4.8 Unleaded Fuels Program

As a result of the mandates of the 1990 Clear Air Act, the FAA initiated unleaded fuel research and engine and fuel testing. Such testing is being conducted in cooperation with an FAA and industry-established Coordinating Research Council (CRC) Committee, to address issues such as engine detonation, material compatibility, volatility (vapor lock), engine performance, storage stability, water reaction, emissions, fuel consumption changes, and durability (engine and component life).

Engine and fuel tests are currently being conducted to validate the octane requirement that is acceptable for engines within the existing general aviation fleet. At the conclusion of these tests, minimum octane requirements for candidate unleaded fuel formulations will be specified as a development goal for participating oil companies within the CRC Committee. The FAA will then evaluate these fuels through a series of performance- and safety-related engine fuel tests.

Data from these tests will aid the FAA in certifying the existing fleet of general aviation aircraft on a replacement fuel, and in developing a specification with the American Society of Testing and Materials (ASTM) for an unleaded aviation gasoline to replace the currently available 100-octane low-lead fuel. This specification, in turn, will serve as a basis for the development of advisory material covering the certification of new piston-powered engine designs and their application to the performance of new general aviation airplanes. Further testing at the FAA's small-engine test facilities is anticipated, to define the safety and performance of other critical in-service aircraft engines that have not been tested with the newer unleaded fuels, as well as to develop other new or alternative fuels.

FAA POC:
Stewart Byrnes
609-485-4499
stewart.byrnes@faa.gov