RUDDER & WRENCH UNLEADED FUELS / Gold at the end of the tunnel When will G100UL come to a fuel pump near you? GEORGE BRALY, CO- FOUNDER of General Aviation Modifications Inc. (GAMI), holds out a beaker and invites a visitor to waft it toward her nose. " Can you smell the difference between that and 100LL? " he says. " People say it's got a sweeter smell. " People are right. This unleaded aviation gasoline-gold in color, tagged with the name G100UL-does have a slightly different odor than the blue 100LL we've all come to know. It is the result of nearly 10 years of development, testing, and certification. In 2021 the FAA granted its developer supplemental type certificates that allow the fuel to be used on hundreds of piston aircraft-representing about 70 percent of the overall fleet. However, the remaining 30 percent of aircraft not covered by the STCs use 100 octane fuel and account for 80 percent of all avgas utilization. According to Braly, the FAA's Aircraft Certification Office in Wichita acknowledged via email that GAMI completed all certification requirements for the use of the fuel in all spark ignition engines and the aircraft that use them. Still required is an official FAA signature on an expanded available model list supplemental type AOPA PILOT / August 2022 93 DAVID TULIShttp://efirc.com/pilot