WorksheetsBGT Mega Quiz
Total questions: 142
Worksheet time: 1hrs 11mins
What is Newtons third law?
For every action there is an equal and opposite reaction
Every object continues in its state of motion or uniform motion in a straight line unless acted upon by an external force
The external forces acting on an object are proportional to the product of its mass and the acceleration produced by the force
Every point mass attracts every other point mass by a force acting along the line intersecting both points
What is the practical application of newtons third law?
Jet thrust
Electric current flow
Chemical reaction rates
Magnetic field generation
The Gas Turbine Engine uses the principle of:
Newton’s Third Law of motion
Creating thrust equal to the weight of the aircraft
Expelling air at the same speed as that of the aircraft
The fluid flywheel
What is Charles law?
At constant pressure, the volume of a given mass of gas is directly proportional to its absolute temperature.
At constant pressure, the volume of a given mass of gas is inversely proportional to its absolute temperature.
At constant volume, the pressure of a given mass of gas is directly proportional to its absolute temperature.
At constant temperature, the volume of a given mass of gas is inversely proportional to its pressure.
What is Boyles law?
At constant temperature, the pressure and the volume of a gas are inversely proportional.
At constant temperature, the pressure and the volume of a gas are directly proportional according to Boyle's law.
Boyle's law states that the volume of a gas decreases as its pressure decreases, regardless of temperature.
Boyle's law only applies to gases that are at very low temperatures.
Which of the following is an example of Potential Energy?
Temperature
Volume
Pressure
Velocity
What property is exhibited by accelerating gas flow?
That the total energy is constant
The gas particles will move at a slower speed than before.
The volume of the gas will decrease.
The gas flow will become more chaotic and disorganized.
Why is the Brayton Cycle in a turbine engine referred to as an open or continuous cycle?
Because intake, compression combustion and exhaust are all occurring at the same time.
Because it doesn't have a fixed amount of working fluid, unlike a closed cycle. In an open cycle, the working fluid is constantly flowing into and out of the system.
Because it takes in air from the atmosphere, uses it to generate power, and then exhausts it back into the atmosphere. This process is continuous and open to the surrounding environment.
Because it doesn't require any external cooling or heat rejection, unlike a closed cycle. Instead, the exhaust gases are expelled directly into the atmosphere, making it a continuous process.
During the Brayton cycle, combustion takes place:
Continuously
Once every revolution
Once every other revolution
Only during the start cycle
Where in a turbofan engine is the pressure highest?
In the diffuser
In the combustion chamber
In the compressor
In the turbine exhaust nozzle
Where in a turbojet engine is the gas velocity the highest?
Exiting the exhaust nozzle.
Exiting the combustion chamber.
Entering the compressor.
Through the diffuser
Where in a turbine engine is the gas temperature highest?
At the flame in the combustion chamber
In the turbine section of the engine where the combustion gases expand and generate thrust.
At the exhaust nozzle, where the hot gases exit the engine and generate propulsion.
At the compressor section of the engine.
A nozzle is said to be “choked” when:
the gas flow through it is subsonic
the gas flow through it reaches its sonic value
the gas temperature rises
the gas flow through it is supersonic
What happens to velocity through a convergent duct, subsonic flow?
Decreases
Increases
Remains the same
Initially decreases and then dramatically increases
How does temperature, density, pressure and velocity of a gas flow vary through a convergent duct at subsonic speeds?
Temperature, density, and pressure reduce and velocity increases.
Temperature, density and velocity increase and pressure reduces.
Temperature and pressure increase, and density and velocity reduce.
Temperature and velocity increase and pressure and density reduce.
How does temperature, density, pressure and velocity of a gas flow vary through a divergent duct at subsonic speeds?
Temperature, density and pressure increase, and velocity reduces.
Temperature, density, and pressure decrease and velocity increases.
Temperature and pressure decrease, density and velocity increase.
Temperature and density increase, pressure, and velocity decrease.
How does temperature, density, pressure and velocity of a gas flow vary through a convergent duct at supersonic speeds?
Temperature, density and pressure increase, and velocity reduces.
Temperature, density, pressure, and velocity increase.
Temperature, density, and pressure decrease, and velocity increases.
Temperature increases, density and pressure decrease, and velocity remains constant.
How does temperature, density, pressure, and velocity of a gas flow vary through a divergent duct at supersonic speeds?
Temperature, density, and pressure reduce and velocity increases.
Temperature, density, and pressure increase and velocity decreases.
Temperature, density, and pressure remain constant, and velocity fluctuates.
Temperature, density and pressure increase, and velocity remains constant.
Air passing through a convergent duct experience:
a decrease in temperature and pressure with an increase in velocity
an increase in temperature and velocity with a decrease in pressure
an increase in temperature and pressure with a velocity decrease
adiabatic expansion
What are the basic sections of a turbine engine?
Intake, compressor, combustion chamber, turbine, and exhaust section
Intake, exhaust, combustion chamber, gearbox, and fuel system section
Intake, compressor, power turbine, exhaust section and fuel system section
Inlet, diffuser, burner, compressor, and afterburner section.
What is the main similarity between a turbine engine and a reciprocating engine?
Both the turbine and reciprocating engines are internal combustion.
Both the turbine and reciprocating engines have the same number of moving parts.
Both engines require the use of magnets to generate power.
They both require the use of a live hamster to operate.
How does the combustion cycle of a turbine engine compare with that of a reciprocating engine?
A turbine engine combustion takes place at a near constant pressure, while in a reciprocating engine combustion takes place at near constant volume.
In a turbine engine, fuel is injected directly into the combustion chamber, whereas in a reciprocating engine, fuel is injected into the intake manifold.
In a turbine engine, the combustion process is slower than in a reciprocating engine.
In a turbine engine, the combustion process is slower than in a reciprocating engine.
What is the main advantage of a turbine engine over a reciprocating engine of the same power output?
The turbine engine has a much higher power to weight ratio than a reciprocating engine of similar power output.
The turbine engine is more reliable than a reciprocating engine of similar power output.
A reciprocating engine is more prone to mechanical failure than a turbine engine of similar power output.
The turbine engine is more difficult to control than a reciprocating engine of similar power output.
What are the main types of turbine engine?
Turboshaft, turboprop, turbojet and turbofan
Turboshaft, ramjet, turbojet and turbofan
Pulsejet, ramjet, turbojet and turbofan
Turboshaft, turboprop, turbocompound and turbofan
What is the functional difference between a turboprop and turboshaft?
A turboprop engine has an output shaft which drives a gearbox for a propeller while a turboshaft engine has an output shaft which drives a gearbox for something other than a propeller, e.g. an helicopters main rotor gearbox.
A turboprop engine has an output shaft which drives a gearbox for a water pump while a turboshaft engine has an output shaft which drives a gearbox for a generator.
Unlike turboprop engines, which are used mainly for passenger and cargo transport, turboshaft engines are primarily used for military purposes.
Turboprop engines are typically more fuel-efficient than turboshaft engines, but they are also less powerful.
The accessory gearbox drive of a gas turbine engine is generally from a bevel gear located at:
N1
N2
Low pressure compressor
None of the above
The combination of a turbine and a compressor is a:
Spool
Crankshaft
Turbo
Jet fan engine
In a twin spool engine:
The LP compressor is connected to the HP compressor.
The HP turbine is connected to the LP compressor, the LP turbine is connected to the HP compressor.
The LP turbine is connected to the LP compressor, the HP turbine is connected to the HP compressor.
The HP turbine is connected to the LP turbine, the HP compressor is connected to the LP compressor.
Gas turbines use for lubrication:
synthetic oil.
mineral oil with additives (compound).
mineral oil straight.
multi-grade 20/50.
The fuel-cooled oil cooler:
heats the oil and cools the fuel
heats the fuel and cools the oil
heats the fuel only
cools the oil only
Magnetic Chip Detectors are fitted in the engine:
to facilitate early detection of cracks in the compressor blades.
to facilitate early warning of cracks in the turbine blades.
to provide a warning of impending failure in the engine bearings.
to prevent a build up of starch in the scavenge oil filter.
The magnetic chip detectors are fitted in:
the pressure line between the pressure pump and the engine.
suction line between the reservoir and the pressure pump.
return line between the engine and the scavenge pump.
return line after the FCOC.
For a pressure relief lubricating system, select the correct statement:
the flow and pressure change with engine speed.
the pressure relief valve is fitted in series with the pump.
the pressure remains the same for all engine operating parameters.
the relief valve opens when pressure has reached the required pressure. Any excess flow is returned by a dedicated line to the base of the engine for scavenging.
Which of the following would be classed as prudent when carrying out Engine Ground Runs?
Only carry out engine runs with a tailwind.
Fit debris guards when running.
Only do ground runs on tarmac.
Only do ground runs on concrete.
In a multispool engine, which spool does the starter rotate?
High pressure spool.
Low pressure spool
Experimental spool
Differential spool
Failure of the engine to light up is shown by:
the failure of the engine to turn and no TGT
low rpm fuel flow indication, and no TGT
TGT increasing but no rpm
no rpm and no TGT
After engine start, the engine igniters are normally deactivated by:
an electric interlock system
a speed switch
the time switch
centrifugal force
The term “self sustaining speed” means that:
the aircraft can roll forward with no further opening of the throttles
the speed from which the engine can accelerate to idle without the help of the starter motor
the speed from which the engine can accelerate to full power within 5 seconds
the engine will run independently of external help
In a twin spool engine self-sustaining speed is normally reached at:
60% N2
60% N1
30% N2
30% N1
In a twin spool engine the typical idle speeds are:
60% N2 25% N1
25% N2 60% N1
40% N2 30% N1
80% N2 45% N1
A “Hung Start” is indicated by:
high EGT - high fuel flow - low rpm
high EGT - idle fuel flow - low rpm
low EGT - idle fuel flow - low rpm
low EGT - high fuel flow - high rpm
A “Hung Start” occurs when:
the engine accelerates but does not light up
the engine lights up but does not accelerate to self-sustaining speed
the engine stabilizes above self-sustaining speed
there is a double igniter failure
What factors may lead to a hot start?
All of these
Low battery voltage
Low air pressure
Air inlet blockage
One indication that a compressor bleed valve has stuck closed at low rpm is:
possible compressor stall
an inability to achieve full power
that bleed air is reduced
that the engine will stop
A gas turbine engine which has both high and low energy ignition systems uses
the high energy system for (i), and the low energy system for (ii):
(i) engine starting (ii) high altitude relighting
(i) high altitude relighting (ii) take-off from contaminated runways
(i) take-off from snowy runways (ii) engine start
(i) take-off from flooded runways
(ii) take-off from snowy runways
The low energy ignition system would be used:
only for starting the engine on the ground.
during take-off from wet runways.
for relight at high altitude.
during a blow out (motoring over) cycle.
Precautionary use of igniters may be necessary during:
flight through heavy tropical rainstorm.
ground running.
flight through sandy conditions.
flight through very dry air.
A relight envelope:
shows the flame stability limits
shows airspeed and altitude limitations for an in-flight restart
shows fuel/air mixture limitations for an in-flight restart
contains the in-flight restart igniter plugs
A Relight is:
the action of restarting a flamed-out engine, usually while airborne
what occurs when the engine drain valve is stuck open
the initiation of the after-burning system
what must be prevented after a “wet start”
A cannular combustion system is:
a set of flame tubes, each of which is mounted in a separate air casing
a set of flame tubes enclosed in a common air casing
one common flame tube enclosed in a common air casing
superior to the annular system because it only requires one igniter
One advantage of an annular combustion chamber system is that:
the diameter of the engine is reduced
there is unrestricted airflow at maximum rpm
there are no flame propagation problems
the air casing area is greater
Swirl vanes in the combustion chamber:
increase the velocity of the airflow
reduce the velocity of the airflow
prevent compressor stall
help to stabilize combustion
Shrouding of stator blade tips is designed to:
prevent tip turbulence
ensure adequate cooling
minimize vibration
prevent tip losses
The purpose of the tertiary airflow created in the combustion chamber is to:
reduce the gas temperature and cool the flame tube
form a toroidal vortex, which anchors and stabilizes the flame
reduce the gas temperature and cool the burner head
ensure complete combustion of the fuel
The air entering the combustion chamber is divided; a small percentage is used in combustion, the rest:
is syphoned off for airframe anti-icing purposes
is used only for cooling the gases before they exit the combustion chamber
is used to cool both the gases exiting the chamber and the walls of the air casing
is used to reduce the oil temperature and cool the turbine blades
What percentage of air entering the internal combustor is used for combustion?
50-60%
65-80%
25-40%
55-70%
When would you select ‘continuous’ ignition?
When volcanic ash clouds have been forecast in the area
Take-off, landing and when encountering significant turbulence or precipitation
Starting and shutting down
When using reverse thrust
Nozzle guide vanes are fitted before the turbine:
to increase the velocity of the airflow.
to decrease the velocity of the gas flow therefore increasing its pressure.
to increase the velocity of the gas flow therefore reducing its pressure.
to increase the temperature of the gas flow.
Over temp in a turbine engine is most critical where?
First stage of turbine assembly
Second stage of turbine assembly
Third stage of turbine assembly
Fourth stage of turbine assembly
The mixture of impulse and reaction blade shape in the average turbine blade is such that:
the inner half is impulse and the outer half is reaction.
the inner half is reaction and the outer half is impulse.
the leading edge is reaction and the trailing edge is impulse.
the trailing edge is reaction and the leading edge is impulse.
The impulse-reaction blade is twisted along its length so that:
there is a greater angle at the base than at the tip.
the gas flow is accelerated through the turbine.
the gas does equal work along the whole of its length.
the gas flow is decelerated through the nozzle guide vanes.
The diameter of the exhaust nozzle is very important. What would be the result of too large a diameter?
expansion is decreased, thrust decreased
expansion is decreased, thrust increased
expansion is increased, thrust decreased
expansion is increased, thrust increased
The main contributory factors which cause creep in turbine blades are:
high temperature and tensile loading.
high rpm and torque loading.
high rpm and high gas speeds.
high temperature and high gas speeds.
Blade creep is:
movement of the turbine blades around the turbine disc.
permanent elongation due to heat and centrifugal force.
temporary expansion due to temperature change.
temporary elongation due to centrifugal forces.
What happens when exhaust velocity is greater than forward speed?
Thrust
Deceleration
Engine overheating
Stress cracking from rapid cooling
What happens at the exhaust of a converging/diverging ducted exhaust?
Pressure decreases, velocity increases
Pressure increases, velocity increases
Pressure increases, velocity decreases
Pressure decreases, velocity decreases
The velocity of the gases in the exhaust unit is held to:
Mach 0.5 to minimize turbulence
Mach 0.75 to optimize the pressure distribution
Mach 0.85 to maximize thrust
Mach 1 to maximize acceleration
The exhaust cone:
straightens the gas flow before it goes into the turbine assembly
prevents the hot gases flowing across the rear turbine face
increases the velocity of the gases
decreases the pressure of the gas
What exhaust system does a high-performance military jet use?
Convergent-divergent
Convergent
Divergent
Divergent-convergent
How do designers reduce noise produced by turbine engines?
Reduce exhaust gas velocity
Increase Exhaust gas temp
Use a convergent divergent duct
Increase exhaust velocity
Use of reverse thrust below the recommended speed may cause:
over stressing of the gear oleos.
ingestion of the exhaust gases and foreign objects.
more fuel to be provided to the burners.
the TGT limit to be exceeded, in which case the reverse thrust lever will return to the forward thrust position.
Before reverse thrust can be selected, the forward thrust lever must be:
pulled back to idle power.
positioned to reverse minimum power.
put back to the reverser deploy position.
positioned to reverse maximum power.
A reverse thrust warning light illuminates:
only when the reverser doors are fully deployed in the reverse thrust position.
when the reverser doors are stowed in the forward thrust position.
when the reverser doors are not stowed in the forward thrust position.
whenever reverse thrust is selected.
Is reverse thrust more efficient at:
High Speeds
Low Speeds
Is equally efficient at all speeds
Is more efficient when the aircraft is flying upside down
How does a turboprop reverse thrust?
By changing blade angle
By diverting the engine's exhaust gases forward
By deploying a tailhook to slow the aircraft on landing
By reducing fuel flow and hydraulic pressure to the CSU
How does a high bypass turbofan commonly reverse thrust in commercial jets?
Flipping a switch that deploys mechanical spoilers on the wings to disrupt airflow and slow the plane
Opening small doors in the engine cowling that redirect some of the engine's exhaust gases forward to create a reverse thrust effect
Deflecting cold bypass air
Rotating the exhaust nozzle so that it points forward, creating reverse thrust by redirecting some of the engine's exhaust gases forward
A big fan engine gets reverse thrust by:
reversing the direction of rotation of the compressor.
deflecting the exhaust gases.
blocking the bypass air.
reversing the hot stream gases.
An aircraft uses clamshell doors for thrust reversal to:
direct the gas flow rearwards.
change the direction of the exhaust gas.
block the flow of exhaust gas.
absorb any change in thrust.
What can occur in AVTUR but not AVGAS at high altitudes?
Water in suspension in fuel freezes forming ice crystals which can block filters.
AVGAS is more prone to vapor lock at high altitudes compared to AVTUR
AVGAS is more prone to corrosion at high altitudes compared to AVTUR
AVTUR has a lower specific gravity than AVGAS, making it more suitable for use at high altitudes.
What is the difference between JP and Jet A fuels?
Jet A is only used in small aircraft, while JP is used in large commercial airliners
JP is a military designation and Jet A is a commercial designation
Jet A is a more environmentally friendly fuel than JP due to its lower sulphur content.
JP is used in colder climates, while Jet A is used in warmer regions.
Fuel is heated to:
prevent waxing
ensure vapour losses are minimized
make it more viscous
make it easier to flow under all conditions
Why are fuel/oil heat exchangers preferred?
A small quantity of oil can heat a large quantity of fuel and stop ice blocking the filter
They increase the mileage of the aircraft by a factor of 100
They can help the engine run on water instead of fuel
A large quantity of oil can heat a small quantity of fuel and stop ice blocking the filter
In a Fuel/Oil heat exchanger, which statement is correct?
Large quantity of fuel flow small quantity of oil flow to allow fuel to draw away more heat from the oil
Always used in combo with air coolers because not enough cooling is given
By giving heat to fuel it increases its calorific value
Turboprops only use air coolers
Fuel booster pumps are situated in
the fuel tanks
the line between the main fuel tanks and the engine
low pressure side of the engine
high pressure side of the engine
The ratio of air to kerosene to give the greatest heat release during combustion is:
45:1
15:1
130:1
12.5:1
how can water be detected in turbine fuel?
Visually
Detector paste
Weight
All of theses
An Ideal intake duct would do what?
Provide constant pressure airflow to the compressor under all flight conditions.
Decrease the engine's initial power output to avoid compressor stall.
Disrupt the airflow to the compressor to increase turbulence.
Increase the temperature of the air entering the engine.
What is the purpose of an intake?
Reduce drag and increase pressure
Increase drag and decrease pressure
Reduce pressure and deliver airflow to the fan/compressor face at an even pressure spread
Increase pressure and redirect airflow onto the high pressure compressor
What does the air intake for a typical high bypass turbo fan do to the pressure and velocity of the air entering the compressor, is the duct convergent or divergent?
Divergent, decreases velocity and increases pressure.
Convergent, decreases velocity and increases pressure.
Convergent, increases velocity and decreases pressure.
Divergent, increases velocity and decreases pressure.
During a climb to altitude drag on the compressor blades:
Increases giving good efficiency.
Increases giving poor efficiency.
Reduces giving good efficiency.
Reduces giving poor efficiency.
The compressor idling speed of an uncompensated gas turbine engine will increase:
at higher ambient temperature
with higher than sea level density
at altitudes lower than sea level
at lower ambient temperature
What happens to airflow pressure and velocity through both rotors and stators in an axial flow compressor?
Velocity decreases through rotors and decreases through stators and increases in pressure through both.
Velocity decreases through rotors and increases through stators and decreases in pressure through both.
Velocity increases through rotors and decreases through stators and increases in pressure through both.
Velocity decreases through rotors and increases through stators and increases in pressure through both.
One stage of an axial flow compressor consists of:
One rotor assembly and one row of stator vanes
One stator assembly and one row of guide vanes
One rotor and one impeller assembly
One impeller and one diffuser assembly
As air passes through an axial flow compressor, a pressure rise takes place in:
the impeller and the diffuser
the rotor blades only
both the rotor blades and the stator vanes
the stator vanes only
The pressure rise across a centrifugal compressor:
occurs in the impeller only
occurs in the diffuser only
is shared almost equally by the impeller and the diffuser
is always greater in the diffuser than in the impeller
A centrifugal compressor turbine compared to an axil flow has the following advantage:
Less frontal area
Lower weight
Less increase per stage
Efficient over a range of mass flow and pressure ratio combinations
The major disadvantage of a centrifugal compressor is that:
it cannot cope with a large mass flow of air
it cannot be used for a turbo jet engine
a larger turbine must be used
it is more prone to damage than the axial flow compressor
An advantage of a centrifugal compressor is that it is:
dynamically balanced
more robust and is easier to manufacture
unaffected by turbulence
able to handle a larger mass of air than an axial flow compressor
The pressure rise across each stage of an axial flow compressor is:
greater than that of a centrifugal compressor
between 1.1 and 1.2 to one
between 3 and 5 to one
twice the inlet pressure
To gain a greater pressure ratio than 4:1:
two centrifugal compressors can be placed in parallel
two centrifugal compressors can be placed in series with each other
the compressor diameter must be reduced
the cascade vanes must be convergent
The compression ratio is:
The ratio between inlet pressure and compressor discharge pressure
The ratio between the compressor inlet pressure and the exhaust outlet pressure
Equal to the number of compressor stages
Is not a real thing
What is the definition of the bypass ratio of a turbofan engine?
The ratio of the mass of the air bypassing the engine core, to the mass of the air passing through the engine core.
It is a key factor in determining the noise level of the engine, as a higher bypass ratio typically results in higher noise emissions.
Is a measure of the efficiency of the engine in terms of how much thrust is generated for a given amount of fuel consumption.
The ratio of the mass of the fuel injected into the engine core, to the mass of the air passing through the engine core.
The ratio of the mass of the oil used for lubrication, to the mass of the air passing through the engine core.
The Bypass Ratio of an engine is the ratio of:
Primary air to tertiary air.
Cold stream air to that flowing through the hot core of the engine.
Exhaust gas pressure to air intake pressure.
Primary air to secondary air.
What are variable inlet guide vanes?
The low pressure compressor
The low pressure turbine
The first stage vanes after the engine inlet
The last stage vanes
The ring of blades which sometimes precede the first rotor stage of an axial flow compressor are called:
the first stage stator blades
variable inlet guides vanes
first stage diffuser blades
nozzle guide vanes
Variable inlet guide vanes:
deflect air past the compressor
adjust the relative airflow position
deflect air past the turbine
induce air into a centrifugal compressor
Compressor blades are twisted from root to tip:
to decrease the pressure
to maintain a correct angle of attack
to reduce the relative airflow
to give added rigidity to the blade structure
What do stators in the compressor do?
Decrease velocity and increase pressure
Increase velocity and increase pressure
Decreases both velocity and pressure
Increases both velocity and pressure
What is the purpose of variable stator vanes?
To control and regulate airflow through a compressor.
To direct airflow onto next compressor blades, used in high compression ratio engines.
To adjust the fuel flow rate in a jet engine.
To provide extra lift during take-off and landing of an aircraft.
The purpose of the diffuser vanes in a centrifugal compressor is to:
increase the charge temperature
convert kinetic energy into pressure energy
convert pressure energy into kinetic energy
increase the air velocity
What happens to airflow through a diffuser?
Pressure and temperature increase and velocity decreases
Pressure and velocity increase and temperature decreases
Temperature increases and velocity and pressure decrease
Pressure and temperature decrease and velocity increases
As air flows through the turbine section energy is removed, what design feature of the turbine section is evidence of this?
Turbine A/A reduces
Turbine diameter increases as air flows through
Turbine casing thickness increases
Turbine stage count increases
Cascade vanes are fitted in which part of the centrifugal compressor?
the air inlet
the outlet elbow
the impeller
the diffuser
The cross-sectional area of the air annulus is reduced as it approaches the combustion chamber:
to maintain the axial velocity of the air toward the combustion chamber
to maintain the volume of the air under rising pressure
to prevent an increase of the velocity of the air under rising pressure
to allow longer blades to be used towards the latter stages of the compressor
Bleed air for engine anti-icing is provided by:
the bleed valves
the turbine stages
the compressor
the combustion chambers
A compressor blade will stall when:
the air axial velocity and rotational speed relationship is disturbed
the mass airflow and speed relationship is constant
the speed of the gas flow through the turbine falls below Mach 0.4
the compression ratio exceeds 10 to 1
Compressor surge will occur when:
all stages are at maximum efficiency
all stages have stalled
all stages are at maximum rpm
there is a partial breakdown of airflow through the compressor
A compressor stall causes:
the vibration level to increase with a decrease in the turbine gas temperature
an increase in the turbine gas temperature and the vibration level
the rotation of the engine to stop suddenly
the airflow through the engine to stop suddenly
From a Pilots perspective, where i a compressor stall most likely to occur?
Bird Strike
Max crosswind landing
High speed cruise at max certified altitude
Lowering flap
What effect will severe icing in the intake have on a high bypass engine?
The axial velocity of the air will decrease with an increase in the angle that the resultant airflow forms with the compressor blades chord line and a possible stall.
The axial velocity of the air will increase with a reduction in the angle of attack of the airflow with the compressor blades and a possible stall.
The axial velocity of the air will decrease with a reduction in the angle of attack of the airflow with the compressor blades and a possible stall.
The axial velocity of the air will increase with an increase in the angle of attack of the airflow with the compressor blades and a possible stall.
In the event of a surge occurring the correct action to be taken is:
to close the throttle quickly
to close the throttle slowly
to open the throttle fully
to close the LP fuel valve
Fuel is regulated on rapid engine acceleration:
to prevent inducing a compressor stall and surge
to prevent detonation in the combustion chambers
because the rapid response of the compressor might cause a flame out
because the cooling effect of too much fuel would cause a drop in pressure in the combustion chamber
What is the first indication of large compressor stall?
Loud Bang
Condensation builds up
Decreasing turbine temperatures
Buffeting wings
What are the indications of a compressor stall?
Popping surging noise, high EGT, fluctuating RPM
A sudden increase in fuel efficiency, low EGT
Smoke emanating from the compressor inlet, fluctuating RPM
The nose pitches down and the aircraft sinks
Bleed valves are automatically opened:
at low engine rpm to prevent the compressor stalling
at maximum rpm to prevent compressor stall
at low rpm to prevent the turbine stalling
during engine acceleration to prevent turbine surge
How are turbine discs cooled?
Oil sprayed on the face of the blade
Air drawn from the compressor
Air drawn from the exhaust
Bypass air redirected to turbines
The jet pipe is insulated from the airframe by:
a combination of cooling air and insulating material
heat insulation materials
a cooling air jacket
semi-conducting geodetic structures
Where is the bleed air for turbine cooling sourced from?
Start of LP compressor as temperature is too high in HP compressor.
From both the HP and LP compressors
From the HP compressor
From the APU
The pressure ratio of a gas turbine engine compressor is:
Equal to the number of compression stages
The ratio between compressor outlet and compressor inlet pressure
The ratio between exhaust inlet and exhaust outlet pressure
Never greater than 5 to 1
The fuel flowmeter is situated:
between HP shut off valve and fuel nozzles
between LP pump and the FCOC
between LP pump and HP pump
just after FCU
In a gas turbine engine oil pressure is measured:
in the engine.
after the pressure pump.
in the return line.
in the FCOC to ensure oil pressure is always above fuel pressure.
In a gas turbine engine oil temperature is measured:
as it leaves the fuel-cooled oil cooler (FCOC).
before entering the engine.
immediately after leaving the engine.
in the engine.
Which of the following statements defines EPR correctly?
Exhaust pipe restriction
Engine pressure ratio
Exhaust pressure reduction
Exhaust pressure ratio
What is the acronym used to describe ratio of turbine outlet pressure to compressor inlet pressure?
EPR
TGT
JPT
EPT
In a turbofan engine, the fan speed is controlled by:
A reduction gear.
The turbine.
A wastegate.
Varying the pitch.
Which of the following best describes the term "fan speed (N1)"?
The speed of the aircraft's engines during take-off
The rpm of the low-pressure compressor/turbine spool and/or fan
The rpm of the high-pressure compressor/turbine spool and/or fan
The speed of the aircraft's landing gear during descent
What indication is taken before the turbine section?
TIT
TGT
EGT
JPT
What factor taken alone will increase thrust?
Increased pressure
Increased temperature
Decreased density
Increased moisture content
Which type is most efficient below 400kts?
Turbo Prop
High Bypass
Low Bypass
Gear Turbofan
Select the correct order of best propulsive efficiency, from low to high airspeed.
High bypass ratio turbojet, Low bypass ratio turbojet, Pure turbojet, Turboprop
Low bypass ratio turbojet, Pure turbojet, Turboprop, High bypass ratio turbojet
Pure turbojet, Turboprop, High bypass ratio turbojet, Low bypass ratio turbojet
Turboprop, High bypass ratio turbojet, Low bypass ratio turbojet, Pure turbojet
A pure turbojet engine gives:
A large acceleration to a small mass of air
A small acceleration to a large mass of air
A large acceleration to a large mass of air
A small acceleration to a small mass of air
What two factors determine/affect a turbojets propulsive efficiency?
Pressure and RPM
Density and Speed
Temp and Speed
Temp and RPM
