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When the Sun Sets on 100LL, Will You Be Ready?

Learn what you can do now to prepare for the changeover to unleaded fuel.

The fuel that trucks like this carry may change soon. What does that mean for you? [File Photo: Adobe Stock]
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Key Takeaways:

  • Airports are beginning to restrict 100LL avgas, mandating unleaded fuel alternatives and requiring pilots to adapt flight planning and aircraft operations.
  • Transitioning to unleaded fuel requires compatibility checks and FAA approval for both the aircraft's engine and airframe, typically via OEM service bulletins or Supplemental Type Certificates (STCs).
  • While UL94 is an existing unleaded option for some aircraft, GAMI's G100UL is a promising high-octane unleaded alternative nearing fleet-wide certification as a direct replacement for 100LL.
  • The shift away from 100LL is complex, requiring a concerted effort from regulators, manufacturers, and operators to address compatibility, health, environmental, and financial factors.
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Some airports now restrict the availability of 100 octane low-lead aviation gasoline—commonly referred to as 100LL avgas—and are mandating unleaded fuel instead. Although this practice is not common yet—and limited to a few locations—changes are coming to aviation fuel regulations. Here is what you can do now to prepare you and your aircraft for the eventual sunsetting of 100LL.

As more airfields adopt this policy, it could cause affect flight plans and significantly impact aircraft owners and pilots, especially those operating high-performance models.

Richard Scarbrough

Richard is a US Navy Veteran, A&P Mechanic, and Embry-Riddle Aeronautical University alumni. His experience ranges from general and corporate aviation to helicopters, business jets, and commercial airliners. Former owner of a 145 repair station, he currently has an aerospace product management role and is a member of the T-C-Alliance. Follow him on X (Twitter) at @RScarCo.

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