In mid-January, the EPA released a letter addressed to several environmental groups and one county in California stating that the agency now intends to develop a proposal regarding whether lead emissions from piston-engine aircraft cause or contribute to air pollution that may reasonably be anticipated to endanger public health or welfare. The EPA plans to issue a proposed endangerment finding later this year. After evaluating comments on the proposal, the EPA plans to issue any final endangerment finding in 2023. To read these letters, click here.
Although the automotive industry has been able to move away from leaded fuel by using fuels such as ethanol, the same fuel transition cannot be as easily accomplished with aircraft. Adding ethanol to avgas could lead to vapor lock, cause corrosion, possibly introduce water into the fuel system and reduce the energy content of the fuel. The EPA has in the past accepted the case for continuing to use lead in aviation fuel as it is necessary for the safety of flight with gasoline-powered engines. NAAA insists on safety first for aircraft operations that depend on leaded aviation fuels and will comment as such to the EPA.
An endangerment finding could result in the elimination of leaded avgas. There has been concern about lead in aviation fuel since the 1980s when lead was removed from automotive fuel. While no good solution has been previously found, a new unleaded fuel has been developed. NAAA reported in the July 29, 2021 eNewsletter that the Federal Aviation Administration formally awarded a supplemental type certificate (STC) to General Aviation Modifications Inc. (GAMI) for an unleaded 100-octane avgas called G100. The list of approved engines has been greatly expanded, with more engine approvals expected in the spring of 2022.