The GAfuels Blog is written by two private pilots concerned about the future availability of fuels for piston-engine aircraft: Dean Billing, Sisters, Ore., an expert on autogas and ethanol, and Kent Misegades, Cary, N.C., an aerospace engineer and aviation journalist.
One unleaded aviation fuel that gets little press coverage is UL 91, approved by ASTM in June 2008 at the request of the U.S. Department of Defense as a fuel for UAVs. Since then, the military has shifted its focus to powerplants using “heavy” kerosene-based fuels such as diesel and JP-8. UL 91 is not currently in production. As an indication of the growing popularity of Swedish Hjelmco Oil’s 91/96 UL and 91/98 UL unleaded fuels, the ASTM is now considering the change of UL 91’s designation to NLA (Non-Leaded Avgas). It remains to be seen however, if any company produces it for military or civilian purposes.