Aircraft Engine Oils
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Questions and Answers

What primary function does the oil film serve between gears in an engine?

  • It increases friction.
  • It cushions contact. (correct)
  • It enhances thermal conductivity.
  • It provides electrical insulation.
  • How does oil contribute to engine cleaning?

  • It evaporates moisture.
  • It reacts chemically with contaminants.
  • It picks up foreign particles and suspends them. (correct)
  • It attracts carbon deposits.
  • What role does the oil film play in corrosion protection?

  • It serves as a barrier against moisture and oxygen. (correct)
  • It neutralizes acidic compounds.
  • It enhances surface roughness.
  • It strengthens metal components.
  • Why are synthetic lubricants preferred in gas turbine engines?

    <p>They retain characteristics at high temperatures.</p> Signup and view all the answers

    What is a potential consequence of using petroleum lubricants in high-temperature engine operations?

    <p>They form heavy hydrocarbons and deposits.</p> Signup and view all the answers

    What type of engine parts are especially prone to corrosion when exposed to moisture and chemicals?

    <p>Components hardened by nitriding.</p> Signup and view all the answers

    What does the oil do with foreign particles as it circulates through the engine?

    <p>It holds them in suspension.</p> Signup and view all the answers

    Which characteristic of synthetic oil contributes to reducing coking and lacquer formation in engines?

    <p>Resistance to evaporation.</p> Signup and view all the answers

    What is high film strength primarily required for?

    <p>To prevent oil from being forced out between moving parts</p> Signup and view all the answers

    How can high film strength be physically demonstrated?

    <p>By rubbing the oil rapidly between the fingers</p> Signup and view all the answers

    What does a high flash point indicate about the oil?

    <p>It must be heated to a high temperature to release vapors</p> Signup and view all the answers

    What is viscosity a measure of in lubricating oil?

    <p>The oil's resistance to flow</p> Signup and view all the answers

    Why is it important for oil to have both low viscosity and high film strength?

    <p>To ensure circulation while protecting moving parts</p> Signup and view all the answers

    Which statement about low viscosity oil is correct?

    <p>It flows freely and is generally less effective at high temperatures</p> Signup and view all the answers

    For synthetic oils used in gas turbine engines, what is the typical flash point?

    <p>Around 250 °C or above</p> Signup and view all the answers

    What is the primary challenge in achieving optimal oil performance?

    <p>Balancing high film strength with optimal viscosity</p> Signup and view all the answers

    What is one of the primary purposes of lubricating oil in aircraft engines?

    <p>To reduce friction between moving parts</p> Signup and view all the answers

    Which manual provides the correct oil specifications for a specific engine type?

    <p>Aircraft Maintenance Manual</p> Signup and view all the answers

    What could result from mixing oils with different specifications?

    <p>Damage to engine components</p> Signup and view all the answers

    How does lubrication oil assist in the cooling of engine bearings?

    <p>Through the absorption of heat from engine parts</p> Signup and view all the answers

    Why are liquid lubricants like oils predominantly used in aircraft engines?

    <p>They circulate freely to lubricate necessary parts</p> Signup and view all the answers

    What additional function does lubricating oil provide apart from reducing friction?

    <p>It protects against corrosion</p> Signup and view all the answers

    What happens to engine parts when they rub against one another without lubrication?

    <p>They undergo rapid wear</p> Signup and view all the answers

    What is an important characteristic of engine parts that affects lubrication?

    <p>They typically have a rough microscopical texture</p> Signup and view all the answers

    What is a major advantage of high volatile fuels?

    <p>Enhanced combustion</p> Signup and view all the answers

    What does a high vapour pressure indicate?

    <p>Higher risk of fuel vaporisation</p> Signup and view all the answers

    What temperature is associated with a fuel's flash point?

    <p>The temperature at which ignitable vapours are produced</p> Signup and view all the answers

    What is the primary purpose of the NACA scoop under the wings of an aircraft?

    <p>To create a head of pressure on the fuel</p> Signup and view all the answers

    What can happen if the vapour pressure of fuel is too low?

    <p>Fuel will not vaporise properly, causing starting problems</p> Signup and view all the answers

    Which of the following is a disadvantage of high volatile fuels?

    <p>Potential for vapour locks</p> Signup and view all the answers

    What is the impact of fast climbs on fuel vapourisation?

    <p>Increased risk of fuel loss through vaporisation</p> Signup and view all the answers

    Why are modern fuels designed to be less volatile?

    <p>To minimize fire hazards</p> Signup and view all the answers

    What form of water in aviation turbine fuel cannot be detected visually?

    <p>Dissolved water</p> Signup and view all the answers

    Where does free water typically settle in the aircraft's fuel system?

    <p>Near the boost pump inlet</p> Signup and view all the answers

    Which method is NOT typically used to check for water contamination in aircraft fuel?

    <p>Fuel sample analysis under lab conditions</p> Signup and view all the answers

    What happens to free water in sufficient quantities in aviation fuel?

    <p>It can form ice</p> Signup and view all the answers

    What color does the water finding paste turn when it detects water present?

    <p>Purple</p> Signup and view all the answers

    What type of water is referred to as being 'entrained' or 'suspended'?

    <p>Free water</p> Signup and view all the answers

    How often are aircraft fuel tanks checked before the first flight of the day?

    <p>Daily during routine checks</p> Signup and view all the answers

    Why is water contamination a concern for aviation turbine fuel?

    <p>It can form ice and hinder engine operations</p> Signup and view all the answers

    Study Notes

    Aircraft Engine Oils

    • Oil types have varying properties and characteristics; correct specification is crucial to prevent engine failure.
    • Oil specifications can be found in the Aircraft Operator’s Manual, Maintenance Manual, Engine Maintenance Manual, and oil tank service placard.
    • Mixing oils of different specifications or brands is prohibited.

    Lubrication

    • The primary role of lubricants is to reduce friction between moving parts and cool engine bearings.
    • Lubricants also cushion components, seal gaps, clean engine interiors, and protect against corrosion.
    • Liquid lubricants, particularly oil, are most commonly used due to their ability to circulate freely.
    • Engine parts have rough surfaces microscopically, which can cause wear; oil films reduce this friction.

    Cleaning

    • Lubricating oil serves as a cleaning agent, picking up particles like dirt, carbon, and water.
    • These particles are held in suspension and transferred to a filter for removal, helping to reduce engine wear.

    Corrosion Protection

    • Engine parts exposed to moisture and chemicals are at risk of corrosion, particularly hardened parts.
    • Oil creates a barrier that prevents oxygen and moisture contact with metal surfaces, mitigating rust and corrosion.

    Synthetic Oil Characteristics

    • High operational temperatures necessitate synthetics that can withstand conditions that cause petroleum oils to evaporate.
    • Synthetic oils resist breakdown, coking, and lacquer formation, making them ideal for turbine engines.
    • High film strength in oil is crucial to maintain a protective layer between moving parts, observable by a slick feel when rubbed.

    Flash Point

    • Flash point is the temperature at which oil emits flammable vapors; higher flash points reduce fire risks.
    • Synthetic oils for gas turbine engines typically have flash points above 250 °C.

    Viscosity

    • Viscosity indicates oil's flow resistance; it must be light enough for circulation but thick enough to form a lubricating film.
    • Low viscosity oils flow freely, while high viscosity oils flow slowly.

    Fuel Volatility

    • High volatile fuels enhance combustion and starting but pose fire hazards and vapor lock risks.
    • Key factors include flash point and vapour pressure, which influence ignition and vaporization risks.

    Vapour Pressure

    • Vapour pressure prevents fuel from vaporizing; NACA scoops create pressure in fuel tanks to aid in this.
    • Low vapour pressure can lead to starting issues as fuel may not vaporize effectively.

    Water Contamination of Fuel

    • Aviation fuel is hygroscopic, meaning water is always present from condensation.
    • Water exists in dissolved form (invisible) and free form (suspended), with free water posing operational threats like ice formation.
    • Regular checks for free water are necessary using fuel drain valves, detection caps, or water finding paste.

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    Lubricants and Fuels PDF

    Description

    This quiz covers the properties and characteristics of lubricating oils specifically for aircraft engines. Understand the importance of using the correct oil specifications and learn about various oil types, their applications, and grading methods. Test your knowledge on how these oils impact engine performance and reliability.

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