<br/>The oxidation and copper corrosion stability of an aviation gasoline for piston aircraft is a more important research area than for ground-based motor gasolines because (1) on average there are only about 50 flight hours per year per piston aircraft, so avgas must hold up for a much longer storage time than ground-based motor gasolines and (2) for a 100LL fuel the precipitation of lead particles from tetraethyl lead (TEL) decomposition during fuel storage periods can catalyze fuel oxidation and further reduce the fuel’s motor octane rating, leading to safety concerns for general aviation.<br/>This research reports the oxidation and copper corrosion stability of 100LL avgas as well as that of an unleaded, high aromatic aviation fuel blend. The fuel oxidation kinetics were carried out based on the ASTM D873. Oxidation intermediates and products were characterized using FT-IR and comprehensive Two-Dimensional Gas Chromatography/Time of Flight Mass Spectrometry and Flame Ionized Detector (GCxGC/TOFMS, GCxGC/FID) for detailed hydrocarbon analyses and explanation of fuel oxidiation mechanisms and procedures. Analyses of each fuel’s physical and chemical properties before and after fuel oxidation, such as fuel net heat of combustion, viscosity and vapor pressure, were also carried out based on related ASTM standards to investigate the effects of fuel oxidation. Results of copper strip corrosion tests have proven that tetraethyl lead in 100LL avgas can be oxidized and precipitated onto a copper strip surface. Scan Electron Microscopy and Energy Dispersion Spectroscopy tests were carried out to analyze the morphology of lead and carbon particles on the surface of copper strip for obtaining a deeper understanding of fuel corrosion processes and mechanisms. In comparison with an unleaded high aromatic fuel blend, 100LL fuel has a greater tendency to induce copper corrosion due to the TEL decomposition. Detailed hydrocarbon analyses by comprehensive GCxGC/TOFMS analyses further proved this finding via the detection of TEL additive and the formation of other oxygenated hydrocarbons.<br/>

Oxidation stability of unleaded alternative aviation gasolines

2019 Spring National Meeting

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