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Lycoming Releases Update on Investigation Into Use of UL94 Fuel

In a significant development impacting piston-engine aircraft operations, Lycoming Engines has released an update on its investigation into valve seat recession observed in engines using UL94 fuel. The inquiry was sparked by the University of North Dakota (UND) Aviation program’s experience after switching its fleet to UL94, a 94-octane unleaded fuel, in June 2023. Despite initial positive outcomes, UND detected abnormal valve seat recession after logging 46,000 flight hours with the new fuel, prompting a return to the traditional 100LL avgas in October.

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