I have been using UL91 unleaded Avgas legally on my Certified Lycoming 180 powered light aircraft for years in the South of England.In my opinion the engine is happier on the unleaded fuel than the occasions when I revert to leaded.Its not going to be an issue for the vast majority of the GA fleet and the warbirds etc can afford to fund specialist stocks of fuel. Regards Stampe
Fly Safe considerate and compliant !