Flight Schools Discuss Getting the Lead Out

The recent news about the University of North Dakota returning its fleet to leaded fuel after discovering excessive valve recession in aircraft using Swift Fuels UL94 has grabbed the attention of many aircraft operators.

Meg Godlewski

Thursday, November 16, 2023 at 05:58 PM ET

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UND used UL94 for approximately four months before returning to 100LL in late October. [Shutterstock]

Key Takeaways:

The University of North Dakota (UND) reverted to leaded 100LL fuel after discovering excessive exhaust valve recession in its aircraft engines using Swift Fuels UL94 unleaded fuel, prompting an investigation by UND, Lycoming, and Swift Fuels.
Flight schools at Reid-Hillview Airport, mandated to use UL94 due to a local ban on leaded fuel, also reported valve recession and deformation issues, leading to increased maintenance costs.
In contrast, American Flight Schools reported positive experiences with UL94, noting cleaner engines, lower temperatures, no valve issues, and reduced spark plug replacement costs, despite higher fuel prices.
Swift Fuels is developing 100R, a 100-octane unleaded replacement fuel for 100LL, aiming for FAA certification by the end of 2024 to serve the higher-performance general aviation fleet.

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The recent news about the University of North Dakota (UND) returning its fleet to leaded fuel after discovering excessive valve recession in aircraft using Swift Fuels UL94 has grabbed the attention of many aircraft operators looking to use lead-free fuel. Excessive valve recession can result in blow-by that can cause an uncommanded loss of engine power, compression, and in worst cases, valve failure.

As reported by FLYING last week, UND resumed the use of 100LL after noting “exhaust valve recession” in the Lycoming engines that power its fleet of Piper PA-28-181 Archers and PA-44-180 Seminoles.