Committee reports on challenges to replacing 100LL

A just-released report from the Unleaded Avgas Transition Aviation Rulemaking Committee concludes that a drop-in replacement for leaded 100LL is not available, adding that an additional six years is needed to assess possible replacements.

Known as the UAT ARC, the committee is a collaborative industry-government task force representing aircraft and engine manufacturers, fuel producers and distributors, operator groups, aviation associations, the FAA and the U.S. Environmental Protection Agency (EPA). Over the past several years, the group studied the challenges associated with the transition to an unleaded fuel to replace 100LL and were tasked with recommending the best way to develop and deploy an unleaded fuel that would have the least impact on the existing piston-engine aircraft fleet.

The UAT ARC found that a “drop-in” unleaded replacement fuel that can be seamlessly deployed for the existing fleet of general aviation aircraft is not available and that alternative fuels require significant assessment to ensure safety.

Committee members also note that, to date, there is not a market-driven reason to move to a replacement fuel due to the limited size and specialty nature of avgas, combined with the safety, liability and expense involved with a complex approval and deployment process.

After its own review, the FAA “found the information and recommendations contained in the report to be very helpful in understanding the challenges of transitioning the piston engine-powered fleet to an unleaded avgas.”

The UAT ARC provided several recommendations and detailed action plans necessary to facilitate the development and fleet-wide deployment of an unleaded avgas. Key recommendations include:

  • Implementation of a “Fuel Development Roadmap” that identifies specific milestones in the development of an unleaded avgas;
  • Centralized testing of potential unleaded fuels at the FAA William J. Hughes Technical Center funded by government and industry contributions to generate qualification and certification data; and
  • Establishment of a collaborative industry-government initiative, called the Piston Aviation Fuels Initiative (PAFI), to coordinate implementation of the UAT ARC recommendations. The PAFI would rely on technical expertise from both the industry and government.

If the committee’s recommendations are fully implemented and funded, up to 10 unleaded avgas candidates could be evaluated at the Hughes Technical Center. Within five years, this would generate qualification and certification data to support fleet-wide certification of the most promising candidates, officials said, noting the actual transition to an unleaded avgas depends upon the level of impact upon the existing fleet and fuel production infrastructure.

That’s why the UAT ARC recommendation asks for up to six years for additional assessment and testing that may be necessary to facilitate a transition, which would include implementing approvals across the entire fleet, certification of modifications, and changes to fuel production infrastructure.

Centralized FAA testing of candidate fuels is essential to support an efficient fleet-wide qualification and certification, which is necessary for safety, those involved said. Although this is just one part early in the process, this investment by the FAA will minimize the total cost of transition for both the FAA and industry. It also helps overcome significant market barriers, which will spur industry investments needed to develop unleaded avgas and transition the entire fleet of aircraft.

In a joint statement released by the Aircraft Owners and Pilots Association, the Experimental Aircraft Association, the General Aviation Manufacturers Association, the National Air Transportation Association, and the National Business Aviation Association, the groups say they “applaud the FAA’s leadership in establishing and participating in the UAT ARC and believes the recommendations are critically important to facilitating a transition to an unleaded avgas that works for the entire fleet. It will give owners and operators added confidence that the industry is on the right path to a solution.

“The general aviation associations will continue to work with the FAA in developing, implementing and funding an unleaded avgas plan that includes the key elements outlined in the ARC’s report that are necessary to facilitate the development and deployment of an unleaded avgas with least impact upon the existing piston-engine aircraft fleet,” the statement concludes.

The full FAA UAT-ARC report, including specific recommendations and detailed action plans, is available here.

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