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Mod 15: Engines > SAMS Official MCQ > Flashcards

SAMS Official MCQ Flashcards

1
Q

Which of the following is another term for potential energy?

a) Kinetic
b) Heat
c) Pressure

A

c) Pressure

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2
Q

What does Newton’s third law define?

a) Reaction
b) Acceleration
c) Inertia

A

a) Reaction

Newton’s laws:

Inertia 1st law

Acceleration 2nd law

Reaction 3rd law

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3
Q

What takes place when a force acting on a body causes it to move through a distance?

a) Horsepower
b) Kinetic energy
c) Work

A

c) Work

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4
Q

A modern gas turbine engine works on the principal of?

a) Constant Pressure
b) Constant Volume
c) Constant Heat

A

a) Constant Pressure (Brayton cycle)

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5
Q

What is an engine spool?

a) A full compressor stage
b) a full turbine stage
c) A compressor and a turbine on a common shaft

A

c) A compressor and a turbine on a common shaft

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6
Q

Theoretically, if mechanical considerations can be ignored, which engine layout must be the most efficient all-round?

a) Single spool
b) dual spool
c) Triple spool

A

c) Triple spool

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7
Q

What is Specific fuel Consumption?

a) The amount of fuel required to ignite with air in the combustion chamber
b) The amount of fuel burned in one hour to give full thrust
c) The amount of fuel burned in one hour to give one pound of thrust

A

c) The amount of fuel burned in one hour to give one pound of thrust

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8
Q

Which of the following applications would be use a Bellmouth intake?

a) Helicopter Turbo shaft
b) Turboprop
c) Turbofan

A

a) Helicopter Turbo shaft

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9
Q

Engine anti-icing is said to have?

a) One system feeding both engines
b) One system for each engine which cannot feed the other engine
c) One system for each engine if needed can provide anti-icing for the other engine

A

b) One system for each engine which cannot feed the other engine

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10
Q

Define a compressor stage?

a) A compressor rotor linked to a turbine
b) A series of compressor rotors on a common shaft
c) A rotor and stator

A

c) A rotor and stator

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11
Q

Which of the following is not an advantage of using a centrifugal compressor over an axial flow compressor?

a) Small frontal area
b) Can be run at higher speeds
c) Easier to start

A

b) Can be run at higher speeds

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12
Q

Which of the following is used to prevent engine surge?

a) Multi-spool, compressor case cooling
b) Multi-spool, variable bleed valves and variable stator vanes
c) Compressor case cooling, variable stator vanes and variable bleed valves

A

b) Multi-spool, variable bleed valves and variable stator vanes

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13
Q

What is a mid span shroud?

a) A shroud at the base of the blade to guide the airflow into the engine
b) A shroud about 2/3rds up the blade to give it strength
c) A shroud at the tip of the blade to prevent loses

A

b) A shroud about 2/3rds up the blade to give it strength

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14
Q

How are variable bleed valves and stator vanes actuated?

a) Using servo fuel from the FCU
b) Using electrical servos controlled by the EEC
c) Using pneumatic air controlled by the MEC

A

a) Using servo fuel from the FCU

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15
Q

An annular combustor is?

a) A combustor with multiple cans placed evenly around the engine
b) A combustor comprising of a series of can type combustors around the engine
c) A combustor comprising of an inner section and outer section wrapped around the engine

A

c) A combustor comprising of an inner section and outer section wrapped around the engine

(Annular combustor = most efficient)

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16
Q

On what type of engine would a reverse flow annular combustion chamber be used?

a) Turbofan
b) Turbojet
c) Turboshaft

A

c) Turboshaft

(also used on turboprop and some business jets)

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17
Q

What is the Stoichiometric ratio?

a) Ratio of air which is burned in the combustor
b) Ratio of fuel which is burned in the combustor
c) The most efficient ratio in which kerosene burns in air

A

c) The most efficient ratio in which kerosene burns in air

Stoichometric ratio = 15:1

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18
Q

Which stage will turbine blade fracture occur during it’s life time?

a) Tertiary Creep
b) Primary Creep
c) Secondary creep

A

a) Tertiary Creep

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19
Q

What is blade stagger?

a) A twist in the blade from root to tip
b) The way in which the blades are fixed in the disc relation to one another
c) The distance the blade is kept at from the next stator stage

A

a) A twist in the blade from root to tip

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20
Q

What is the turbine blade manufacturing method giving the best resistance to fatigue cracking?

a) Single Crystal
b) Directionally Solidified
c) Cold Forged

A

a) Single Crystal

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21
Q

What are the most common methods of securing turbine blades to disc?

a) By TIG welding
b) They have ‘‘Fir Tree’’ or ‘‘De Laval Bulb’’ roots
c) They are high temperature riveted to the disc periphery

A

b) They have ‘‘Fir Tree’’ or ‘‘De Laval Bulb’’ roots

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22
Q

What type of turbine do small Auxillary Power Units use?

a) Reaction blade axial
b) Radial inflow Turbines
c) Multi-stage impulse reaction axial

A

b) Radial inflow Turbines

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23
Q

What is the purpose of the convergent duct at the end of the Jetpipe?

a) To produce the thrust reaction by maximising pressure rise as the gases exit
b) To prevent an over rapid exit of the gases, which would reduce thrust generation
c) To convert pressure and heat energy into maximum kinetic energy

A

c) To convert pressure and heat energy into maximum kinetic energy

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24
Q

What kind of nozzle is used by a supersonic aircraft?

a) A conventional convergent nozzle
b) A divergent-convergent nozzle
c) A convergent-divergent nozzle

A

c) A convergent-divergent nozzle

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25
Q

Which method of thrust reverser is most used on modern Fan Engines?

a) Clamshell doors
b) Translating sleeves and blocker doors
c) Bucket doors

A

b) Translating sleeves and blocker doors

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26
Q

What are the most common additives in an aviation jet fuel?

a) Tetra-ethyl lead and methanol
b) Diluted oil and anti-icing additive
c) Anti-icing and anti-microbiocidal agents

A

c) Anti-icing and anti-microbiocidal agents

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27
Q

Why would a gas turbine lubricant need to have good anti-lacquering characteristics?

a) To prevent viscosity change with temperature
b) To prevent sludging
c) To prevent premature oxidation and colour change of the oil

A

b) To prevent sludging

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28
Q

What type of oil is used on modern turbo-prop engines?

a) High viscosity mineral oil
b) High viscosity synthetic oil
c) Low viscosity synthetic oil

A

b) High viscosity synthetic oil

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29
Q

In an engine oil system, what are the two main categories of pressure systems?

a) Unregulated pressure and regulated pressure
b) Pressure regulated and full flow
c) Full flow and partial flow

A

b) Pressure regulated and full flow

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30
Q

Where in a ‘‘Hot Tank’’ system would the oil cooler be situated?

a) In the scavenge return line to the tank
b) In the pressure line, after the pressure pump
c) In the tank delivey line, before the pressure pump

A

b) In the pressure line, after the pressure pump

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31
Q

In an oil tank, what is used to remove bubbles from returning oil?

a) A de-aerator
b) The oil is sprayed onto the sides of the tank
c) Th anti-surge baffles

A

a) A de-aerator

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32
Q

What is used to detect the presence of Ferrous debris in a scavenge return?

a) Magnetic chip detectors
b) Coarse mesh oil strainers
c) Last chance oil fitters

A

a) Magnetic chip detectors

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33
Q

If a fuel system is not of the Hydro-mechanical type, what type will it be?

a) Electro-Mechanical
b) Semi-Mechanical Digital control
c) Full Authority Digital Engine Control

A

c) Full Authority Digital Engine Control (FADEC)

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34
Q

What are the two main types of high pressure fuel pump in use in modern gas turbine fuel systems?

a) Centrifugal and Vane type
b) Plunger and Gear type
c) Gear and Centrifugal type

A

b) Plunger and Gear type

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35
Q

What is the overall Air/Fuel ratio of a 1:1 low ratio by-pass engine?

a) 15:1
b) 60:1
c) 120:1

A

a) 15:1 (Stoichometric ratio)

36
Q

How does a FADEC system control fuel flow in a fuel metering valve?

a) Torque motor
b) A synchro
c) A P&D valve

A

b) A synchro

37
Q

How are High Pressure nozzle guide vanes cooled?

a) With fan air
b) With low pressure compressor air
c) With high pressure delivery air

A

c) With high pressure delivery air

38
Q

What is the most effective means of cooling Turbine Blades?

a) Single pass internal convection cooling
b) Multiple internal convection cooling
c) Internal cooling with external film cooling

A

c) Internal cooling with external film cooling

39
Q

Why are air starters used extensively to start modern gas turbine engines today?

a) They are cheaper to manufacture than electric starters
b) They have a longer life span than electric starters
c) They have a better power to weight ratio than electric starters

A

c) They have a better power to weight ratio than electric starters

40
Q

Between what % RPMs would fuel usually be turned on during a jet engine start-up?

a) Between 25% and 33% RPM
b) Between 18% and 25% RPM
c) Between 10% and 17% RPM

A

b) Between 18% and 25% RPM

41
Q

Where a double output ignition system is employed, what aircraft voltages are used to supply the 4 joule and 20 joule ignition outputs?

a) Both are 115V ac
b) 4 joule is supplied by 28V dc and 20 joule is supplied by 115V ac
c) 4 joule is supplied by 115V ac and 20 joule is supplied by 28V dc

A

c) 4 joule is supplied by 115V ac and 20 joule is supplied by 28V dc

42
Q

How are High-Tension ignition leads protected from overheating?

a) They are located in cool areas of the core engine
b) They are cooled by Fan air fed into their shrouds
c) They are wrapped in Asbestos flexi-wrap

A

b) They are cooled by Fan air fed into their shrouds

43
Q

Which of the following only contain Primary engine instruments?

a) EPR, N1, Vibration and N2
b) N1, Oil pressure, EGT and N2
c) N1, EGT, Fuel temp and EPR

A

a) EPR, N1, Vibration and N2

44
Q

Which two types of RPM sensors are in common use on modern gas turbine engines?

a) Synchro generators and Piezo electric
b) Tachometer generator and Phonic wheel
c) Phase multiplexer and accelerometers

A

b) Tachometer generator and Phonic wheel

45
Q

How is EPR calculated on an engine?

a) PT7 divided by PT2
b) PT7 multiplied by PT2
c) PT2 divided by PT7

A

a) PT7 divided by PT2

PT2 = intake pressure

PT7 = Turbine Discharge Pressure

46
Q

What metal is commonly used in an oil temperature sensor?

a) Chromel
b) Copper
c) Nickel

A

c) Nickel

47
Q

Which Turbo-prop layout carries with it the problem of the propeller’s inertia?

a) The twin spool layout
b) The free turbine
c) The coupled turbine

A

c) The coupled turbine

48
Q

What design feature renders many Turbo-prop engines much more compact in overall length than they would otherwise be?

a) Axial flow compressors
b) Free turbines
c) Reverse flow combustion chambers

A

c) Reverse flow combustion chambers

49
Q

What type of reduction gear is used by most large modern Turboprops?

a) Helical-cut parallel spur gears
b) Straight-cut parallel spur gears
c) Epicyclical gear train

A

c) Epicyclical gear train

50
Q

When compared with a Turbo-prop, what is missing from a Turbo-shaft engine’s equipment?

a) The speed governor
b) The propeller
c) The temperature limiter

A

b) The propeller

51
Q

What is the main advantage of a turbo-shaft engine?

a) It is most efficient at a constant RPM
b) It is lighter than any other type of torque producing engine
c) It has higher torque at extremely low RPM

A

a) It is most efficient at a constant RPM

(APU = constant RPM engine = Turboshaft)

52
Q

Where are most APU’s located in modern aircraft?

a) In the aft cargo compartment
b) In the wheel well area
c) In the tail section

A

c) In the tail section

53
Q

How are modern APUs normally started?

a) By a small electric starter using battery voltage
b) by use of the aircraft’s built-in inertia starter
c) By low-pressure air source and lightweight starter motor

A

a) By a small electric starter using battery voltage

54
Q

Are powerplant assemblies interchangeable from one mounting point to another?

a) Yes
b) No
c) Only on twin engined aircraft

A

b) No

55
Q

What is the main disadvantage of a tail mounted engine?

a) Aerodynamic efficiency of the rudder is decreased
b) It is never possible to obtain a really good intake shape
c) It is harder to get at for maintenance

A

c) It is harder to get at for maintenance

56
Q

In order to prevent damage to a set of engine cowlings, what procedure must be adopted?

a) The opening/closing order should be as per the MM
b) A row of latches should be closed ‘‘outside to in’’
c) Aluminium alloy cowlings must be braced in a jig when removed in order to prevent distortion

A

a) The opening/closing order should be as per the MM

57
Q

What manufacturer of fire detector uses a pneumatic or pressure type detector?

a) Walter Kidde
b) Fenwall
c) Systron Donner

A

c) Systron Donner

58
Q

What is the advantage of continuous condition monitoring?

a) Engine servicing can be planned in advance
b) Engine deterioration can be detected and engine replacement scheduled in advance
c) Engine service can be increased

A

b) Engine deterioration can be detected and engine replacement scheduled in advance

59
Q

What type of medium is used during a Compressor cleaning with abrasive material?

a) Fine sand
b) Ground up plastic pellets
c) Ground walnut shells and apricot pips

A

c) Ground walnut shells and apricot pips

60
Q

At what pressure should the water solution be kept at when carrying out a running wash?

a) 15 - 20 psi
b) 35 - 40 psi
c) 45 - 55 psi

A

a) 15 - 20 psi

61
Q

The pressure ratio of a gas turbine engine compressor is:

a) Equal to the number of compressor stages
b) The ratio between compressor outlet and compressor inlet pressure
c) The ratio between exhaust inlet and exhaust outlet pressure
d) Never greater than 5 to 1

A

b) The ratio between compressor outlet and compressor inlet pressure

62
Q

One stage of an axial flow compressor consists of:

a) One rotor assembly and one row of stator vanes
b) One stator assembly and one row of guide vanes
c) One rotor and one impeller assembly
d) One impeller and one diffuser assembly

A

a) One rotor assembly and one row of stator vanes

63
Q

The pressure rise across each stage of an axial flow compressor is:

a) Greater than that of a centrifugal compressor
b) Between 3 and 5 to one
c) Twice the inlet pressure
d) Between 1.1 and 1.2 to one

A

c) Twice the inlet pressure

64
Q

The ring of blades which sometimes precede the first rotor stage of an axial flow compressor is called:

a) The first stage stator blades
b) The inlet guide vanes
c) First stage diffuser blades
d) Nozzle guide vanes

A

a) The first stage stator blades

65
Q

Shrouding of stator blade tips is designed to:

a) Prevent tip turbulence
b) Ensure adequate cooling
c) Minimise vibration
d) Prevent tip losses

A

c) Minimise vibration

66
Q

The attachment of blades to the compressor disc:

a) Allows slight movement to relieve stress concentration
b) is rigid
c) Prevents them being contaminated by the atmosphere
d) Allows slight movement because of the different expansion rates of the blades and the disc, which would otherwise cause center line closure

A

a) Allows slight movement to relieve stress concentration

67
Q

Compressor blades are designed to produce:

a) A given pressure and velocity rise
b) A constant flow over the engine speed range
c) A steady velocity with a pressure rise over the engine speed range
d) Turbulent flow into the combustion chamber

A

b) A constant flow over the engine speed range

68
Q

A compressor blade will stall when

a) The air axial velocity and rotational speed relationship is disturbed
b) The mass air flow and speed relationship is constant
c) The speed of the gas flow through the turbine falls below 0.4 Mach
d) The compression ratio exceeds 10 to 1

A

a) The air axial velocity and rotational speed relationship is disturbed

69
Q
  1. Cascade vanes are fitted in which part of the centrifugal compressor?
    a) The air inlet
    b) The outlet elbow
    c) The impeller
    d) The diffuser
A

c) The impeller

70
Q

When gases pass through a convergent duct their:

a) Velocity and temperature increase and their pressure decreases
b) Their velocity increases and their temperature and pressure decreases
c) Their velocity decreases and their temperature and pressure increase
d) They expand adiabatically

A

b) Their velocity increases and their temperature and pressure decreases

71
Q

Select the correct order of best propulsive efficiency, from low to high airspeed

a) High by-pass ratio turbo jet, Low by-pass ratio turbo jet, Pure turbo jet, Turbo-prop
b) Low by-pass ratio turbo jet, Pure turbo jet, Turbo-prop, High by-pass ratio turbo jet
c) Pure turbo jet, Turbo-prop, High by-pass ratio turbo jet, Low by-pass ratio turbo jet
d) Turbo-prop, High by-pass ratio turbo jet, Low by-pass ratio turbo jet, Pure turbo jet

A

b) Low by-pass ratio turbo jet, Pure turbo jet, Turbo-prop, High by-pass ratio turbo jet

72
Q

The highest pressure in a gas turbine engine occurs:

a) Between the compressor and the combustion chamber
b) In the combustion chamber
c) In the Jet pipe
d) At the P1 probe

A

a) Between the compressor and the combustion chamber

73
Q

In a turbo-fan engine, the fan speed is controlled by:

a) A reduction gear
b) A waste gate
c) The turbine
d) Varying the pitch

A

c) The turbine

74
Q

In a high ratio by-pass engine

a) All of the air goes through both the low and high pressure compressors
b) Not all the air goes through the high pressure compressor
c) Not all the air goes through the low pressure compressor
d) All the air goes through the high pressure compressor

A

b) Not all the air goes through the high pressure compressor

75
Q

Modular construction

a) is only used on turbo-prop engines
b) cannot be used on high ratio engines
c) Has a weight saving function
d) Enables malfunctioning sections of the engine to be changed without changing the whole engine

A

d) Enables malfunctioning sections of the engine to be changed without changing the whole engine

76
Q

On a cold day, the idle speed of a gas turbine engine which has no fuel control unit compensation

a) Is unaffected by temperature
b) Will increase
c) Will decrease
d) Will increase by no more than 4%

A

c) Will decrease

77
Q

The By-Pass Ratio of an engine is the ratio of:

a) Primary air to Tertiary air
b) Cold stream air to that flowing through the hot core of the engine
c) Exhaust gas pressure to air intake pressure
d) Primary air to secondary air

A

b) Cold stream air to that flowing through the hot core of the engine

78
Q

The Gas Turbine Engine uses the principle of:

a) Newton’s Third Law of motion
b) Creating thrust equal to the weight of the aircraft
c) Expelling air at the same speed as that of the aircraft
d) The fluid flywheel

A

a) Newton’s Third Law of motion

79
Q

The addition of heat in a combustion chamber allows a:

a) Large expansion at a substantially constant pressure
b) Large expansion at a constant volume
c) Large expansion at a decreasing static pressure
d) Minimum expansion at a constant volume

A

a) Large expansion at a substantially constant pressure

80
Q

12 In a divergent duct

a) The pressure decreases and the temperature and velocity increases
b) The pressure, velocity and temperature increases
c) The pressure and temperature increases and the velocity decreases
d) The pressure decreases, the temperature increases and the velocity remains constant

A

c) The pressure and temperature increases and the velocity decreases

81
Q

In a twin spool engine

a) The L.P compressor is connected to the H.P compressor
b) The H.P turbine is connected to the L.P compressor, the L.P turbine is connected to the H.P compressor
c) The L.P turbine is connected to the L.P compressor, the H.P turbine is connected to the H.P compressor
d) The H.P turbine is connected to the L.P turbine, the H.P compressor is connected to the L.P compressor

A

c) The L.P turbine is connected to the L.P compressor, the H.P turbine is connected to the H.P compressor

82
Q

A By-Pass Ratio of 5:1 means that:

a) 5 pounds of air is by-passed for every 10 entering the engine intake
b) 5 pounds of goes through the H.P compressor for every 10 pounds that enters the intake
c) 10 pounds of air goes through the by-pass for every 5 pounds that enters the intake
d) 5 pounds of air is by-passed for every 1 pound that goes through the hot core of the engine

A

d) 5 pounds of air is by-passed for every 1 pound that goes through the hot core of the engine

83
Q
A

The rearmost turbine

84
Q
A

Cools the combustion chamber and therefore increases thermal efficiency

85
Q
A

Turbo-prop engine comes from the turbine exhaust

86
Q
A

A small acceleration to a small mass of air

87
Q
A

Continuously

Mod 15: Engines (28 decks)

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