This report describes the results of a study that measured the effects of pressure altitude on fuel weathering. In this study, samples of unleaded automobile gasoline were exposed to varying pressure altitudes, and the effects of this exposure on aircraft performance and volatility were measured. The composition of the fuel, aircraft configuration, and the initial temperature of the fuel when transferred to the tank were varied to determine the extent these variables affect aircraft performance.

The experiments that were conducted demonstrated that the use of 43°C (110°F) automobile gasoline for aircraft certification procedures is a severe test that ensures the greatest margin of safety. In addition, it was shown that methyl-tertiary-butyl ether is an acceptable fuel for use in general aviation aircraft.

Several different oxygenated fuels (including gasolines containing alcohols) were weathered in ground-based tests, and the results are presented here.