Colorado’s Rocky Mountain Metropolitan Airport became the latest in the state to offer unleaded aviation fuel in February through Sheltair Aviation. The airport, one of the state’s busiesst general aviation fields, added Swift Fuels UL94 as an alternative to 100LL.
The move followed community concerns about lead emissions and comes with a state-supported price subsidy intended to keep unleaded avgas at the same retail price as leaded fuel. According to RMMA’s transition materials, the airport is also reimbursing eligible aircraft owners up to $115 for the Supplemental Type Certificate required for approved aircraft to use the unleaded avgas.
The rollout is so far limited by aircraft eligibility and fuel certification requirements. RMMA’s transition plan estimates that about 20% to 25% of its piston-engine fleet, or roughly 75 to 100 aircraft, can currently use UL94 either directly or with an STC, while 100LL is expected to remain available during the phased transition due to federal and fleet constraints.
Centennial Airport spokesperson Samantha Blymyer said her airport launched a similar program recently as well.
“There’s definitely some challenges that we’ve seen with the use of it,” Blymyer told The Colorado Sun. “Naturally, you get a little bit of hesitation from pilots wanting to make the switch.”
She said some pilots reported engine overheating while using unleaded fuel during hot summer months.
The move comes as questions about aviation lead exposure remain active in both public discussion and litigation. The Colorado Sun reported that a Colorado Department of Public Health and Environment analysis found children living near airports had higher-than-average blood lead levels.
Acording to the study, lead emissions from aircraft using leaded avgas had “a small but statistically significant effect” on children living near airport locations in Colorado.
The same report said a lawsuit brought by Boulder County and the town of Superior over lead pollution will continue in part after a recent appellate ruling.
Bri Lehman, a area resident active on the issue, told The Colorado Sun that the issue is an important one for the community.
“I couldn’t know something like that and then ignore it,” Lehman said. “It was sort of an invisible public health crisis.”
More broadly, the FAA plans to eventually transition the American GA fleet to unleaded avgas. It published a draft transition plan in January that sketches out a phased national path away from leaded avgas by the end of 2030, although it left key questions unresolved about fuel availability, cost, infrastructure and enforcement. The FAA described the process as a “safe and orderly” shift, but also made clear that the document is “not a final rule” and that the details of how a nationwide phaseout would work are still to be defined.
