Engine Lubrication Systems Quiz
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Questions and Answers

What is the primary purpose of pressurising the oil reservoir in a dry-sump oil system?

  • To allow for easier oil drainage
  • To prevent oil foaming and pump cavitation (correct)
  • To facilitate oil storage during servicing
  • To increase the viscosity of the oil
  • What minimum expansion space is required in an oil reservoir?

  • 5% of tank capacity
  • 1 gal or 10% of tank capacity, whichever is lesser
  • 10% of tank capacity or 0.5 gal, whichever is greater (correct)
  • 15% of tank capacity
  • What is the primary function of the engine lubrication system?

  • To filter oil before it enters the engine
  • To regulate air pressure in the engine compartments
  • To supply oil to reduce friction and cool engine components (correct)
  • To store fuel for engine operation
  • What function do scavenge pumps serve in a dry-sump oil system?

    <p>They collect oil and pump it back to the reservoir</p> Signup and view all the answers

    How does the lubrication system help deal with heat radiating into the engine?

    <p>By supplying oil and cooling through scavenging</p> Signup and view all the answers

    What is a notable characteristic of oil consumption in gas turbine engines compared to piston engines?

    <p>Gas turbine engines have lower oil consumption</p> Signup and view all the answers

    Where is the adjustable relief valve typically installed in a dry-sump oil system?

    <p>In the oil reservoir vent line</p> Signup and view all the answers

    What is the purpose of marking oil filler caps with the word 'OIL'?

    <p>To indicate the oil type needed</p> Signup and view all the answers

    What is the function of the pressure relief valve system in an engine lubrication system?

    <p>To control oil flow by limiting pressure from the oil pump</p> Signup and view all the answers

    What type of lubrication system is preferred when bearing vent cavities are under high air pressure?

    <p>Full flow system</p> Signup and view all the answers

    How does the expansion space in the oil reservoir affect oil management?

    <p>It provides space for oil expansion and foam collection.</p> Signup and view all the answers

    What is the purpose of the oil reservoir in an engine lubrication system?

    <p>To hold sufficient oil for maximum flight operation</p> Signup and view all the answers

    What risk is mitigated by the combination of pressure regulation and expansion space in the oil reservoir?

    <p>Oil foaming and pump cavitation</p> Signup and view all the answers

    What is a scupper drain used for in an oil reservoir?

    <p>To collect spillage during servicing</p> Signup and view all the answers

    How is oil returned to the storage tank in a lubrication system?

    <p>Using a scavenging system</p> Signup and view all the answers

    Why is careful temperature control essential in engine lubrication systems?

    <p>To avoid rapid oil decomposition</p> Signup and view all the answers

    What is the primary function of a bypass valve in an oil system?

    <p>To prevent the engine from being starved of oil due to a blockage.</p> Signup and view all the answers

    Which type of filter is NOT mentioned as a common type found in oil systems?

    <p>Centrifugal filter</p> Signup and view all the answers

    What happens when a blockage occurs in the oil system?

    <p>The bypass valve opens to allow oil to bypass the blocked component.</p> Signup and view all the answers

    What signals may indicate that a component is blocked in the oil system?

    <p>A pop-up indicator on the oil filter or a cockpit light.</p> Signup and view all the answers

    What is a characteristic of laminated paper filters used in oil systems?

    <p>They consist of a pleated paper element around a steel core.</p> Signup and view all the answers

    What type of valves are usually incorporated within an oil cooler?

    <p>Bypass and thermostatic valves.</p> Signup and view all the answers

    Why are oil filters essential in lubrication systems?

    <p>To remove harmful contaminants from the oil.</p> Signup and view all the answers

    In the event of a blockage in an oil filter, how does the system respond?

    <p>The system senses the increase in pressure and the bypass valve opens.</p> Signup and view all the answers

    What is the primary function of thread filters in gas turbine engines?

    <p>To filter oil just before it reaches the jet for the bearing</p> Signup and view all the answers

    Which statement accurately describes the construction of a thread filter?

    <p>It includes an inner threaded element housed within an unthreaded outer casing.</p> Signup and view all the answers

    What role does the bypass valve in oil filters play?

    <p>It allows for full oil flow even if the filter becomes completely blocked.</p> Signup and view all the answers

    Why is it important for turbine-powered aircraft to have a warning light for the oil filter?

    <p>To notify the operator when the filter is being bypassed.</p> Signup and view all the answers

    What can be inferred about the filtration capability of a thread filter with finer-pitched threads?

    <p>It offers greater filtration efficiency than coarser threads.</p> Signup and view all the answers

    What happens when an oil filter becomes completely blocked?

    <p>The bypass valve allows oil to flow unfiltered.</p> Signup and view all the answers

    What type of indicator is often added to filter housing as a visual bypass warning?

    <p>A red 'pop-out' clogging indicator.</p> Signup and view all the answers

    In terms of oil filtration, what is the consequence of using unfiltered oil for lubricating main bearings?

    <p>It can cause extensive damage to the engine.</p> Signup and view all the answers

    What is the primary purpose of vents or breathers in oil tanks and bearing chambers?

    <p>To prevent excess air pressure build-up</p> Signup and view all the answers

    What role does air pressure play in oil tanks and bearing chambers?

    <p>It assists gravity feeding of the oil</p> Signup and view all the answers

    Which type of breather is most commonly used in oil vent systems?

    <p>Centrifugal breather</p> Signup and view all the answers

    What is the function of a centrifugal breather in the oil vent system?

    <p>It uses centrifugal force to separate oil from air</p> Signup and view all the answers

    What is the typical pressure maintained by the vent pressurising valve within oil tanks and bearing chambers?

    <p>5-7 psi</p> Signup and view all the answers

    What components are involved in the vent-pressurising valve?

    <p>An aneroid bellows and a pressure relief valve</p> Signup and view all the answers

    What happens to the clean vent air in a typical oil vent system?

    <p>It is routed overboard</p> Signup and view all the answers

    Why is a certain amount of air pressure necessary in the bearing chambers?

    <p>To allow proper scavenge and oil jet spray</p> Signup and view all the answers

    Study Notes

    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.

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    Engine Lubrication Systems PDF

    Description

    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.

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