service, Earl Lawrence, briefed the media immediately following the two-day meeting. “We agreed that the number-one thing that affects general aviation’s future is this issue,” Baker said. “We’re moving as fast as we can go and as safely as we can to do it.”
Pressure to remove lead from avgas comes not only from the Environmental Protection Agency, which will likely issue an endangerment finding about 100LL avgas this year, but also from communities near airports. Concerns about lead contamination have already resulted in two California Airports—Reid-Hillview and San Martin—banning the sale of 100LL. A key goal of the Eagle initiative is to meet the FAA’s desire for the development of unleaded avgas that could obtain blanket approval for any piston aircraft engine that runs on avgas. This would include the large-bore, more powerful engines with higher compression ratios that need lead or some equivalent to prevent harmful detonation. There are alternative avgas blends now available, chiefly Swift Fuels UL94 for lower-power engines and G100UL from General Aviation Modifications Inc. (GAMI), which has been tested in high-power engines and is STC’d for a variety of low-power engines. GAMI claims that G100UL is a drop-in replacement for the current 100LL avgas, and it has tested it extensively in a GAMI piston-engine test cell and found no compatibility problems with engines, fuel tanks, or avgas distribution systems. However, the STC requirement for these alternative fuels doesn’t meet the Eagle coalition’s and the FAA’s blanket approval goal. This would require a new fuel to meet an ASTM specification for no-lead avgas, and this standard has yet to be developed. Also, engine and aircraft OEMs would have to approve the new fuel to operate in their aircraft. The big advantage for a fuel with blanket approval is that no STC would be needed and thus Form 337 (major repair and alteration) would not have to be submitted to the FAA for each aircraft approved under the STC. Lawrence pointed out that the Eagle program is not replacing the FAA’s Piston Aviation Fuels Initiative (PAFI) and that PAFI remains a key part of the process. He explained that it’s not up to the FAA to certify a new fuel because the agency doesn’t have an approval process for fuels. “We certify aircraft,” he said. The aircraft and engine manufacturers specify the type of fuel required and do testing to make sure the fuel works properly in their products, as required by Part 23 and 33 of the FAA regulations. The ASTM industry-led standards process has taken on the role of approving the fuel itself. “We rely on that standard to handle the production of fuel and oils referred to [by] the aircraft [OEMs],” Lawrence noted. One way that PAFI will help the Eagle initiative is that PAFI had built a process with ASTM for blanket approval of a new fuel, when it comes along. “We’re looking at using that process,” Lawrence said. “The FAA is doing a lot of research at our tech center.”
The blanket approval process also should facilitate use outside the U.S. of whatever unleaded avgas makes it through the exercise. “We’d like to have a fuel waiting for us when we get there,” he said. The Eagle initiative is moving ahead and will hold another stakeholder meeting in the next few months.