TCM Flies Bonanza on Unleaded Aviation Fuel
With pressure increasing on the Environmental Protection Agency to mandate elimination of tetraethyl lead from avgas, Teledyne Continental Motors (TCM) has stepped up research into alternative fuels for aircraft piston engines. Last month, TCM and Hawker Beechcraft conducted test flights of a Beechcraft G36 Bonanza powered by a 300-horsepower Fadec-controlled IO-550 engine run on 94-octane unleaded gasoline. The fuel used is basically 100LL avgas minus the tetraethyl lead, according to TCM. “No knock or other detrimental operation [was] encountered,” said the company. TCM has been researching alternative piston-engine fuels since early 2007. Efforts include working with the Coordinated Research Council, analyzing various fuel options such as biofuel and autogas and conducting engine tests in TCM’s dynamometer-equipped test cells. The gasoline used in the flight tests–94 unleaded avgas–is the “most likely to be submitted for certification and standardization as a piston aviation fuel,” according to TCM. Advantages of 94UL are that it retains 100LL’s vapor-suppression and vapor-lock characteristics, is already compatible with existing airframe/engine systems, is stable for long-term storage and the refining and transportation infrastructure for 94UL is already in place.