Propulsion Exam Questions

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Propulsion Exam Questions

The term “propulsion” means to push forward or drive an object forward. Propulsion systems consist of a source of mechanical power and a propulsor – or means of converting this power into propulsive force. What do you know about the concept?


Questions and Answers
  • 1. 
    Direct fuel injection is often used in aero piston engines, in preference to float chamber carburettors. Which of these statements applies to the direct fuel injection system?
    • A. 

      The fuel does not have to be vaporised

    • B. 

      It cannot operate inverted

    • C. 

      A throttle butterfly is unnecessary

    • D. 

      There is no choke on the intake

  • 2. 
    In this diagram of an inverted 4-cylinder in-line aero engine, a basic component is shown both in its proper place inside the engine and also, for clarity, enlarged and outside the engine. The component is:
    • A. 

      The connecting rod assembly

    • B. 

      The cam shaft

    • C. 

      The tappet assembly

    • D. 

      The crankshaft

  • 3. 
    In this diagram of a simple carburettor, which arrow (W, X, Y or Z) points to the main jet?
    • A. 

      W

    • B. 

      X

    • C. 

      Y

    • D. 

      Z

  • 4. 
    In the modified 4-stroke cycle, ignition takes place:
    • A. 

      Just before TDC on the compression stroke

    • B. 

      Just before TDC on the power stroke

    • C. 

      At TDC on the power stroke

    • D. 

      At TDC on the compression stroke

  • 5. 
    Which of these is a turbojet engine?
    • A. 

      Olympus 593

    • B. 

      Spey

    • C. 

      Tyne

    • D. 

      Pegasus

  • 6. 
    The purpose of gudgeon pins in a piston engine is to:
    • A. 

      Hold the sparking plugs in place

    • B. 

      Attach the pistons to their connecting rods

    • C. 

      Fasten together the two halves of the crankcase

    • D. 

      Retain the valves in their guides

  • 7. 
    “After-burning” in a jet engine involves burning additional fuel in the:
    • A. 

      Jet pipe

    • B. 

      Turbine

    • C. 

      Combustion chamber

    • D. 

      Compressor

  • 8. 
    What is the purpose of the “fins” which are arranged about the cylinder and cylinder head of an air-cooled engine?
    • A. 

      To direct air through the engine compartment

    • B. 

      To reduce the weight of the engine

    • C. 

      To support the engine cowlings

    • D. 

      To allow heat to dissipate rapidly

  • 9. 
    On a variable pitch propeller, the largest obtainable pitch angle is known as:
    • A. 

      Fine pitch

    • B. 

      Take-off pitch

    • C. 

      Optimum pitch

    • D. 

      Coarse pitch

  • 10. 
    In an aircraft propeller system the function of the constant speed unit (CSU) is to:
    • A. 

      Maintain a selected engine speed within the power available

    • B. 

      Feather the propeller

    • C. 

      Retard the ignition timing

    • D. 

      Increase the mixture strength

  • 11. 
    The 2 main methods of cooling piston aero engines are liquid cooling and air cooling. Which of the following is an advantage that air cooling has over liquid cooling?
    • A. 

      Promotes longer life between engine overhauls

    • B. 

      Much cheaper to make

    • C. 

      Can hold the engine at a more even temperature

    • D. 

      Engine can be more easily streamlined

  • 12. 
    When the airflow over the propeller blades of a failed engine keeps the propeller turning, this is known as:
    • A. 

      Windmilling

    • B. 

      Propeller braking

    • C. 

      Reverse thrust

    • D. 

      Contra rotating

  • 13. 
    In a piston aero engine, the purpose of the distributor is to distribute:
    • A. 

      High voltage electrical impulses to the cylinders

    • B. 

      Oil to all parts of the engine

    • C. 

      The correct mixture of air and fuel to the cylinders

    • D. 

      Cooling air to all parts

  • 14. 
    “Blade twist” in a propeller helps to:
    • A. 

      Make feathering possible

    • B. 

      Make the blade stronger and lighter

    • C. 

      Reduce noise levels

    • D. 

      Even out the thrust along the length of the blade

  • 15. 
    Which of these statements applies to a propeller that has been “feathered”?
    • A. 

      Its leading edges are facing forwards in the direction of flight

    • B. 

      It is operating at its maximum rotational speed

    • C. 

      Its leading edges are facing 90O to the direction of flight

    • D. 

      It is producing maximum power

  • 16. 
    What is the purpose of the scavenge pump in the dry sump lubrication system of a piston engine?
    • A. 

      To scavenge containments from the oil

    • B. 

      To transfer oil from the crankcase to the oil tank

    • C. 

      To direct oil into the pressure chamber

    • D. 

      To ensure that all engine components are lubricated

  • 17. 
    What is the benefit of using liquid (as opposed to air) to cool an aircraft piston engine?
    • A. 

      A steady operating temperature will be more easily maintained

    • B. 

      The engine will be lighter

    • C. 

      The engine will be simpler

    • D. 

      The engine will be less costly to produce

  • 18. 
    Which of the following describes a magneto as used in an aircraft’s piston engine?
    • A. 

      A secondary compass system

    • B. 

      A dynamo to produce the spark for the spark plugs

    • C. 

      A mechanical pump for circulating

    • D. 

      An instrument for metering fuel flow

  • 19. 
    For which of these applications is the turboshaft engine most suited?
    • A. 

      Low-speed fixed-wing aircraft

    • B. 

      Helicopters

    • C. 

      High altitude reconnaissance aircraft

    • D. 

      High-speed combat aircraft

  • 20. 
    In a piston engine, what force is used to return the valves onto their seats after they have been opened?
    • A. 

      Gravity

    • B. 

      Coil springs

    • C. 

      Cams pressing on the valve stems

    • D. 

      Atmospheric pressure

  • 21. 
    Which of these statements refers to turbo-chargers? They are:
    • A. 

      Fitted to turbo-fans only

    • B. 

      Driven by exhaust gases

    • C. 

      Driven by gears from the engine

    • D. 

      Fitted to turbojet engines only

  • 22. 
    Which of these is a turboprop engine?
    • A. 

      Adour

    • B. 

      Dart

    • C. 

      RB 211

    • D. 

      Spey

  • 23. 
    In the modified 4-stroke cycle, which of these is valve lead
    • A. 

      Inlet valve closing after the piston has passed BDC

    • B. 

      Inlet and exhaust valves are open together

    • C. 

      Exhaust valves clsoing after the piston has passed TDC

    • D. 

      Exhaust valve opening before the piston reaches BDC

  • 24. 
    The function of the turbine in a turbojet engine is to:
    • A. 

      Vapourise the fuel as much as possible

    • B. 

      Drive the gas stream into the atmosphere

    • C. 

      Energise the gas steam

    • D. 

      Drive the compressor