ULTILEARN PISTON ENGINE PROPULSION QUESTIONS
PISTON ENGINES
Engine layouts
A / B / C / D1. 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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
81. In this diagram of a propeller, what is angle 'b'
Pitch angle
Fine angle
Prop angle
Blade angle
1