The US Federal Aviation Authority (FAA) this week issued a supplemental type certificate (STC) for a 100-octane avgas that contains no lead additive.
Developed by Oklahoma-based General Aviation Modifications Inc. (GAMI), the STC for G100UL is valid for certain Lycoming O-320, O-360 and IO-360 piston engines, and has been roundly applauded by the US GA community.
“This STC is a positive step as we seek a fleet-wide solution for an FAA approved unleaded fuel,” said AOPA President and CEO Mark Baker. “We look forward to learning more about how the STC will be used, and next steps in expanding the number of engines that can safely take advantage of it.”
The search for unleaded avgas was triggered by the US EPA over 10 years ago, which demanded the additive tetra-ehtyl lead (TEL-B) be removed from 100LL (low-lead) avgas. Without TEL-B, fuel companies struggled to keep the 100 octane rating demanded by most GA piston engines.
“We commend GAMI for its hard work and commitment to producing a high-octane unleaded avgas and support its continued testing on a broader range of engines and airframes,” said GAMA President and CEO Pete Bunce.
“While this STC is a start, demonstrating the safety and viability of a high-octane fuel as a replacement for 100LL requires significant testing on high performance engines, as well as certain airplanes and helicopters at the most demanding boundary of the performance envelope encompassing the existing fleet of aircraft.”
Other companies such as Swift Fuel and Shell Aviation have been working on 100-octane unleaded avgas, but have yet to bring anything to market.