ULTILEARN PISTON ENGINE PROPULSION QUESTIONS

PISTON ENGINES

Engine layouts

A B C D

1. Which of the above engine layouts is an inline 4 layout?

A

B

C

D

2. What type of layout is the above piston engine?

V Twin

Inline 4

Vee 8

Vee 4

1

3. The piston engine layout above is known as?

Inline 3

Inline 4

Inline 5

V-Twin

4. The illustration above is what type of layout for a piston engine?

V Twin

Inline 4

Vee 4

Flat 4

5. This illustration shows the typical layout for a light aircraft engine. What is this layout called?

Inline 4

Vee 4

Staggered 4

Flat 4

2

Operation

6. In a two stroke piston engine, how many times does the crankshaft rotate to complete one cycle?

3 4 2 1

7. In a Wankel engine, for every rotation of the triangular piston, how many times does the crankshaft rotate?

Once

Twice

Three times

Four times

8. In a four stroke engine, at what nominal crankshaft angle does the spark initiate combustion?

30 degrees after BDC

30 degrees after TDC

30 degrees before BDC

30 degrees before TDC

9. What is the firing order in a four cylinder piston engine?

1, 3, 2, 4

1, 3, 4, 2

1, 4, 3, 2

1, 2, 3, 4

10. In a four stroke piston engine, what speed does the cam shaft rotate at in relation to the crankshaft?

Twice crankshaft speed

Crankshaft speed

Half crankshaft speed

A quarter Crankshaft speed

3

11. In a 4-stroke piston engine, what is the force which closes the exhaust and inlet valves?

Suction

Gravity

A spring

A pushrod

12. In a piston engine, ineffective crank angle occurs in the region of:

BDC only

Neither BDC or TDC

TDC only

Both BDC and TDC

13. What is the correct sequence for the operating cycle of a four stroke piston engine?

Induction, compression, power, exhaust

Induction, power, compression, exhaust

Power, induction, compression, exhaust

Induction, compression, exhaust, power

14. In a piston engine, what forces the inlet and exhaust valves closed?

A spring

Gravity

A pushrod

Suction

15. In a four stroke piston engine, how many times does the crankshaft rotate to complete one cycle

3 4 2 1

4

16. In the modified 4-stroke cycle, which of these is valve lead?

Inlet and exhaust valves are open together

Exhaust valve opening before the piston reaches BDC

Inlet valve closing after the piston has passed BDC

Exhaust valve closing after the piston has passed TDC

17. In order for compression to occur in a piston engine which of the inlet valves and exhaust valves need to be closed?

The inlet valves

None

The exhaust valves

All the inlet and exhaust valves

Components

18. The purpose of gudgeon pins in a piston engine is to:

Attach the pistons to their connecting rods

Fasten together the two halves of the crankcase

Hold the sparking plugs in place

Retain the valves in their guides

19. A piston engine camshaft has a lobe for each valve, what is the difference in the low diameter and the high part of the lobe called?

High spot

Valve lift

Pushrod bump

Lift point

5

20. In the illustration above, four parts are labelled. Which part is the gudgeon pin?

W X Y Z

21. In the illustration above, four parts are labelled. Which part is the crankshaft main bearing?

W X Y Z

22. In the illustration above, four parts are labelled. Which part is the connecting rod?

W X Y Z

23. The crankshaft is mounted in the engine on a series of mainline bearings. How many main line bearings are there in a four cylinder engine?

3 4 5 6

24. In the illustration above, four parts are labelled. Which part is the valve?

W X Y Z

6

25. In the illustration above, four parts are labelled. Which part is the camshaft?

W X Y Z

26. In this diagram of a piston engine's valve mechanism, the arrow X points to:

A scraper

A cam

A pushrod

A tappet

Supercharging

27. What is the primary function of a supercharger on a piston engine?

To increase the pressure in the induction manifold

To ensure the battery is charged throughout the full range of engine speeds

To speed up the extraction of exhaust gases

To make use of unburnt fuel in the exhaust gases

28. How is the air compressor driven in a position engine turbocharger?

By belt of gears from the engine crankshaft

By an electric motor

By the exhaust gases

By ram air pressure

7

29. What is the main function of a supercharger when fitted to a piston engine?

It delivers a stronger spark to the sparking plugs

It increases the amount of lubricating oil delivered to the bearings

It increases the amount of air and fuel delivered to the cylinders

It ensures that the batteries are always fully charged

30. How is the air compressor driven in a piston engine supercharger?

By the engine crankshaft

By an electric motor

By the exhaust gases

By ram air pressure

31. Which of these statements, about an exhaust-driven turbocharger, is true?

It operates best at high engine speeds

It operates as soon as the throttle is opened

It operates best at low engine speeds

It is more effective than an engine-driven supercharger at increasing the power output

Ignition

32. The distributor includes two mechanisms, centrifugal weights and a pressure diaphragm, to advance the spark timing. What are these mechanisms for respectively?

To advance the timing for engine speed and engine intake manifold pressure

To advance the timing for engine speed and air pressure

To advance the timing for engine temperature and air pressure

To advance the timing for engine pressure and exhaust temperature

8

33. In electrical terms, what is meant by EMF?

Electro Motive Force

Easy Motive Force

End Motive Force

Exceptional Motive Force

34. Which of the following describes a magneto as used in an aircraft's piston engine?

A secondary compass system

A mechanical pump for circulating fuel

An instrument for metering the fuel flow

A dynamo to produce the spark for the spark plugs

35. In a magneto, what is one purpose of the condenser (or capacitor)?

Make the primary current flow evenly

Make the secondary current flow evenly

Reduce erosion at the spark plug gaps

Reduce pitting of the contact breaker points

36 Which of the following accurately describes the purpose of a magneto in an ignition system?

To produce the energy for the spark at the spark plugs

To circulate fuel

To sense fuel flow

To circulate oil

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

At TDC on the compression stroke

At TDC on the power stroke

Just before TDC on the compression stroke

Just before TDC on the power stroke

9

38. In a breakerless electronic ignition system, what components indicate the position of the crankshaft to the ignition control unit?

The coil packs

The alternator

The distributor timing disc and sensor

The valve timing belt

39. In a petrol engine, what basic maintenance is required to maintain healthy operation of the spark plugs?

Clean the electrodes and body

Set the electrode gap

Check the plug ceramic insulator for cracks

All of the above

40. In a magneto system, where is the power for the spark generated?

In the contact breaker points

In the coil secondary windings

In the condenser

In the coil primary windings

41. In a piston aero engine, the purpose of the distributor is to distribute?

High voltage electrical impulses to the cylinders

Oil to all parts of the engine

Cooling air to all external parts

The correct mixture of air and fuel to the cylinders

10

42. In a magneto system, the primary and secondary windings are incorporated within the magneto. Where are the primary and secondary winding in a dynamo/alternator system?

In the distributor

In the dynamo

In the alternator

Fuel System

43. In a simple 4-stroke piston engine, which of these air-to-fuel ratios (by weight) would be the normal mixture?

15:01

09:01

06:01

12:01

44. What ratio (by weight) of fuel to air should the carburettor normally supply in a piston engine?

02:01

01:02

15:01

01:15

45. In a fuel injection system, how is the fuel atomised?

Fuel pressure through small spray nozzle

Fuel pressure through fuel mixer

Fuel temperature through small jet orifice

Fuel pressure through a needle valve

11

46. In a two stroke piston engine, how is the fuel air mixture supplied to the combustion chamber?

By an electrical pump

By a mechanically driven pump

By atmospheric pressure

By the piston moving down the cylinder

47. Where are the fuel tanks located in a freight or passenger type aircraft?

In the fuselage

In the tail

the wings In

In the fin and underwing tanks

Lubrication

48. There are two basic types of oil system, a wet sump system and a dry sump system. In which type of engine application is a dry sump system typically used?

Aircraft and high performance cars

Tractors and construction vehicles

Road cars

Military transport vehicles

49. Oil specifications include the property of viscosity. What does high viscosity mean?

Synthetic type oil

A thinner consistency

Mineral type oil

A thicker consistency

12

50. What is the purpose of the scavenge pump in the dry-sump lubrication system of a piston engine?

To direct oil into the pressure chamber

To ensure that all engine components are lubricated

To scavenge contaminants from the oil

To transfer oil from the crankcase to the oil tank

51. In a piston engine, far more oil is circulated than is needed to reduce friction alone. Why?

To lubricate the pressure pump

To cool the engine internally

To produce a full splash effect

To ensure the scavenge pump is always fed

52. Oil is used for lubricating engine parts to reduce friction. What other function does the oil system provide?

Ensures the fuel pump runs smoothly

Removes friction generated heat

Provides the engine cooling system fluid

Mixes with the fuel to assists in efficient combustion

53. The mainline bearings in a piston engine are shell type bearings, how is the oil delivered to these bearings?

By direct jet

As the crankshaft rotates, the big ends splash through the oil in the sump

By pressure feed through internal drillings and pipes

By jet and splash

13

Cooling

54. 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?

Much cheaper to make

Promotes longer life between engine overhauls

Can hold the engine at a more even temperature

Engine can be more easily streamlined

55. In a liquid cooled engine, what is the purpose of the thermostatic valve?

It prevents cooling in the radiator until the driver/pilot selects it open

It prevents cooling in the radiator until the engine has warmed up

It prevents heating in the vehicle interior until the engine has warmed up

It allows the coolant to be cooled until the engine is hot, they it closes

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

The engine will be simpler

The engine will be less costly to produce

A steady operating temperature will be more easily maintained

The engine will be lighter

57. What is the purpose of the fins which are arranged about the cylinder and cylinder head of an air-cooled engine?

To direct air through the engine compartment

To allow heat to dissipate rapidly

To reduce the weight of the engine

To support the engine cowlings

14

58. The two methods of cooling piston engines are liquid cooling and air-cooling. Which of the following is an advantage that air-cooling has over liquid cooling?

Air cooled engines are much cheaper to make

Air cooling can hold the engine at a more even temperature

Air cooling promotes longer life between overhauls

Air cooled engines are more powerful

59. The two methods of cooling piston engines are liquid cooling and air cooling. Which of the following is an advantage that liquid cooling has over air cooling?

Liquid cooled engines are much cheaper to make

Liquid cooling can hold the engine at a more even temperature

Liquid cooled engines do not need overhauling

Liquid cooled engines are more powerful

60. The main 2 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?

Can hold the engine at a more even temperature

Promotes longer life between engine overhauls

Engine can be more easily streamlined

Much cheaper to make

61. What/How is the thermostatic valve operated?

Closed by heat, opened by a spring

Manually closed, opened by a spring

Opened by heat, closed manually

Opened by heat, closed by a spring

15

Carburation

62. When a piston engine is accelerating, the purpose of an accelerator pump when fitted to the carburettor is:

Prevent the mixture from becoming weak

Decrease the air pressure in the float chamber

Increase the air pressure in the float chamber

Prevent the mixture from becoming rich

63. What is the purpose of the accelerator pump fitted to the carburettor of a piston engine? When the engine is accelerating it:

Increase the air pressure in the choke tube

Decrease the air pressure in the choke tube

Prevents the mixture from becoming too rich

Prevents the mixture from becoming too weak

64. In this diagram of a simple carburettor, what does the arrow point to?

Float

Throttle valve

Main jet

Choke tube

16

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

X Z Y W

66. 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?

There is no choke on the intake

It cannot operate inverted

The fuel does not have to be vaporised

A throttle butterfly is unnecessary

67. The arrow X points to a device which is often incorporated into the carburettor of a piston aero engine. What is its function?

Prevents the fuel/air mixture from becoming richer as the aircraft climbs

Encourages good atomisation of the fuel

Prevents the fuel/air ratio from becoming richer as the throttle valve is opened

Supplies extra fuel when needed for acceleration

17

68. In normal running conditions, what component in a carburettor controls engine speed?

The throttle valve

The accelerator pump

The choke valve

The float chamber

69. In an electronic common rail fuel injection system, how is the fuel flow to the engine controlled?

By varying the fuel pressure

By varying the jet orifice size

By varying the jet orifice size and fuel pressure

By varying the time the fuel injector valves are open

PROPELLORS

70. Propeller braking involves:

Turning the blades beyond fine pitch

Feathering the propeller

The selection of coarse pitch

The selection of fine pitch

71. What is another term for coarse pitch?

Faired

Feathered

Folded

Flayed

18

72. The blade angle on a propeller is varied from a coarse angle at the tip. This is called:

Blade translation

Adjustable pitch

Variable pitch

Blade twist

73. Why were constant speeding variable pitch propellers developed?

To reduce the work load of a pilot

To prevent the engine developing too much power

To increase engine power

To cool the engine more efficiently

74. In an aircraft propeller system the function of the constant speed unit (CSU) is to?

Retard the ignition timing

Feather the propeller

Maintain a selected engine speed within the power available

Increase the mixture strength

75. When a propeller rotates, what two motions produce the helix angle?

Forward speed and blade angle

Forward speed and climb rate

Forward speed and descent rate

Forward speed and engine RPM

76. A variable-pitch propeller is said to be feathered when:

The leading edges are at 90 degrees to the direction of flight

It is in fully coarse pitch

The leading edges face forward in the direction of flight

It is in fully fine pitch

19

77. In the propeller control unit, how is engine speed and propeller pitch controlled?

By a spring balanced with bob weight centrifugal force

By a spring balanced with bob weight spring force

By a spring balanced with bob weight hydraulic force

By a spring balanced with bob weight electrical force

78. Blade twist in a propeller helps to?

Make the blade stronger and lighter

Reduce noise levels

Make feathering possible

Even out the thrust along the length of the blade

79. How does the propeller governor know the rotational speed of the propeller?

The governor receives an electrical speed signal

The governor receives a hydraulic speed signal

The governor receives an air speed signal

The governor receives a mechanical speed signal

80. On a variable-pitch propeller, the largest obtainable pitch angle is known as:

Coarse pitch

Take-off pitch

Optimum pitch

Fine pitch

20

81. In this diagram of a propeller, what is angle 'b'

Pitch angle

Fine angle

Prop angle

Blade angle

21