Small airplanes are finally switching to unleaded fuel

Cessnas, Pipers and other small airplanes — now the largest U.S. lead emitters — are on the verge of a historic shift to unleaded fuel.

Why it matters: Lead exposure has been linked to a host of health and developmental issues.

• Historic exposure to lead, mostly from car exhaust, lowered the IQ of about half the U.S. population, per one recent study.

Compared to cars, small airplanes account for a fraction of total emissions. Yet lead's health risks are frequently cited by people seeking to close local airports, which often serve as training grounds for would-be professional pilots — and there's a shortage of those.

• U.S. regulators banned the use of leaded gasoline in passenger cars in 1996, but aircraft were exempt because there was no "operationally safe, suitable replacement," per the Federal Aviation Administration (FAA).

What's happening: The FAA recently approved just such a replacement, developed by General Aviation Modifications, Inc. (GAMI), for use across the general aviation fleet — without any major, potentially cost-prohibitive aircraft or engine modifications.

• GAMI is scaling up production of the fuel, called G100UL, by licensing production and distribution.
• G100UL may first show up at airports in California, where at least one county has banned leaded aviation fuel despite a lack of existing universal alternatives.
• Another company, Swift Fuels, is also developing unleaded aviation fuels.

What they're saying: The FAA will require GAMI to "work with aircraft owners to track and report any unforeseen mechanical issues that might arise from introducing its fuel into existing fuel systems," deputy administrator Bradley Mims said in a statement.

History lesson: Tetraethyl lead was first added to gasoline in the 1920s to prevent "engine knock," which can reduce performance and cause damage.

The intrigue: Some in the general aviation world feared that the Environmental Protection Agency would some day move to ban leaded aviation fuel regardless of whether an alternative was available.

• That put pressure on manufacturers to come up with an unleaded option.
• Manufacturers, meanwhile, are becoming less willing to work with leaded fuels, given the health risks involved.

Of note: None of this affects big commercial airliners, which typically use unleaded, kerosene-based jet fuel.

• Health benefits aside, unleaded fuel is also better for airplane engines — lead can cause spark plug fouling, which curbs engine performance and can be a safety hazard if not promptly addressed.

💬 Alex's thought bubble: Almost every small plane pilot I've spoken to about this is excited for the change — none of us want to be spewing lead.

Yes, but: Gas is still gas, and viable electric aircraft largely remain a distant dream.

What's next: Pilots are being told to expect G100UL to start appearing for sale in the coming months, if all goes well with manufacturing and distribution.