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Unleaded AvGas
NewsUniversity of North Dakota Stops UL94 Use Following Valve Recession Concerns
UND has gone back to 100LL from UL94 after citing an issue with “exhaust valve recession” in the Lycoming engines that power its fleet.
Meg Godlewski![](https://www.flyingmag.com/uploads/2023/11/shutterstock_1853809516-scaled-e1699658148323.jpg?auto=webp&auto=webp&optimize=high&quality=70&width=1440)
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