Here's what Petersen Aviation has to say about their STC At this time, ethanol cannot be legally or safely used with the STC's. Fuel containing MTBE or ETBE is acceptable. Therefore fuel blended to D-439 or D-4814 without alcohol, is acceptable and legal for use with the STC's. If your state does not require compliance to
Here's EAA's take on it. If alcohol content is less than 1%, fuel will probably have no effect on aircraft. If fuel contains up to 5% alcohol, caution must be exercised. Do not permit it to remain in tanks or fuel system for more than 24 hours, then drain and refill with alcohol-free fuel, ensuring that no alcohol concentration remains in fuel lines or sump. Vapor lock may be a problem. DO NOT FLY. If alcohol content is more than 5%, DO NOT FLY. Drain the fuel system, flush all parts, replace with clean alcohol-free fuel and run up engine long enough to exchange fuel in carburetor bowl. It looks like EAA will allow only 1% and Petersen 0% alcohol in the fuel to remain in compliance with their STC. Cheers: Paul N1431A KPLU
