The FAA will issue a fleet authorization this year that will allow more than two-thirds of the gasoline piston fleet to operate on 91UL avgas. In a news conference held to update progress on the development of an unleaded high-octane replacement for 100UL, Lirio Liu, the head of certification for the FAA, said the agency plans to issue the blanket approval as part of the initiative to get rid of lead in avgas. “We expect approximately about 68 percent of the general aviation fleet will be able to use the UL91.”
In addition to reducing lead emissions from piston aircraft, the fleet authorization for UL91 will give a glimpse of a lead-free future for GA aircraft. “That will facilitate broader use and experience with the transition,” Liu said.