A California congressman is urging the FAA to encourage wider availability of unleaded aviation fuel at airports to reduce the use of 100LL. In a (PDF) letter to Acting FAA Administrator Michael Huerta, Rep. Henry Waxman, D-Calif., says airplanes that can use unleaded fuel should use unleaded fuel until an unleaded replacement for avgas is available. He suggests the FAA become directly involved in helping airports ensure the availability of high-octane, ethanol-free unleaded gas. "It is essential for the FAA to develop and implement, in the near term, measures to facilitate the use of currently available unleaded fuel in general aviation," he wrote.
Waxman quotes a report by the Aviation Fuel Club, an organization created with the goal of lowering the cost of aviation fuel and fuel equipment, that says 80 percent of piston aircraft can be STC'd to run on unleaded ethanol-free fuel. What he doesn't mention is that by some estimates the 20 percent of aircraft that need 100-octane fuel burn 80 percent of the avgas. He also says the timeline for the 100-octane unleaded replacement fuel is too long.