Centennial Airport Unleaded Aviation Fuel Program

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Centennial Airport is the first, and only, airport in the state of Colorado to offer unleaded Avgas. As part of the resolution passed by the board of commissioners, the airport will reimburse flight schools and airport-based aircraft owners up to $110 of the cost for obtaining an STC through 2024. In addition, the airport will work with fuel suppliers on the airport to subsidize the final cost difference between UL94 and 100LL.

Swift Fuels has an online database to confirm eligibility and they are able to provide STCs for eligible aircraft.

Aircraft owners are encouraged to fill out the online form available here for quickest processing. In addition, aircraft owners may bring in receipts to the ACPAA office at 7565 S. Peoria St. during regular business hours (Monday through Friday from  8:30 a.m. to 4:30 p.m.). 

Simplified, UL94 is an FAA-approved alternative fuel that is considered an alternative to 100LL for some aircraft.

More specifically, UL94 is a 94+ Motor-Octane aviation gasoline without Tetraethyllead that meets the ASTM D7547 Unleaded Avgas specification. UL94 is also rated as a super-premium ethanol-free auto-gasoline with a 99 octane (R+M)/2 rating that meets and exceeds the ASTM D4814 autofuel specification.

UL94 Unleaded Avgas has an identical density to 100LL, meaning weight and balance calculations will not change by using UL94. UL94 weighs 5.9 pounds per gallon: identical to 100LL.

UL94 Unleaded Avgas is currently colored clear (“water white” as defined by ASTM International) and smells like a mild version of 100LL, which is less pungent than Autogas which typically has about 25 – 50% aromatics.

UL94 Unleaded Avgas, if stored properly, has a very long shelf life – at least as long as 100LL, or even longer. A recent UL94 sample - stored in a sealed airfield tank for over 5 years - was retested in the lab and was still on-spec to ASTM D7547 Grade UL94.

UL94 Unleaded Avgas satisfies the minimum octane requirements of over 125,000 aircraft (66% of the US piston fleet) as a "Drop-in Ready" Unleaded Avgas. It requires no modifications and no hardware changes.

Source: swiftfuelsavgas.com

Yes. If your aircraft (engine and airframe or rotorcraft) is approved to use Swift Fuels UL94, then you can intermix UL94 with 100LL at any ratio. For the past 7 years, UL94 has been FAA-approved via STC, it has a full ASTM International Production Specification (D7547), and it has received many OEM endorsements. Please recognize that the benefits of using our unleaded fuel (no fouling, clean exhaust, cleaner oil, etc.) are primarily realized when 100% UL94 Avgas is in use. Please also check engine OEM recommendations of the use of synthetic (additized) engine oils outlined on our website. UL94 unleaded avgas is now approved for over 70% of the US piston fleet -- including the recent addition of 15 Continental engine models previously approved for 91/96 avgas. 

Source: swiftfuelsavgas.com

No - this is not advisable at this time. Swift Fuels has not seen the final FAA-Approved fuel blends of G100UL and there is no approved ASTM fuel specification. This is not normal protocol. Swift Fuels accepts the principle that all “Qualified” aviation gasolines sold in the US market and endorsed by OEM’s must have an ASTM Production Specification. Be advised that across the nation: 100LL Avgas, UL94 Avgas, Jet Fuel, SAF Jet Fuel, and Autogas all have ASTM Production Specifications. Swift Fuels believes the FAA does not have regulatory authority to waive-off industry and/or disallow the need for an ASTM Production Specification for any commercially available aviation fuel. It is Swift Fuels’ understanding that - according to the GAMI website and video reports – G100UL does not have an ASTM Production Specification, and does not plan to have one. Accordingly, at this time we do not advise the commercial blending of G100UL fuel in any aircraft fuel system using Swift Fuels’ products until its fuel safety can be confirmed. As these facts might change, we will be monitoring these matters closely and will be updating our website as appropriate to inform our stakeholders. 

Source: swiftfuelsavgas.com

Yes. 100LL will still be made available at APA. The process of introducing 94UL and any subsequent unleaded fuels will take time and Centennial Airport wants to make sure all based aircraft are able to operate safely from APA.

Swift Fuels has an extensive FAQ page available here.