Engine Lubrication Systems Quiz

Engine Lubrication Systems

• Lubrication system's primary role is supplying oil to engine parts to combat friction and heat.
• Engine heat is managed through the nacelle ventilation system and internal lubrication.
• Oil is pressurized and circulated to reduce friction, cool components, and maintain cleanliness.
• Capitalizes on a scavenging system that returns oil to storage for reuse.
• Gas turbine engines have lower oil consumption compared to piston engines, resulting in smaller bulk oil storage requirements (3-5 L for business jets, 20-30 L for commercial engines).
• Oil remains relatively clean due to minimal exposure to combustion products and efficient filtration.
• Oil temperature is monitored and controlled through automatic cooling devices to prevent rapid decomposition.

Lubrication System Types

• Two self-contained lubrication systems utilized in gas turbine engines: Pressure relief valve system and Full flow system.
• Pressure relief valve system limits oil pump pressure; full flow system allows pressure variance with RPM.

Lubrication System Classifications

• Lubrication systems categorized as Wet-sump or Dry-sump.
• Wet-sump: Oil stored directly in the engine.
• Dry-sump: Oil stored in an external reservoir; scavenge pumps collect accumulated oil for recirculation.

Oil Reservoir

• Essential for holding sufficient oil for maximum operation duration.
• Reservoirs are often pressurized to ensure positive oil flow and suppress foaming, preventing pump cavitation.
• Pressurization is achieved using an adjustable relief valve in the vent line.

Expansion Space

• Oil reservoirs feature a minimum 10% expansion space or 0.5 gallons for oil expansion and foam collection.
• Oil filler caps marked with "OIL" and permissible oil designations for proper identification.
• Many dry-sump system reservoirs include scupper drains to catch spills and overflows during servicing.

Bypass Valves

• Bypass valves are critical for preventing oil starvation if a component becomes blocked.
• Operates similarly to pressure relief valves, allowing oil to bypass when pressure increases due to blockage.
• Incorporated in all filters and oil coolers with indicators to signal when a blockage occurs.

Oil Filters

• Oil filters are crucial for removing contaminants from lubrication systems.
• Common types include Laminated paper, Cleanable screen, Screen and spacer, and Thread filters.

Thread Filters

• Act as ‘last chance’ filters, positioned before the oil jets that lubricate bearings.
• Designed with a threaded inner element for effective oil filtration prior to entering bearings.

Oil Filter Bypass

• All oil filters must allow full oil flow even if blocked, achieved through an integrated oil bypass valve.
• Warning systems, including cockpit lights and visual indicators, alert operators to bypass situations.

Vents

• Vents, or breathers, are integral for preventing excess air pressure within oil tanks and bearing chambers.
• Essential for ensuring proper oil gravity feeding and effective scavenging.
• Commonly employs a centrifugal breather design, using centrifugal force to separate oil from air and return it to the sump while venting clean air.
• Most systems maintain a 5–7 psi pressure head using a vent-pressurizing valve with a spring-loaded pressure relief valve.

Test your knowledge on the functioning of engine lubrication systems. This quiz covers the role of lubrication in managing heat, reducing friction, and maintaining cleanliness in engine components. Explore the differences between gas turbine and piston engines, including oil consumption and scavenging systems.