LUBRICITY PROPERTIES OF HIGH-TEMPERATURE JET FUELS

Abstract
A field survey of engine and pump manufacturers indicated that there is a potential problem whenever jet fuels are the only source of lubrication in pumps or controls. Problems encountered included wear, scuffing, sticking, seizure, and fatigue pitting. A literature survey confirmed that the problem existed but failed to pinpoint the causes. The friction and wear performance of ten commercial fuels, chosen to represent a broad range of physical and chemical properties, differed markedly. These fuels were inspected for viscosity, volatility, hydrocarbon type, and trace constituents. The strongest factor affecting lubricity appeared to be the nature of trace polar components in the fuel. The exact components responsible have not yet been determined. The occurrence of sticking in the fuel control valve of operational jet engines led to the examination of a number of commercial JP-4's from different sources. There was a good correlation between field performance of the fuels and their performance in the laboratory tests. It was found that as little as 15 ppm of corrosion inhibitors significantly improved the lubricity in laboratory tests of these fuels that lacked lubricating properties of their own. Other lubricity additives were even more effective.

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