Powering the Piston Fleet with a New Kind of Fuel

May 16, 2016
The Piston Aviation Fuels Initiative (PAFI) is working to develop and deploy an unleaded fuel for piston airplanes to replace the 100 low-lead avgas currently used on 167,000 aircraft in the U.S. and a total of 230,000 aircraft around the world.

If all goes according to plan, operators of piston-engine aircraft will be putting a different kind of fuel in their tanks in the not-too-distant future.

That’s because a joint industry-government effort — the Piston Aviation Fuels Initiative (PAFI) — is working to develop and deploy an unleaded fuel for piston airplanes to replace the 100 low-lead avgas currently used on 167,000 aircraft in the U.S. and a total of 230,000 aircraft around the world. GAMA serves on PAFI’s Steering Group, along with the FAA, the Aircraft Owners and Pilots Association, the Experimental Aircraft Association, the National Air Transportation Association, and the National Business Aviation Association.

As a bit of background, avgas is currently the only form of transportation fuel that contains tetraethyl lead, which has historically been required to create the high-octane levels needed by high-performance aircraft engines. Piston-engine operations without adequate octane can result in engine failure. So as PAFI seeks to qualify the best fuels for use, it’s evaluating the impact of a totally new unleaded fuel on the full scope of aircraft performance and systems capability — an impressive, and extensive, process.

In 2013, the FAA requested that fuel producers submit replacement fuel proposals for evaluation. Six companies responded with 17 fuel formulations, which the FAA then evaluated based on their impact on the existing fleet, their production and distribution infrastructure, their environmental and toxicological effects, and the anticipated cost of aircraft operations. After this careful review process, just four fuels were selected for further rigorous Phase I testing.

The Phase I laboratory and rig testing looked at fuel properties and determined compatibility with aircraft materials and components. Following this testing, the FAA announced this March that it had winnowed the list further, from four to two fuels. Those two fuels, produced by Shell and Swift Fuels, will soon undergo full-scale Phase II testing in engines and aircraft, which is expected to wrap up in 2018. This testing will be critical in determining how to minimize the effect of a transition on all aspects of the existing fleet, including aircraft and operations.

If the testing goes well, the FAA will then issue a fleet-wide authorization for general aviation aircraft to use the fuels and support the development of an ASTM International Production Specification for commercialization of the avgas. This specification will allow the fuels to be accepted in the marketplace, which will determine next steps in terms of when and where fuel is available.

While there are a lot of steps in the avgas transition, the FAA deserves our thanks for keeping the PAFI program on schedule. So does the U.S. Congress, especially the House and Senate Appropriations Committees, which all recognized the importance of this transition. Congress approved $7 million in funding in Fiscal Year (FY) 2016 for PAFI, and GAMA has made it a priority to request additional unleaded avgas funding for FY 2017.

As we make this important transition to unleaded avgas, GAMA and other members of the PAFI Steering Group will continue working hard to ensure the new unleaded avgas allows the existing fleet to operate safely and reduce general aviation’s impact on the environment.

Pete Bunce is president and CEO of the General Aviation Manufacturers Association.