This metric Aerospace Information Report (AIR) details a ball-on-cylinder (BOC) test device and specifies a method of rating the relative lubricity of aviation turbine fuel samples. The BOC produces a wear scar on a stationary steel ball by forcing it with a fixed load against a fuel wetted steel test ring in a control led atmosphere. The test ring is rotate data fixed speed so its surface is wetted by a momentary exposure to the fluid under test. The size of the wear scar is a measure of the test fluid lubricity and provides a basis for predicting friction or wear problems. Field of Application: To rate the lubricity of turbine fuels for the low lubricity pump endurance test or to determine fuel lubricity. NOTE: This document@ SAE ARP1797@ and AIR4027 are complementary documents on the subject of aircraft turbine fuel low lubricity. Background: In recent years an increasing amount of lower grade crude oil has been used in the production of aircraft turbine fuel. Hydrogen refining techniques remove the sulfur and polar constituents of the crude oil. Some high quality hydro-refined fuel products have very poor lubricating properties. These low lubricity fuels have caused friction and wear problems in aircraft components. The BOC tester will be increasingly essential to monitor fuel lubricity for fuel system component development tests@ production screening tests and field use.