FAA seeks feedback on unleaded fuel transition

The FAA emphasizes that the document is not a regulation or mandate, but a framework intended to support a safe and orderly transition for piston-engine aircraft and the aviation industry.

The transition plan was developed as part of the FAA’s work with the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative, a government-industry partnership focused on addressing the long-term transition away from leaded aviation fuel, of which AOPA is a founding member.

“The FAA notes that stakeholder feedback will further inform the transition moving forward. Stakeholder participation will also support transparency and keep safety at the forefront,” according to a statement from EAGLE. “EAGLE urges all aircraft owners and pilots to review the draft Transition Plan and submit comments focused on safety, feasibility, and operational needs.”

The draft proposes a phased approach to eliminating the use of low-lead fuel by the end of 2030 for most of the country, with an extended timeline for Alaska until 2032, which would occur in four phases:

• Phase 1: Fuel authorizations and comparisons
  The FAA works to complete approvals for candidate fuels and publishes testing data so pilots, aircraft owners, and the industry can understand how they compare.
• Phase 2: Gaining market experience
  Early adopters begin using unleaded fuels while the industry works to make them available and addresses the supporting infrastructure needed.
• Phase 3: National transition (for the contiguous United States)
  With unleaded fuel widely available—and with nearly all piston-engine aircraft and engines authorized or modified to use it—the contiguous United States transitions away from 100LL.
• Phase 4: Alaska transition
  Alaska is expected to transition after the rest of the country because of the state’s unique fuel supply and operating challenges.

“It’s important to recognize we’re still early on in this process, but we need to understand what this transition will look like,” said AOPA Vice President of Regulatory Affairs Murray Huling. “A lot of people think that 2030 is a hard deadline, but it’s better to think of it as a goal. This plan is a draft, and as it changes or if any part of the final plan shifts, that date could change.”

Currently, three unleaded fuels are in various stages of obtaining FAA authorizations or approvals through two different pathways:

• Fleet authorization
• Receiving a fleet authorization allows for an unleaded fuel to be used across a group of aircraft and engines at once. This work is being done through the Piston Engine Aviation Fuels Initiative (PAFI), which is a collaborative effort between the FAA and the aviation industry.
• UL100E, which is being jointly developed by VP Racing and LyondellBasell, is the only candidate fuel being evaluated through the PAFI process. The companies expect to receive an ASTM production specification and FAA fleet authorization in early 2027.
• Aircraft type certificate (TC) or supplemental type certificate (STC)
• The FAA may issue TCs and STCs for individual aircraft and engine types or multiple aircraft and engines through an approved model list.
• 100R, developed by Swift Fuels, has received STCs for use in Cessna 172R and 172S models, in addition to receiving an ASTM production specification in September.
• G100UL, developed by General Aviation Modifications Inc., has received an STC with an approved model list that covers virtually all piston-engine airplanes, and is working to expand that to helicopters. However, it has not sought or received an ASTM specification.

Despite pursuing different authorization pathways, VP Racing/LyondellBasell UL100E and Swift 100R have also sought and received different specifications from ASTM International, which develops consensus technical standards that are used in a wide variety of industries worldwide.

“ASTM specifications have been an important part of this process,” said Huling, who represents AOPA at ASTM meetings. “It requires manufacturers—and, in this case, fuel providers—to adhere to clear requirements to make sure their products meet specific safety, performance, and compatibility standards.”

The FAA is also performing comparative testing “under identical conditions to allow direct comparisons between fuels,” and may test the ability to mix the fuels.

“There will be significant operational challenges and risks if multiple fuels are authorized for the same aircraft but cannot be mixed,” the plan states. Such a scenario could segment the market and hamper the transition, and increase the risk of misfueling, which would raise safety concerns.

However, as testing and approvals continue, the FAA transition plan points out there are still some unknowns.

“The FAA provides a lot of detail about the work being done now, but we still don’t know how this will impact every pilot and aircraft,” said Huling. “At the very least, every aircraft will need a new placard detailing any fuel limitations and updates to your aircraft flight manual. But, depending on which fuel or fuels ultimately see widespread distribution, owners may also need to make alterations to their aircraft.”

While no specific alterations have been specified, the FAA says those “could be more in-depth, requiring engine hardware modifications such as replacement of an engine, installation of new engine pistons, the installation of anti-detonation injection systems, ignition timing changes, or significant changes to operating limitations.” The FAA is accepting public comments on the transition plan through March 13.