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Lycoming Engine’s UL94 Valve Seat Recession Investigation Update
WILLIAMSPORT, PA – In June 2023, the University of North Dakota (UND) Aviation program transitioned its fleet from 100LL to use UL94, a 94-octane unleaded fuel. In October, after logging 46,000 hours using UL94, UND identified abnormal valve seat recession in its Lycoming engines. Following a risk assessment, UND announced its decision to revert back to 100LL. Lycoming Engines conducted a root...