Propulsion Exam Questions
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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?
- 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?]( "In this diagram of a simple carburettor, which arrow (W, X, Y or Z) points to the main jet?")
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
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