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ATPL AASA > BGT > Flashcards

BGT Flashcards

1
Q

You would expect to find the highest gas velocity in a turbojet engine

A

At the end of the exhaust nozzle

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2
Q

The purpose of a diffuser in a gas turbine engine is to:

A

Lower velocity and raise pressure

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3
Q

The correct statement regarding the variations of MSL full throttle thrust of a jet engine is:

A

Thrust decreases as air temperature increases

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4
Q

You would expect to find the highest gas pressure in a turbojet engine:

A

In the diffuser

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5
Q

You would expect to find the highest gas temperature in a turbojet engine:

A

In the combustion chamber

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6
Q

The engine core of a turbofan refers to:

A

The compressor, combustion chambers, turbines and exhaust

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7
Q

The maximum thrust output of a turbojet engine will increase with:

A

A decrease in ambient air temperature

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8
Q

The effect an increase in altitude alone will have on the Low Pressure compressor of a gas turbine engine if constant thrust is maintained is:

A

RPM will decrease

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9
Q

A pure turbojet engine in comparison to a turbofan engine has:

A

No bypass air

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10
Q

Subsonic gas flow decreases in velocity and increases in pressure when flowing through:

A

A divergent duct

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11
Q

Ram effect

A

Raised the thrust output of a jet engine as aircraft speed increases

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12
Q

In passing through the turbine section of a pure turbojet engine:

A

Gas pressure reduces, velocity increases and temperature decreases

*think of a turbine as convergent

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13
Q

Tertiary creep in a turbine blade of a gas turbine engine means:

A

Blade creep to the point where it would be detrimental to continue to run the engine

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14
Q

Gas turbine engine compressor stall may be caused by:

A

Unstable airflow through the compressor

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15
Q

The maximum gas pressure in a gas turbine is obtained:

A

At the compressor exit

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16
Q

For a given RPM, thrust output from a gas turbine engine will be greatest:

A

At MSL under ISA conditions

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17
Q

If a compressor blade stall occurs in a gas turbine engine:

A

The smooth flow of air over the blading breaks away and causes an interruption of airflow through the engine

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18
Q

The purpose of variable inlet guide vanes in a gas turbine engine is to:

A

Prevent compressor blade stall during operation off design RPM

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19
Q

Turbojet aircraft range increases as altitude increases toward the optimum FL because at high altitude:

A

The engine can operate at design RPM to maintain an efficient wing angle of attack

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20
Q

The use of bleed air from a gas turbine engine compressor for anti-icing equipment will result in:

A

An increase in the gas temperature, reduced thrust and an increase in SFC

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21
Q

Maximum gas pressure in a gas turbine engine is found:

A

Between the final compressor stage and inlet to the combustion chamber

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22
Q

The main reason for a limit on the maximum gas temperature in a gas turbine engine is:

A

To prevent overheating of the turbine

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23
Q

Burning fuel in the combustion chambers of a gas turbine engine is necessary to:

A

Increase the volume and velocity of the gases

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24
Q

On leaving the compressor in a gas turbine engine, the air passes through:

A

Divergent ducts which lower the velocity and raise the pressure of the air

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25
Q

When an aircraft is parked overnight, to reduce fuel tank condensation you would:

A

Keep the tanks as full as possible

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26
Q

In a free turbine turboprop engine, the propeller is driven by:

A

Only the rear LP turbine(s)

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27
Q

The action which should be taken if a gas turbine compressor begins to stall during engine acceleration on start up is:

A

Shut off the fuel supply and maintain starter motor rotation

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28
Q

The term SFC means

A

Units of fuel used per unit of thrust per hour

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29
Q

Some turbojet engine turbine blades shrouded at the tips to:

A

Prevent gas leaking past blade tips, increase rigidity and reduce vibration

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30
Q

The fuel flow in a jet engine is increased. Thrust increases because exhaust gas:

A

Velocity increases

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31
Q

The times the surge bleed valve is open and closed during normal gas turbine engine operation are:

A

Open from idling to nearly design RPM then closed up to max RPM

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32
Q

The propulsive efficiency of a turboprop decreases with an increase in speed because:

A

Of compressibility effects on the blades

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33
Q

The gas turbine cycle (Brayton) is called an open or continuous cycle because:

A

All events are occurring at the same time

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34
Q

A modest increase in speed in a slow flying jet aircraft leads to a small initial decrease in maximum thrust available because:

A

The difference between exhaust and intake velocities is reduced

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35
Q

Pressure through the combustion chambers in a gas turbine engine:

A

Is constant or falls slightly

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36
Q

To prevent melting of the turbine wheels, the hot gases from the combustion chambers in a gas turbine engine are cooled by:

A

Air

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37
Q

Engine Pressure Ratio (EPR) is the ratio of:

A

Engine compressor inlet pressure to jet pipe pressure

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38
Q

When climbing in a jet engine aircraft, the engine parameter which would stay constant if the thrust lever setting remained unchanged is:

A

RPM

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39
Q

Thrust is produced in a jet engine by:

A

The force required to accelerate a mass of air through the engine

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40
Q

Fuel boost pumps in a jet aircraft fuel system are usually located in:

A

The fuel tanks

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41
Q

Most modern turbofan engines have 2 or more spools (shafts) because:

A

This allows compressors to run closer to their ideal RPM

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42
Q

An ideal jet engine air intake delivers air to the compressor with:

A

No turbulence and pressure higher than ambient

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43
Q

Air that is bypassed in a turbofan engine:

A

Does not go through the compressor

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44
Q

One compressor bleed outlet is for cabin pressurisation and air conditioning. Another is used to:

A

Prevent compressor stall and surge when operating off design RPM

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45
Q

The row of stator blades after each row of rotating compressor blades is designed to:

A

Convert kinetic energy to pressure energy

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46
Q

The turbofan is more efficient than the turbojet because:

A

It accelerates a relatively large mass of air to a low velocity

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47
Q

Apart from bigger stronger fan blades, a turbofan enjoys better FOD protection than a pure turbojet because:

A

Most of the air bypasses the engine

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48
Q

A turbofan is not as efficient as a turboprop at low speeds. This is because the turbofan has:

A

A lower air mass accelerated to a higher velocity

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49
Q

A turboprop cannot operate at the high speeds of a turbofan because the turboprop has:

A

Shockwaves at the prop tips at high Mach number

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50
Q

A free turbine turboprop uses a smaller starter motor than other turboprops because:

A

Only the engine core is rotated for starting

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51
Q

One way to increase the performance of a jet engine is to:

A

Increase the engine operating temperatures

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52
Q

Of a turbofans total air intake, 20% passes through the core. This bypass ratio is nearest to:

A

4:1

*20% through the engine, 80% bypasses the engine
20/80 = 1/4
But because it’s asking about bypass first = 4:1

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53
Q

Turboprops are usually designed for what type of flying:

A

Low speed, short routes

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54
Q

An aircraft may need to dump fuel, to ensure that the total fuel supple is not dumped:

A

Use of standpipes in the fuel dumping system

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55
Q

A turbofan produces less thrust at takeoff than a smaller size turboprop because

A

Turboprop is very efficient at modestly accelerating a large mass of air

56
Q

With a constant speed turboprop engine, power output is controlled by fuel flow. The pilot controls this by:

A

Control of the fuel flow control unit

57
Q

The primary engine power gauge of a turboprop is the:

A

Torque gauge

58
Q

One reason why jet aircraft use kerosene and not AVGAS is that kerosene has:

A

A higher flashpoint

59
Q

An APU of a 767 may be operated:

A

Whenever it is required

60
Q

The purpose of the fuel system filter bypass in a gas turbine engine is:

A

To ensure fuel flow even though the filter is blocked

61
Q

If a turbojet thrust reverse unlocked light comes on during flight:

A

The situation is potentially critical, show down the engine if yaw, loss of airspeed or buffet is detected

62
Q

The main reason for stating an upper limit to fuel temperature is:

A

To ensure vapour lock (vapour release) does not occur

63
Q

An APU auto-shutdown will not be caused by:

A

Underspeed

*Will auto-shutdown for overspeed, low oil pressure and fire

64
Q

The document in which you would find the optional fuels approved for a particular aircraft is:

A

In the aircraft flight manual

65
Q

The additives normally found in F35 jet fuel (Jet A1) used in Australia is:

A

None

66
Q

The engine instrument which would not be found on a turbofan aircraft is:

A

Torque

(Because N1=tq)

67
Q

An APU does not directly provide:

A

Hydraulic pressure

68
Q

The inflight problem a turbine engine with low flight idling RPM may have is:

A

Flame out on descent

69
Q

A desirable quality of jet fuel is:

A

Lubricant properties

*And high flash point

70
Q

Air turbine starters for gas turbine engines normally:

A

Cannot be used if the APU or another engine or compressed air source is not available

71
Q

The safeguards used to prevent inadvertent engine thrust reverser deployment in flight are:

A

An auto stow mechanism and mechanical and electrical interlocks and isolation valves which prevent full reverse thrust unless the thrust levers are at idle and the reversers are fully deployed

72
Q

In a gas turbine engine with a free power turbine:

A

The free power turbine shaft is independent of the other engine spools

73
Q

The advantages of an axial flow compressor compared to a centrifugal flow compressor of the same frontal area in a gas turbine engine are:

A

Higher pressure ratios and greater mass airflow

74
Q

A torque meter in a turboprop aircraft is required for the operation of the:

A

Autofeather system

75
Q

A transport jet aircraft is filled to max. Fuel by volume (full tanks) with kerosene of a lower specific gravity. Compared to using kerosene with a higher specific gravity, the max range of the aircraft with the low SG will be:

A

Reduced

76
Q

Concerning the connection of turbines and compressors in a gas turbine engine:

A

The LP compressor is connected to the LP turbine

77
Q

Regarding the measurement of temperature in a gas turbine engine

A

JPT measures jet pipe gas temperature

*EGT = exhaust gas
ITT = inter turbine
TOT = turbine outlet

78
Q

With regard to thermal ice protection systems using engine bleed air:

A

When used on an engine intake, thermal ice protection should be regarded as anti-icing

79
Q

One of the limitations of air starting system on a gas turbine engine is:

A

The requirement for an APU, another engine or a ground unit to provide compressed air

80
Q

The purpose of a propeller brake on a turbo prop is:

A

To prevent the propeller windmilling when the engine is shut down and to allow the engine to be run at idle power on the ground without turning the propeller

81
Q

The function of a safety couple in a turboprop engine is:

A

To decouple the engine from the gearbox in the event of a prop overspeed

82
Q

The function of a negative torque system in a turboprop us to:

A

Increase the propeller blade angle to prevent the turbine from being driven by the propeller

83
Q

The EPR gauge in a jet aircraft measures:

A

The pressure ratio between the exhaust air and intake (ambient) air

84
Q

The N1 gauge in a turbofan engine indicates:

A

Fan RPM

85
Q

As a turbofan powered aircraft climbs through the tropopause, thrust will:

A

Reduce at a greater rate compared to below the tropopause

86
Q

The use of bleed air from a gas turbine engine for various services will result in most loss of performance during:

A

Take off and climb

87
Q

In a turboprop installation, the term power plant refers to:

A

The gas turbine engine, gearbox and propeller

88
Q

The reverse thrust system on a turbojet aircraft has interlocks to prevent:

A

Full reverse thrust until the reversers are in the full reverse position

89
Q

With reference to a gas turbine engine:

A

TGT is the temperature of the gas between the turbine stages

90
Q

A 727 is maintaining a constant flight level and the TAS is increased from 180kts to 460kts. Thrust available at maximum thrust will:

A

Decrease then increase

91
Q

The fuel flow transmitter in the fuel system of a large jet transport category aircraft is located:

A

At the outlet from the fuel control unit

92
Q

Turbojet engine compressor blade angle of attack is primarily determined by:

A

Engine RPM and TAS

93
Q

As the thrust levers of a turbojet engined aircraft are advance for takeoff:

A

Fuel flow increases causing a higher EGT and increased RPM

94
Q

The pressure rise in the centrifugal compressor of a gas turbine engine occurs in:

A

Both the impeller and the diffuser

95
Q

Gas turbine engine compressor blades do not usually require thermal anti ice protection because:

A

The centrifugal action of the rotor blades prevents ice accretions

96
Q

On a wet day takeoff in a jet engined aircraft, the ignitor plugs may be selected to continuous ignition. In this case the characteristics of the spark will be:

A

Low value joules at a high voltage to preserve the ignitor plugs and the ignition unit

*High and voltage both have ‘g’ in them so they go together

97
Q

With an air turbine starter system on a large modern jet engine, the starter is disengaged:

A

Automatically by the starter clutch at a predetermined RPM

98
Q

The primary purpose of the APU in large jet transport category aircraft is for:

A

Electrical and pneumatic supply on the ground

99
Q

The design feature which is not an advantage of the annular combustion chamber design in a modern gas turbine engine compared to other multi chamber designs is:

A

Greater structural integrity

*Advantages are: improved combustion efficiency
Less cooling air required
Elimination of flame propagation problems within chambers
Reduced wight and cost
Compact

100
Q

A particular turbine fuel has a specific gravity of 0.8 at a given temperature. A temperature rise of 20o will result in a calorific value (energy) for the fuel which is:

A

The same energy value as for the original temperatures per KG of fuel

101
Q

The function of the torque meter in a turboprop powered aircraft is to:

A

Monitor shaft output power

102
Q

A probable result of a hot start in a gas turbine engine is:

A

Torching of the exhaust section

103
Q

Regarding the measurement of temperature in a gas turbine engine:

A

JPT measures jet pipe temperature

*EGT is exhaust gas temp
ITT is inter turbine temp

104
Q

The ram air effect on a turbojet engine results in a conversion of:

A

Kinetic energy in the airstream into pressure

105
Q

Boost pumps in the fuel system of a large jet transport category aircraft are generally:

A

Gear type or impeller type

106
Q

Regarding the functioning of the reverser thrust system on a high bypass turbo fan engine:

A

Blocker doors are used to divert the cold stream

107
Q

The takeoff run of a turbofan powered aircraft will be increased by:

A

Increased altitude

*lower altitude means higher density so shorter takeoff run

108
Q

The use of bleed air on takeoff in a large turbojet engined aircraft will result in:

A

Higher EGT

109
Q

The effect of a change in temperature on the specific gravity of AVTUR is:

A

SG decreases as temperature increases

110
Q

The ideal air:fuel ratio for a turbine engine is:

A

15:1

111
Q

The section of the APU which supplies compressed air to start the main engines on a large jet transport aircraft is:

A

The compressor

112
Q

The purpose of the air shroud on an atomised type (duplex) fuel spray nozzle in the combustion chamber of a gas turbine engine is:

A

To reduce carbon deposits around the nozzle tip and cool the nozzle

113
Q

The function of variable inlet guide vanes in a gas turbine engine is:

A

To prevent compressor blade stall when the engine is operating at low RPM

114
Q

The gas turbine engine component which acts to straighten the airflow before exiting the engine is:

A

The rear turbine exhaust cone support struts in the jet pipe

115
Q

Turbofans and turbojets are preferred over turboprops for speeds over about 350kts because:

A

Turboprops have reduced propulsive efficiency at high speeds

116
Q

Reverse thrust on a turbofan or turbojet is not as effective as forwards thrust because:

A

The angle of the reverse thrust is not directly opposing the aircraft motion

117
Q

The most common method of ice protection used on the propellers of a turboprop aircraft is:

A

Electrical

*Think of king air - check electrical amps in run ups so it’s electrical

118
Q

The following statements correctly lists the differences between kerosene and wide cut turbine aviation turbine fuel:

A

Kerosene has a lower volatility than wide cut fuel

119
Q

The most common type of starter motor found on large modern jet transport aircraft turbine engines is:

A

Air turbine starters

120
Q

The effect on the maximum static thrust output of a turbojet engine at MSL with changes in ambient temperature and pressure is:

A

Static thrust decreases with an increase in temperature and decreased pressure

121
Q

The effect on the maximum static thrust output of a turbojet engine at MSL with changes in ambient temperature and pressure is:

A

Static thrust decreases with an increase in temperature and decreased pressure

122
Q

The function of bleed valves in the compressor of a gas turbine engine is:

A

To increase the mass airflow over the early compressor stages at low engine RPM

123
Q

The changes in the gas flow within the combustion chamber of a gas turbine engine are:

A

Volume increases, temperature increases, pressure decreases or remains constant

124
Q

Air in the combustion chamber of a gas turbine engine is slowed to:

A

Reduce possibility of a flame out

125
Q

Turbine fuel requires:

A

High calorific value

126
Q

A particular turbofan engine has 3 shafts. N1 refers to:

A

The slowest shaft

127
Q

An advantage of the centrifugal flow compressor over the axial flow compressor is:

A

It’s cheaper and more robust

*Axial is more efficient

128
Q

A symptom of a hung start with a gas turbine engine is:

A

No rise in RPM

129
Q

Operating a jet engine at design RMP will give the:

A

Minimum SFC

130
Q

Jet engine design RPM is:

A

Slightly less than maximum RPM

*92-98%

131
Q

With regard to transport category aircraft fuel systems, the true statement is:
A. Fuel gauges provide the only method of accurately determining fuel on board before commencing a flight
B. Measurement of fuel quantity on board may only be conducted on a level surface
C. Fuel on board may be determined by use of readings from dipsticks combined with tables and a sight gauge to correct for uneven terrain
D. Fuel used meters are the only reliable method of accurately determining fuel on board before commencing a flight

A

Fuel on board may be determined by use of readings from dipsticks combined with tables and a sight gauge to correct for uneven terrain

132
Q

The purpose of standpipes serve in an aircraft fuel system is:

A

They prevent unintentional dumping of the entire fuel tank contents

133
Q

The ideal air:fuel mixture ratio for kerosene is:

A

15:1

134
Q

The component of a gas turbine engine which directs the airflow into the compressor is:

A

The inlet guide vanes

135
Q

The function of interconnectors between multiple combustion chambers in a gas turbine engine is:

A

Equalise operating pressure and allow combustion propagation between chambers

ATPL AASA (3 decks)

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