Boulder Municipal Airport has begun offering UL94 unleaded avgas, moving a previously announced leaded-fuel transition plan into operation several months ahead of the timeline officials outlined earlier this year.
UL94 Now Available
The first 1,800 gallons of Swift Fuels UL94 arrived at the airport July 1. The fuel will be offered alongside 100-octane low-lead avgas, and a Colorado Department of Transportation Division of Aeronautics grant to the City of Boulder will allow UL94 to be sold at the same price as 100LL. Aircraft operators must have the appropriate FAA supplemental type certificate to use UL94, and Boulder plans to reimburse STC costs for aircraft based at the airport.
“We anticipate that up to 70% of the aircraft based at Boulder Airport could use Unleaded UL94 avgas, and several operators such as the Soaring Society of Boulder have already committed to switching to Unleaded UL94,” Andrew McKenna, president of Journeys Aviation, said. “Within the next year, we anticipate bringing Swift’s 100R unleaded avgas to Boulder, a fuel that is expected to be approved for 100% of the piston powered fleet of aircraft.”
Transition Plan Advances
The airport previously submitted a state-mandated plan calling for unleaded avgas to be available as early as late 2026. At the time, the plan did not identify a specific fuel or the final infrastructure and funding details. The July 1 delivery makes UL94 the airport’s first unleaded avgas offering under that transition effort.
Boulder is one of several Colorado airports moving ahead on unleaded avgas as the FAA’s Eliminate Aviation Gasoline Lead Emissions initiative targets a national transition by 2030. Centennial Airport began offering UL94 in 2023, and Rocky Mountain Metropolitan Airport has also added the fuel. Boulder officials have said future plans could include a dedicated self-service tank for unleaded avgas as fuel approvals, airport demand and state requirements continue to develop.
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