For Commemorative Air Force (CAF) member Patrick Mahaffey, any day spent flying a vintage World War II aircraft is special. Recently, however, Mahaffey experienced a flight that was not only special but also historic. He became the first pilot to fly a large radial engine airplane using the new unleaded aviation gasoline.
This landmark flight involved the CAF Sierra Hotel Sponsor Group 1944 A-26 Invader attack bomber, a powerful aircraft with a 2,000 HP radial engine. During the flight, the aircraft operated on two different types of gasoline. The right engine used the newly developed unleaded aviation fuel, while the left engine continued to use the traditional leaded gasoline that has been the industry standard for decades. According to Mahaffey, there was no noticeable difference in engine performance despite the use of two different fuels. A-26C 44-35643 (N626SH) was built at the Douglas Plant in Tulsa, Oklahoma. Initially, it served as a stateside trainer for A-26 combat crews until the end of WWII. After the war, it was converted to the RB-26C configuration and later sold to the French Air Force, where it flew combat reconnaissance missions in Indochina for 18 months. After its service with France, the aircraft returned to the U.S. and was converted into a corporate transport, flying in the U.S. and Canada before being acquired by the CAF. Following a landing mishap, it was grounded for 28 years, with 22 of those years spent in restoration by Sierra Hotel. In 2020, it finally returned to the skies over Oklahoma!
This flight marks a significant milestone for the entire aviation community, particularly in relation to the Federal Aviation Administration’s (FAA) efforts to eliminate leaded aviation fuels. Following a Congressionally mandated report from the National Academies, the FAA, in partnership with the aviation community, launched the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative. The EAGLE team aims to safely phase out leaded aviation fuels in piston-engine aircraft by 2030.
To achieve this goal, the FAA established two pathways to authorize new unleaded fuels: the FAA fleet authorization process and the traditional aircraft type certification/supplemental type certification (STC) process. As part of the STC process, the FAA approved a model list STC in September 2022 for GAMI’s 100 Octane unleaded fuel (G100UL) for general aviation aircraft. The FAA is also working with Swift Fuels on an STC for a high-octane unleaded fuel (100R) for a limited number of engines and aircraft, expected later this year. In March 2023, the FAA issued a Fleet Authorization Policy Statement to guide the authorization of unleaded fuels for the U.S. piston-engine general aviation fleet. The FAA plans to issue fleet authorizations for UL 94 / UL 91 unleaded fuels later this year, making approximately 68% of the general aviation fleet eligible to use these fuels.
Under the Piston Aviation Fuels Initiative (PAFI), the FAA is collaborating with Afton Chemical/Phillips 66 and LyondellBasell/VP Racing to test and evaluate high-octane unleaded fuel solutions. Fleet authorizations for these fuels are expected after successful testing. To support flight schools, the FAA and EAGLE have developed a guidance document to aid with the transition to unleaded fuels. Additionally, the Airport Cooperative Research Program is developing best practices for the safe transition to unleaded fuels for the country’s fleet of 220,000 piston aircraft.
Patrick Mahaffey’s historic flight not only marks a significant achievement in aviation fuel development but also brings us closer to a future where unleaded aviation gasoline is a reality for all pilots and airplanes. This flight, combined with the ongoing efforts of the FAA and the EAGLE initiative, highlights a pivotal moment in the journey toward a lead-free aviation future. Check out the FAA’s entire plan to build an Unleaded Future by 2030 here
Born in Milan, Italy, Moreno moved to the U.S. in 1999 to pursue a career as a commercial pilot. His aviation passion began early, inspired by his uncle, an F-104 Starfighter Crew Chief, and his father, a military traffic controller. Childhood adventures included camping outside military bases and watching planes at Aeroporto Linate. In 1999, he relocated to Atlanta, Georgia, to obtain his commercial pilot license, a move that became permanent. With 24 years in the U.S., he now flies full-time for a Part 91 business aviation company in Atlanta. He is actively involved with the Commemorative Air Force, the D-Day Squadron, and other aviation organizations. He enjoys life with his supportive wife and three wonderful children.
The unasked question is how many aircraft engines currently have unhardened valve seats and valves? Are we going to repeat the unleaded fuel debacle that we went through with wheeled vehicles?