Exam 4

Question 1

With respect to the combustion process, how do turbine engines differ from reciprocating (piston) engines?

1. In turbine engines combustion takes place at near constant velocity, while in a reciprocating engine combustion takes place at an increasing temperature.
2. In turbine engines combustion takes place at near constant pressure, while in a reciprocating engine combustion takes place at a constant volume.
3. In turbine engines combustion takes place at near constant temperature, while in a reciprocating engine combustion takes place at an increasing pressure.
4. In turbine engines combustion takes place at near constant volume, while in a reciprocating engine combustion takes place at an increasing pressure.

Answer 1

B

Question 2

Typically, the fuel system in a turbine engine will contain filters just before and just after the main fuel pump. The high pressure filter will contain a special safety feature. What is it?

1. A fusable plug that melts if the temperature gets too high.
2. A bypass system that will open if the filter becomes blocked.
3. A bypass system that will operate when the fuel flow is low.
4. A bypass system that operates during engine start to provide higher fuel flow to the nozzles.

Answer 2

B

Question 3

The practical application of Newton’s third law, as it applies to a turbofan engine, is called:

1. power.
2. RAM effect.
3. thrust.
4. momentum.

Answer 3

C

Question 4

Multiple, separate interconnected chambers within a common air casing, encircling the turbine shaft, describes:

1. a can combustion chamber.
2. a can-annular combustion chamber.
3. an annular combustion chamber.
4. axial flow combustion chamber.

Answer 4

B

Question 5

Injecting water/methanol into the combustion chamber of a turboprop engine:

1. increases the temperature of the air, thereby decreasing the density and therefore the weight (mass) of the gas flow through the engine.
2. cools the air, thereby increasing the density and therefore the weight (mass) of the gas flow through the engine.
3. increases the velocity of the air, thereby increasing the weight (mass) of the gas flow through the engine.
4. increases the pressure of the air, thereby decreasing the density and therefore the weight (mass) of the gas flow through the engine.

Answer 5

B

Question 6

What are the three stages of turbine blade creep?

1. First, second and third.
2. Status, gradual and final.
3. Primary, secondary and tertiary.
4. Initial, developed and terminal.

Answer 6

C

Question 7

What is Boyle’s Law?

1. For gas at a constant pressure, the volume of a given mass of gas is directly proportional to its absolute temperature.
2. For gas at a constant volume, the pressure of a given mass of gas is directly proportional to its absolute temperature.
3. For a gas at a constant temperature, the pressure in a closed vessel will be inversely proportional to its volume.
4. Equal volumes of ideal or perfect gases, at the same temperature and pressure, contain the same number of particles, or molecules.

Answer 7

C

Question 8

Which of the following is most likely to cause a compressor stall?

1. A bird ingestion (strike).
2. Starting the engine with a significant tailwind.
3. Starting the engine at an airfield with a high pressure elevation.
4. Landing in gusty crosswind conditions.

Answer 8

A

Question 9

What is the primary function of the nozzle diaphragm?

1. To increase the pressure of the exhaust gases.
2. To decrease the velocity of heated gases flowing past this particular point.
3. To prevent choking of the heated gases flowing past this particular point, thereby reducing the possibility of turbine and compressor stall.
4. To maximise the velocity of the gas exiting the combustion section ,and to direct the gases at the optimum angle onto the turbine blades

Answer 9

D

Question 10

Which part of a turbine engine is most susceptible to damage as the result of an over-temp condition?

1. The compressor inlet guide vanes.
2. The first stage turbine nozzle.
3. The exhaust duct.
4. The diffuser.

Answer 10

B

Question 11

What is the definition of compressor pressure ratio?

1. The ratio of stage one outlet pressure to stage two inlet pressure.
2. The ratio of the final stage outlet pressure to first stage inlet pressure.
3. The ratio of combustion chamber outlet pressure to the engine inlet pressure.
4. The ratio of the inlet pressure to the first stage compressor outlet pressure.

Answer 11

B

Question 12

How are modern turbine blades cooled in a turbofan engine?

1. Oil is splashed over them.
2. Bleed air from the compressor is blown over and/or through them.
3. Fan air is blown over and through them.
4. Secondary combustion air is blown over and through them

Answer 12

B

Question 13

How is the residual temperature of the exhaust gases utilised?

1. Exhaust gases are used for airframe ice protection systems.
2. It is not used at all, but rather it is lost to the atmosphere.
3. Exhaust gases are used for engine ice protection systems.
4. On turboprops the temperature of the exhaust gases can contribute to forward thrust, but on helicopters they serve no useful purpose

Answer 13

B

Question 14

Which of the following is NOT a symptom of a compressor stall/surge?

1. Fluctuating RPM.
2. A surging/popping noise.
3. Increasing turbine temperature.
4. Increasing EPR

Answer 14

D

Question 15

How do clamshell reversers function?

1. By cascade vanes in the nacelle surrounding the bypass duct opening to allow the cold fan air to flow outward and forward.
2. By blocker doors external to the exhaust duct moving to blank off the hot exhaust gases redirecting them forward.
3. By blocker doors inside the exhaust duct moving to blank off the hot exhaust gases redirecting them forward.
4. By blocker doors in the bypass duct moving to blank off the cold fan air redirecting it forward.

Answer 15

C

Question 16

For a gas at a constant temperature, the pressure in a closed vessel will be inversely proportional to its volume. This is an expression of:

1. the second law of thermodynamics.
2. Charles’ Law.
3. Boyle’s Law.
4. Newton’s Fourth Law

Answer 16

C

Question 17

What results when the velocity of the jet of exhaust gas is greater than the current aircraft speed?

1. Thrust.
2. Temperature decreases.
3. Drag.
4. Momentum increases.

Answer 17

A

Question 18

Which of the gas flows from a turbofan engine is used to generate reverse thrust?

1. Combustion gases from reverse flow engines.
2. The cold stream flow from the bypass duct.
3. The hot exhaust gas from the core flow.
4. Compressor flow by reversing the angle of the fan blades.

Answer 18

B

Question 19

Which type of compressor can be described as having multiple stages of rotating aerofoil blades and fixed vanes, capable of large mass flow capacity, with high efficiency?

1. An axial flow compressor.
2. A centrifugal compressor.
3. A centripetal compressor.
4. A radial compressor.

Answer 19

A

Question 20

Which of the following actions would be the correct if you experienced unacceptably slow acceleration of RPM on a turbine engine during start?

1. Increase the fuel flow.
2. Open the thrust lever/throttle to the idle position.
3. Shut off the fuel supply and discontinue the start cycle.
4. Open the bleed valves to increase air flow through the compressor.

Answer 20

C

Question 21

A double stage centrifugal compressor typically has a compression ratio of up to:

1. 1:1.
2. 15:1.
3. 20-30:1.
4. 10:1

Answer 21

B

Question 22

What does the term reverse flow mean when used to describe the combustion section of a turbine engine?

1. Reverse flow means that the combustion gases are vectored forward to aid deceleration during landing or on a rejected takeoff.
2. Reverse flow means that combustion gases are directed through a cooling section so that the fan can be mounted externally at the rear of the engine.
3. Reverse flow means that the gas reverses its direction during the combustion process.
4. Reverse flow means that raw fuel is injected into the combustion gases for reheat (after burning)

Answer 22

C

Question 23

What are the two main types of intake on turbofan engined aircraft?

1. Centreline and offset.
2. Divided and pitot.
3. Shielded and unshielded.
4. Convergent and divergent

Answer 23

B

Question 24

What type of oil pump is generally utilised on turbine engines?

1. A variable displacement type.
2. A sliding vane type.
3. A piston and plunger type.
4. A gear type

Answer 24

D

Question 25

Over-temperature in a turbine engine is considered the most critical:

1. in the flame tube or combustion chamber.
2. at the propelling nozzle.
3. at the first stage turbine assembly
4. in the area between the engine casing and nacelle structure

Answer 25

C

Question 26

What is the ideal air/fuel ratio for combustion in a turbine engine?

1. 20:1
2. 30:1
3. 15:1
4. 10:1

Answer 26

C

Question 27

During take-off in a turbine powered aircraft, correct engine operating technique would be for the pilot to advance the power lever until:

1. the engine torque limit is reached, regardless of other indications.
2. the turbine temperature limit is reached, regardless of other indications.
3. maximum fuel flow is reached, regardless of other indications.
4. the first of the torque or the turbine temp is reached

Answer 27

D

Question 28

How is RPM typically measured in a turboshaft engine?

1. By measuring compressor outlet pressure, since compressor outlet pressure is proportional to engine RPM.
2. By utilising a sensor which measures fan blade passage over a pick-up.
3. By utilising an electronic counter which measures the ignition pulses.
4. By utilising an AC generator, three phase independent electrical system and synchronous motor.

Answer 28

D

Question 29

There are three general types of combustion chamber. The most easily serviced is totally external to the engine, the second is a dual ring system and the third is an efficient combination of the two others. Which of the following lists the three types, in the order described?

1. Can-annular, Annular and Can.
2. Can, Can-annular and Annular.
3. Can-annular, Can and Annular.
4. Can, Annular and Can-annular

Answer 29

D

Question 30

Why is it necessary for a starting system to uniformly accelerate the turbine engine from rest up to a speed at which the gas flow through the turbine provides sufficient torque to “take over”?

1. To give a hotter start but reduced time spent at higher temperatures and therefore a longer engine life.
2. To prevent the build-up of fuel in the combustion chamber from the time the engine starts turning.
3. To give a cooler start and longer engine life.
4. To give the combustion chambers the correct air flow for the combustion process to continue acceleration to idle speed

Answer 30

D