Analysis of using unleaded Avgas  The announcement last October by the University of North Dakota (UND) flight school that it was terminating its year-long test of Swift UL94 unleaded avgas and returning to 100LL came as a shock and disappointment to many in the industry. UND's maintenance director cited evidence of "significant" exhaust valve/seat recession in some of its Lycoming-powered Piper Archers. Is this a major setback for piston GA's transition to unleaded fuel? In this webinar, Mike Busch explores what we know about valve recession and lead, and discusses how much of an issue this is likely to be.    This webinar will be a one and one half hour presentation.