The Fight Over Avgas
Can private pilots fly unleaded?
- By David Freed
- Air & Space magazine, August 2013
Photo-illustration by Théo. Nozzles by Chad Slattery. Airfield © 2012 Marc Espolet / iStockphoto.
I’m hooked on lead. Maybe not in the way a junkie is addicted to drugs, but hooked nonetheless. The tetraethyl lead added to aviation fuel helps keep the engine of my four-seat, 48-year-old Piper Cherokee running smoothly. And that keeps me happy.
Thousands of pilots who fly piston-powered airplanes are kept happy by the lead in their fuel tanks, but outside of the world of aviation, few see lead as anything other than a health hazard. Environmentalists are demanding that lead be removed from aviation fuel, in much the way the Clean Air Act of 1970 phased it out of automobile gas. The Federal Aviation Administration is moving steadily in that direction. Agency officials have set as a goal making unleaded fuel available for most aircraft by 2018.
But here’s the hitch: After some 20 years of research and development, no one has come up with a completely proven and affordable lead-free fuel for piston engines that will satisfy the needs of the entire general aviation fleet.
Experts estimate that of the nation’s 200,000 piston aircraft, as many as 70 percent could, in theory, use the same unleaded “mogas,” or autogas, that cars and trucks run on—with little or no re-engineering. But autogas in its present form, they warn, is hardly an elixir. Its formulation varies from state to state as petroleum producers and air quality specialists tinker with such things as vapor pressures, which can affect the delicately balanced performance of an aircraft engine. Autogas also contains increasing amounts of corn-derived ethanol, which can trap water in aircraft fuel lines; at high altitude, the water freezes.
As for the other 30 percent of the general aviation fleet—typically high-performance, piston-driven, commercial aircraft like air ambulances and short-haul regional carriers, which serve smaller, mostly rural markets—there is no alternative to the low-lead fuel known as “avgas” that their engines were designed to use. These airplanes cannot fly safely, if at all, without leaded avgas in their tanks.
For advocates of general aviation, the quandary has become nothing short of existential. “This is not a crisis, but it is an urgent issue,” says Doug Macnair, vice president of government relations for the 176,000-member Experimental Aircraft Association. “Our community lives or dies by this issue. Whatever the outcome, it’s going to be the most sweeping change we have ever seen in this industry.”
That kind of pronouncement hardly engenders confidence among owners like me: fliers of older, low-end aircraft who have watched as each year the avocation we love becomes more expensive. We live in dread of fuel costs continuing to rise and of FAA airworthiness directives, which often require us to pay for expensive, usually safety-related modifications. Will a government-mandated switch to unleaded fuel ultimately break the bank, leaving us little recourse but to quit flying and sell our airplanes with their environmentally unfriendly engines—if anybody wants them?
To find out, I decided to first consult my own aviation guru—certified airframe- and-powerplant mechanic Dan Torrey, who works alongside his son Brian out of a modest aluminum hangar in Santa Paula, California, and to whom I have entrusted the maintenance of my airplane for years.