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 its fleet to leaded 100LL fuel after experiencing excessive exhaust valve recession in aircraft using Swift Fuels UL94, prompting an investigation with Lycoming and Swift.
Flight schools at Reid-Hillview Airport, mandated to use UL94 due to a leaded fuel ban, have also reported valve recession and deformation, leading to increased maintenance costs for valve replacement.
Conversely, American Flight Schools, operating a large fleet on UL94, has reported no valve issues, noting benefits such as lower engine temperatures, cleaner-burning engines, and reduced spark plug maintenance.
Swift Fuels is actively developing a higher-octane unleaded fuel, "100R," for general aviation aircraft requiring it, with anticipated certification by the end of 2024 to further support the transition away from leaded fuels.

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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.