Which of the following is NOT one of the three basic functions of oil in a jet engine?

• A. Fuel supply
• B. Lubrication
• C. Cooling
• D. Cleaning

Answer: (A)

Oil in a jet engine has three main duties: lubrication, cooling, and cleaning. Lubrication forms a protective film between moving parts to minimize friction and wear, keeping gears and bearings from scuffing or seizing. Cooling works by carrying heat away from hot bearings and components through the oil to an oil cooler, helping prevent overheating. Cleaning involves detergents and dispersants in the oil that keep contaminants suspended and prevent varnish or sludge buildup, helping the engine stay clean internally.

Fuel supply, on the other hand, is not a function of the engine oil. Fuel is delivered by the fuel system directly to the combustor. That’s why the option describing fuel supply is not one of the oil’s basic roles.