Systems Lubrication EXAM QUESTIONS ACCURATE AND VERIFIED ACTUAL EXAM QUESTIONS WITH DETAILED ANSWERS FOR GUARANTEED PASS | ALREADY GRADED A

In which of the following situations will the oil cooler automatic bypass valve be open the greatest amount? A. Engine oil at high operating temperature B. Engine off C. Engine oil below normal operating temperature D. Oil cooler malfunction Correct Answer: C. Rationale: The bypass valve opens most when oil is cold to allow it to bypass the cooler and reach operating temperature more quickly. The purpose of a dwell chamber in a turbine engine oil tank is to provide... A. Storage for excess oil B. Cooling for hot oil C. Separation of entrained air from scavenged oil D. A pressure buffer for oil supply Correct Answer: C. Rationale: The dwell chamber allows entrained air to separate from the returning oil before it is recirculated. As a general rule, the mixture setting on a reciprocating engine operating at or near takeoff power that provides the best cooling is... A. Full lean B. Best economy C. Full rich D. Lean of peak Correct Answer: C. Rationale: A full rich mixture provides more fuel, which cools the engine by absorbing heat during vaporization. What is the primary purpose of the oil breather pressurization system that is used on turbine engines? A. Prevent oil leakage B. Remove air from oil C. Provides a proper oil spray pattern from the main bearing oil jets D. Assist in combustion Correct Answer: C. Rationale: The pressurization system ensures a consistent oil spray pattern necessary for bearing lubrication. Some larger reciprocating engines use a compensating oil pressure relief valve to... A. Increase pressure during start-up only B. Maintain constant pressure C. Provide a high engine oil pressure when the oil is cold and automatically lower the oil pressure when the oil warms up D. Prevent air entrainment Correct Answer: C. Rationale: This valve adjusts oil pressure depending on oil temperature, preventing overpressure when oil is cold. The purpose of the flow control valve in a reciprocating engine oil system is to... A. Maintain constant flow B. Regulate oil temperature C. Direct oil through or around the oil cooler D. Separate air from oil Correct Answer: C. Rationale: It ensures oil is either routed through the cooler or bypassed depending on temperature needs. What is the primary purpose of the oil-to-fuel heat exchanger? A. Heat the fuel for better combustion B. Cool the oil C. Separate contaminants D. Increase fuel pressure Correct Answer: B. Rationale: The primary function is to cool the oil by transferring heat to the fuel. The time in seconds required for exactly 60 cubic centimeters of oil to flow through an accurately calibrated orifice at a specific temperature is recorded as a measurement of the oil's... A. Flash point B. Weight C. Viscosity D. Purity Correct Answer: C. Rationale: Viscosity is measured by flow rate at a specific temperature through a standard orifice. Which of the following lubrication system components is never located between the pressure pump and the engine pressure system? A. Oil temperature bulb B. Fuel line for oil dilution system C. Check valve D. Oil filter Correct Answer: B. Rationale: The oil dilution system is not part of the pressurized oil delivery path to the engine. In order to relieve excessive pump pressure in an engine's internal oil system, most engines are equipped with a... A. By-pass screen B. Surge valve C. Oil flow meter D. Relief valve Correct Answer: D. Rationale: A relief valve protects the system from overpressure by venting excess oil. Compared to reciprocating engine oils, the types of oils used in turbine engines... A. Have higher detergent content B. Have less tendency to produce lacquer or coke C. Are based on vegetable oil D. Are more viscous Correct Answer: B. Rationale: Turbine oils are designed to resist coking and lacquer formation under high temperatures. Which of the following is a function of the fuel-oil heat exchanger on a turbojet engine? A. Aerates the fuel B. Emulsifies the oil C. Increases fuel temperature D. Decreases fuel density Correct Answer: C. Rationale: It transfers heat from oil to fuel, raising fuel temperature for better atomization. Which of the following factors helps determine the proper grade of oil to use in a particular engine? A. Adequate lubrication in various attitudes of flight B. Positive introduction of oil to the bearings C. Operating speeds of bearings D. Oil type label Correct Answer: C. Rationale: Bearing speeds affect oil viscosity and grade selection. How are the teeth of the gears in the accessory section of an engine normally lubricated? A. By gravity B. By grease C. By splashed or sprayed oil D. By hand Correct Answer: C. Rationale: Gears are typically lubricated using splash or spray oil systems. Upon what quality or characteristic of a lubricating oil is its viscosity index based? A. Resistance to oxidation B. Rate of change in viscosity with temperature change C. Water content D. Flash point Correct Answer: B. Rationale: Viscosity index indicates how much the oil's viscosity changes with temperature. The recommended aircraft engine lubricants are... A. Petroleum only B. Vegetable based C. Mineral or synthetic based D. Water-based emulsions Correct Answer: C. Rationale: Aviation engines use either mineral or synthetic oils for lubrication. From the following, identify the factor that has the least effect on the oil consumption of a specific engine. A. Mechanical efficiency B. Engine RPM C. Lubricant characteristics D. Ring seal condition Correct Answer: A. Rationale: Mechanical efficiency has little to no direct influence on oil consumption. What is the purpose of the last chance oil filters? A. Filter oil before draining B. Filter fuel C. Filter the oil immediately before it enters the main bearings D. Clean air from oil Correct Answer: C. Rationale: These filters protect critical components like bearings from last-minute contaminants. Where is the oil temperature bulb located on a dry sump reciprocating engine? A. In the oil tank B. In the scavenge line C. In the oil inlet line D. On the oil pressure gauge Correct Answer: C. Rationale: The bulb is placed in the oil inlet line to measure the temperature of oil entering the engine. High tooth pressures and high rubbing velocities, such as occur with spur-type gears, require the use of... A. Graphite-based oils B. Detergent oils C. An EP lubricant D. Low viscosity oil Correct Answer: C. Rationale: EP (extreme pressure) lubricants are designed for heavy-load, high-friction gear applications. What would be the probable result if the oil system pressure relief valve should stick in the open position on a turbine engine? A. Overheating B. Insufficient lubrication C. High oil temperature D. Excessive oil pressure Correct Answer: B. Rationale: An open relief valve can cause a drop in oil pressure, resulting in poor lubrication. Why is an aircraft reciprocating engine oil tank on a dry sump lubrication system equipped with a vent line? A. For checking pressure B. To refill oil C. To prevent pressure buildup in the oil tank D. To drain excess oil Correct Answer: C. Rationale: The vent prevents pressure buildup and allows for proper oil flow and scavenging. Which of these characteristics is desirable in turbine engine oil? A. Low flash point B. High flash point C. High volatility D. High pour point Correct Answer: B. Rationale: A high flash point ensures the oil does not ignite under normal engine operating temperatures. The type of oil pumps most commonly used on turbine engines are classified as... A. Gearless B. Centrifugal C. Positive displacement D. Diaphragm Correct Answer: C. Rationale: Positive displacement pumps deliver a constant volume of oil, ensuring reliable pressure. What is the source of most of the heat that is absorbed by the lubricating oil in a reciprocating engine? A. Exhaust gases B. Bearings C. Pistons and cylinder walls D. Oil pump Correct Answer: C. Rationale: These components generate significant heat during combustion and friction. What will happen to the return oil if the oil line between the scavenger pump and the oil cooler separates? A. Oil will recirculate through the tank B. Oil will back up in the system C. The return oil will be pumped overboard D. Oil pressure will increase Correct Answer: C. Rationale: A broken line can cause oil to be lost overboard, risking engine lubrication failure