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CONTINUOUS increase in the power output of aircraft engines introduces from time to time lubricating problems including excessive wear and scuffing, excessive oxidation of the oil, and ring sticking. The one problem of ring sticking was chosen and the discussion is limited to the testing of lubricating oils to compare their abilities to prevent this type of failure. Although the best answer as to the ring-sticking tendencies of a lubricant rests with the full-scale engine in service, a simple test is needed during the development period. The development work which led up to the selection of an L-head CFR engine for a ring-sticking test is discussed. Various criteria used for detecting incipient ring sticking are mentioned and a method for direct measurement of incipient ring sticking is described.

A study has been made by the Coordinating Research Council (CRC) of electrostatic phenomena during the fueling of both a full-scale mockup of a typical jet aircraft wing tank and a small-scale rig representing a single compartment of an integral wing tank. The tests were performed with equipment typical of modern aircraft fueling installations and using several batches of typical aviation turbine fuels as supplied by the manufacturers.

Engine lubricating oils have responded to the increasingly severe requirements introduced by engine design improvements for more than thirty years. It is expected that design trends in the future will be continuations of the past and current ones for the most part. This means that lubricants for future piston engines must have improved dispersancy, thermal and oxidative stability, as well as improve boundary lubrication capability. The latter is especially important and will require serious effort on the part of the engine designer and metallurgist, in company with the lubricant designer. Mineral oils will be improved and, with improved additive combinations, will continue to serve engine needs far into the future. Synthetic materials will not challenge them seriously for at least the next decade, principally for economic reasons. However, synthetics will be required, as they are now, for industrialized aircraft gas turbines.

SEVEN HUNDRED tons of iron, estimated by the authors to be worn annually from the cylinder bores of American automotive engines, cause an annual engine repair bill believed to exceed $1,000,000,000. A large part of this wear is due to corrosion, particularly in severe service such as gasoline-powered delivery vehicles or stationary diesel installations. Test results indicate that wear rates can be materially reduced by the use of crankcase lubricating oils containing high concentrations of alkalinity. The authors also present examples of radiochemistry research. Radiotracers are used to prove that oil consumed by the engine carries with it the iron debris which it contained at the moment of consumption.