Four Fuels Under Evaluation During The First Half Of This Year

The FAA is continuing to work on a drop-in replacement for 100LL avgas through the Piston Aviation Fuels Initiative (PAFI). Through the first half of this year, the FAA has conducted testing at the William J. Hughes Technical Center of an optimized Shell fuel, and screening testing of 3 fuels not previously part of the PAFI program. The scope of PAFI has continued to evolve with the preliminary evaluation of 3 other fuels representing PAFI's commitment to research and evaluate all candidate unleaded fuels. Test results with the optimized Shell fuel were not successful with testing indicating additional refinements are required.

Test results of that engine testing have revealed that additional refinement will be necessary to support continuation and ultimately result in successful completion. Shell has indicated it is committed to additional R&D efforts to make those adjustments in order to result in a safe and viable unleaded avgas.

PAFI's test experience which brackets engine, aircraft, materials, and toxicology has served to accentuate the extent of the challenge to identify an acceptable unleaded fuel for general aviation. Accordingly, it is recognized that the scope of PAFI must expand to support the necessary research and development while engaging other candidate fuels for evaluation. The FAA alternative fuels program for general aviation must be multi-faceted, ongoing, and supported by a collaborative government and industry process. The focus remains qualification and authorization of an acceptable unleaded fuel and the safe transition to a more environmentally friendly aviation fuel.

The Piston Aviation Fuel Initiative includes four key elements –

Fleet-wide Authorization Qualification Test Program

Based on the recommendations of the Unleaded Avgas Transition Aviation Rulemaking Committee, FAA established a fleet-wide authorization test program to identify and deploy a safe unleaded avgas with the least impact on the U.S. fleet of over 170,000 piston-engine aircraft. Congress fully funded this 5-year test program in which 17 fuel formulations from a government Screening Information Request (SIR) submitted to FAA in 2014 were evaluated and down selected to the most promising candidates through technical assessments, Phase 1 laboratory and materials compatibility tests, and current phase 2 full-scale aircraft engine and aircraft testing.

Despite this recent program delay, the PAFI program is essential to ensure a viable, safe, and economical fuel can be authorized by FAA for use by the existing GA piston engine aircraft fleet.

New Alternative Fuel Proposals & Certification

Several companies continue to invest in R&D of alternative fuels and are working directly with FAA on applicable safety standards and guidance for means of compliance and qualification testing during development.

FAA invites fuel producers that are currently developing high-octane unleaded fuels to bring their data to the FAA for evaluation and initial screening to be conducted by the William J. Hughes Technical Center. Those that pass the initial screening are invited to participate in a Cooperative Research and Development Agreement (CRADA) testing program in which producers provide additional resources and some funds for independent testing using PAFI developed standards and guidance. This is an ongoing activity necessary to support FAA and industry understanding and qualification for the authorization of any newly developed and proposed alternative fuels.

Establishment of FAA safety standards

There are significant and unique challenges in evaluating performance, operability, and compatibility of any new alternative fuel to an existing fleet of aircraft and engines.

FAA research is necessary to apply existing and create new regulations, guidance and procedures for safety qualification and authorization approval to use a new fuel and the establishment of consensus fuel specifications that the FAA relies on for aircraft continued operational safety. This is an ongoing activity necessary to address FAA safety requirements for any proposed changes to fuel specifications, new alternative fuel proposals submitted to FAA, and continued operational safety activities related to a transition to an alternative/replacement fuel. The FAA Reauthorization Act of 2018 (HR 302), Section 565 Aviation Fuel, provided the Administrator with additional authorization for safety qualification and allowing the use of a replacement unleaded gasoline.

Safely Deploy and Transition to a new fuel

While it remains a challenge to identify an unleaded fuel formulation that will take the place of 100LL, the FAA and industry will continue to collaborate in executing an informed and safe transition of the GA fleet to an unleaded avgas once it is approved. The PAFI Deployment Guide will eventually serve as a roadmap to successfully deploy an unleaded avgas, from the refineries to the wingtips of aircraft, including the essential supporting infrastructure.

Nine aviation sectors have been identified as being crucial areas in need of planning and guidance, prior to deployment, including:

• State and Federal Legislative
• Aircraft Fuels Regulations and Standards
• Manufacturing Capability
• Distribution System
• Airports
• Aircraft Modifications
• Communication & Training
• International Communication
• Safety Assurance

A PAFI Deployment Guide is being drafted with the objective of providing requirements and guidance to all stakeholders affected by deployment. The Deployment Guide provides specific action plans with responsibility for each of the 9 aviation sectors and is intended to be applicable to any unleaded fuel meeting the FAA requirements for approval.

The PAFI Deployment Guide is intended to be inclusive, relative to any candidate unleaded fuels. Identifying, testing and eventually authorizing a fleet-wide unleaded avgas solution remains a difficult challenge — but one that the FAA and industry are completely committed to. The FAA and industry members of the PAFI Steering Group continue to work with multiple fuel offerors to find the very best unleaded avgas solution for the GA fleet. The resolve to find an environmentally friendly solution has not wavered — regardless of the amount of time and effort it may take to achieve.

(Source: FAA. Image from file)

FMI: www.faa.gov/about/initiatives/avgas