Aircraft Fuels and Lubricants
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Questions and Answers

What is the main characteristic of a lubricating oil's viscosity?

  • Its rate of flow through an orifice at a standard temperature
  • Its rate of change in viscosity with temperature change (correct)
  • Its resistance to flow at a standard temperature
  • Its specific gravity

    • Compared to reciprocating engine oils, which characteristic is more prominent in turbine engine oils?

  • Higher flash point
  • Less tendency to produce lacquer or coke (correct)
  • Higher viscosity index
  • Greater demulsibility

    • What is the primary function of engine oil, apart from lubricating?

  • Cooling and sealing
  • Cooling, sealing, preventing corrosion, and cushioning shock loads (correct)
  • Cushioning shock loads and preventing corrosion
  • Preventing corrosion only

    • What determines the proper grade of oil to use in a particular engine?

    <p>Operating speeds of bearings</p> Signup and view all the answers

    What is specific gravity a measure of?

    <p>Weight of a substance compared to an equal volume of distilled water</p> Signup and view all the answers

    What is an advantage of mineral base lubricants over vegetable oil base lubricants in aircraft engines?

    <p>Chemical stability</p> Signup and view all the answers

    What type of lubricant is required for high tooth pressures and high rubbing velocities, such as occur with spur type gears?

    <p>E.P lubricant</p> Signup and view all the answers

    What is a desirable characteristic of turbine engine oil?

    <p>High flash point</p> Signup and view all the answers

    What is done to protect integral fuel tanks from corrosion due to micro biological contamination?

    <p>A biocidal additive is added to the fuel</p> Signup and view all the answers

    What is the ideal oil for achieving theoretically perfect engine lubrication?

    <p>The thinnest oil that will stay in place and maintain a reasonable film strength</p> Signup and view all the answers

    What parameter needs to be adjusted when switching to an alternate fuel in a turbine engine?

    <p>Fuel specific gravity setting</p> Signup and view all the answers

    Why is kerosene used as a turbine engine fuel?

    <p>It has more heat energy per gallon and lubricates fuel system components</p> Signup and view all the answers

    What is calorific value a measure of?

    <p>The amount of heat or energy in one pound of fuel</p> Signup and view all the answers

    What type of oil is commonly used in gas turbine engines?

    <p>Synthetic oil</p> Signup and view all the answers

    What does an oil spectroscope measure?

    <p>Contaminants suspended in the oil</p> Signup and view all the answers

    What factors affect the ignition of fuel in a turbine engine?

    <p>Both volatility and atomisation</p> Signup and view all the answers

    Why is kerosene preferred over gasoline in turbine engines?

    <p>Kerosene is less volatile and has good lubrication properties</p> Signup and view all the answers

    What happens to the weight of a tank of fuel when its specific gravity is increased?

    <p>It increases</p> Signup and view all the answers

    What is the temperature at which the Reid vapour pressure of a fuel is measured?

    <p>38°C</p> Signup and view all the answers

    Which of the following is affected by the specific gravity of fuel?

    <p>Aircraft range</p> Signup and view all the answers

    At what air/fuel ratio will kerosene burn effectively?

    <p>15:1</p> Signup and view all the answers

    What should be done with Prist or Biopor during use?

    <p>It is left and burnt with the fuel.</p> Signup and view all the answers

    What does D.E.R.D 2494 refer to?

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

    What does a high viscosity index indicate about oil viscosity?

    <p>It will not vary greatly with temperature change.</p> Signup and view all the answers

    What is the function of a fuel system icing inhibitor?

    <p>It prevents the water in the fuel from freezing.</p> Signup and view all the answers

    What is the likely outcome of using a lubricant recommended for lower temperatures in extremely high-temperature conditions?

    <p>The oil pressure will be lower than normal.</p> Signup and view all the answers

    Which measurement indicates the flow characteristics of oil through an orifice?

    <p>The time required for a specific volume to flow.</p> Signup and view all the answers

    What happens to oil pressure when an engine is run in extremely high temperatures with an inappropriate lubricant?

    <p>The oil pressure will be lower than normal.</p> Signup and view all the answers

    Study Notes

    Lubricants and Fuels

    Kerosene and Fuels

    • Kerosene burns effectively at an air/fuel ratio of 15:1.
    • D.E.R.D 2494 is a type of kerosene.
    • Kerosene has more heat energy per gallon and lubricates fuel system components, making it a suitable turbine engine fuel.

    Lubricants and Viscosity

    • Viscosity is the measure of a liquid's resistance to flow.
    • High viscosity index means the oil viscosity will not vary greatly with temperature change.
    • 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 viscosity.
    • Viscosity index is based on the rate of change in viscosity with temperature change.
    • A high viscosity index is desirable in turbine engine oil.

    Functions of Engine Oil

    • Engine oil performs functions in addition to lubricating, including cooling, sealing, preventing corrosion, and cushioning shock loads.

    Oil Types and Characteristics

    • Mineral base lubricants have chemical stability, which is an advantage over vegetable oil base lubricants in aircraft engines.
    • Synthetic oil is usually used in gas turbine engines.
    • An E.P lubricant is required for high tooth pressures and high rubbing velocities in spur type gears.

    Fuel System and Corrosion

    • A biocidal additive is added to fuel to protect integral fuel tanks from corrosion due to micro-biological contamination.
    • Specific gravity of fuel affects aircraft range; a higher specific gravity means a greater weight of fuel for a fixed volume, resulting in a greater range.

    Turbine Engine Performance and Fuel

    • Calorific value is the amount of heat or energy in one pound of fuel.
    • Ignition of fuel depends on both volatility and atomisation.
    • Kerosene is used instead of gasoline because it is less volatile and has good lubrication properties.

    Oil Analysis and Contaminants

    • An oil spectroscope measures contaminants suspended in the oil.
    • Oil sampling by spectrometer analysis is used to detect contaminants in the oil.

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    Description

    Quiz on aircraft fuels and lubricants, including kerosene air/fuel ratios and Prist/Biopor usage in gas turbine powerplants.

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