General Principles
What is the primary purpose of an engine lubrication system?
To reduce friction, remove heat, prevent corrosion, clean contaminants, and seal components.
What is the purpose of the oil pump?
To circulate oil under pressure throughout the engine.
What is pressure lubrication?
Oil is forced under pressure to engine bearings and moving parts.
What types of oil are used in aircraft engines?
Mineral oil and ashless dispersant (AD) oil.
What happens to oil after it lubricates the engine?
It drains back to the sump or is scavenged.
What are the main functions of lubricating oil?
Lubrication, cooling, cleaning, sealing, and corrosion protection.
What type of oil pump is commonly used?
Gear-type and gerotor pumps.
What is splash lubrication?
Oil is splashed onto components by moving parts.
What is ashless dispersant oil?
Oil with additives that keep contaminants suspended.
What does a scavenger pump do?
Returns oil from the engine to the oil tank (dry sump).
What types of lubrication systems are used in aircraft engines?
Wet sump and dry sump systems.
What does the oil pressure relief valve do?
Maintains proper oil pressure by bypassing excess oil.
Where is oil pressure typically measured?
At the outlet of the oil pump or pressure line.
What does viscosity mean?
The oil’s resistance to flow.
Why are multiple scavenger pumps used?
To ensure complete oil removal from various engine sections.
What is a wet sump system?
Oil is stored in the engine crankcase.
What is the function of the oil cooler?
Removes excess heat from the oil.
Why is proper oil pressure important?
Ensures adequate lubrication and prevents engine damage.
Why is viscosity important?
It affects lubrication and flow at different temperatures.
What is oil foaming and why is it bad?
Air mixed with oil reduces lubrication effectiveness.
What is a dry sump system?
Oil is stored in an external tank and circulated through the engine.
What is an oil temperature regulator or bypass valve?
Controls oil flow through the cooler to maintain proper temperature.
What happens if oil pressure is too low?
Insufficient lubrication, leading to wear or failure.
What is viscosity index?
Indicates how viscosity changes with temperature.
How is oil aeration reduced?
Through proper tank design and deaeration features.