Recognizing global concerns about the immediate and long-term availability of aviation-grade 100LL fuel, Lycoming Engines announced this week that it is working to get approval for the use of unleaded automotive gasoline for its standard-compression-ratio O-360 and IO-360 product lines. Ian Walsh, general manager for Lycoming Engines, told AVweb the approval will not require any modification to the engines, the fuel will not need any additives or special treatment, and there will be no degradation in engine performance. “It’s essentially a paperwork drill, to make this happen,” he said. He expects to have approval from the FAA by this fall, but owners cannot implement the change until the airplane also gets certified. That is up to the manufacturers, Walsh said, and he could not estimate how long that would take, but said it is also essentially a paperwork issue. The engines will require a specific type of unleaded 93 AKI automotive gas, designated as Euro Norm EN228 (in Europe) or ASTM D4814 (in the U.S.). This fuel is not difficult to find, Walsh said, but users must verify that they are getting that particular type — not just any unleaded auto gas will do.
The unleaded automotive gas is generally cheaper than avgas and provides an alternative in areas where avgas is scarce. Also, the continuing use of leaded avgas provokes environmental concerns. The popular O-360 and IO-360 engines are found on many GA aircraft, including Cessnas, Mooneys, Diamonds, and more.
