2.20. SUMMARY

Gas turbine engine oil systems perform three major functions. They clean and reduce friction, and they cool and dissipate heat. They also clean the engine interior through the use of oil filters and strainers. Because much of the aircraft powerplant consists of moving parts, lubricants are needed to overcome friction caused by one metal surface sliding or rolling over another. Friction causes heating of parts, excessive wearing, and useless expenditure of horsepower. Lubricating systems used in gas turbine engines have oil tanks, pressure pumps, scavenger pumps, filter, oil coolers, and spray oil jets. The system most widely used on turbine engines is the dry sump lubrication system which uses a separate or external oil tank, located near the engine.

The two kinds of pumps are pressure pumps and scavenge pumps, the first to put oil into the system, and the second to collect oil from the system. Filters remove foreign matter from the oil, and either a fuel oil-cooler or an air cooler takes the heat out of it. Oil is sprayed on the bearing surface by spray jets.

Section III. Ignition Systems and Engine Instrumentation

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