BGT Multi-Choice Flashcards
Q. Which of the following additives are commonly used in Jet A1?
A. Anti-toxin.
B. Anti-serum.
C. Anti-microbiocodal.
D. Anti-inflammatory.
C. Anti-microbiocodal.
Q. Over-temperature in a turbine engine is considered the most critical:
A. in the flame tube or combustion chamber.
B. in the area between the engine casing and nacelle structure.
C. at the first stage turbine assembly
D. at the propelling nozzle.
C. at the first stage turbine assembly
Q. Why does the pressure and temperature increase during the compression section? A. Because potential and kinetic energy increase.
B. Because the compressor forms a divergent duct.
C. Because volume increases.
D. Because total internal energy decreases.
A. Because potential and kinetic energy increase.
Q. How do the fuel classification Jet A and Jet A1 differ from those classified JP?
A. The Jet A and A1 have the same flash point as the JP fuels.
B. The Jet A and A1 have a lower freezing point than the JP fuels.
C. The Jet A and A1 are civilian classifications and the JP are military.
D. The Jet A and A1 have a higher degree of purity than the JP fuels.
C. The Jet A and A1 are civilian classifications and the JP are military.
Q. Which of the following is NOT a symptom of a compressor stall/surge? A. Increasing turbine temperature. B. Increasing EPR. C. A surging/popping noise. D. Fluctuating RPM.
B. Increasing EPR.
Q. What is the function of the bypass system in fuel filters?
A. To open when the fuel flow is low.
B. To open if the filter becomes blocked.
C. To close after start and open again on shutdown.
D. To open when the engine is starting or accelerating from low power/rpm.
B. To open if the filter becomes blocked.
How are turbine discs usually cooled?
A. By feeding bypass air into the hot gas stream beyond the combustion outlet.
B. By feeding a supply of high pressure air from the compressor onto the face of the disc.
C. By spraying oil onto the face of the disc.
D. By feeding a low pressure air supply from the exhaust through and onto the face of the disc.
B. By feeding a supply of high pressure air from the compressor onto the face of the disc.
Q. Which part of a turbine engine is most susceptible to damage as the result of an over-temp condition? A. The diffuser. B. The first stage turbine nozzle. C. The compressor inlet guide vanes. D. The exhaust duct.
B. The first stage turbine nozzle.
Q. What are the two exhaust gas flows of a turbofan engine called?
A. Convergent and divergent.
B. Hot stream and cold stream.
C. External and internal.
D. Donut and core.
B. Hot stream and cold stream.
Q. The primary function of air seals within a turbine engine is to:
A. prevent ram air from escaping the air inlet system.
B. prevent turbine outlet air from escaping the nozzle system.
C. pressurise labyrinth and carbon seals.
D. pressurise the compressor rotor area and cool the hot section areas.
C. pressurise labyrinth and carbon seals.
Q. How is the residual temperature of the exhaust gases utilised?
A. Exhaust gases are used for airframe ice protection systems.
B. Exhaust gases are used for engine ice protection systems.
C. On turboprops the temperature of the exhaust gases can contribute to forward thrust, but on helicopters they serve no useful purpose.
D. It is not used at all, but rather it is lost to the atmosphere.
D. It is not used at all, but rather it is lost to the atmosphere.
Q. How is RPM typically measured in a turboshaft engine?
A. By utilising an AC generator, three phase independent electrical system and synchronous motor.
B. By measuring compressor outlet pressure, since compressor outlet pressure is proportional to engine RPM.
C. By utilising a sensor which measures fan blade passage over a pick-up.
D. By utilising an electronic counter which measures the ignition pulses.
A. By utilising an AC generator, three phase independent electrical system and synchronous motor.
Q. Turbine engine fuel systems commonly include a heat exchanger. One reason for this is to protect against:
A. the possibility of ice formation in the fuel.
B. absorption of atmospheric water vapour.
C. additives separating from the fuel.
D. overheating in the fuel lines.
A. the possibility of ice formation in the fuel.
Q. What would normally be the first indication of power loss on a turboprop engine?
A. A reduction in air intake temperature and pressure.
B. A reduction in torque and exhaust gas temperature.
C. A reduction in RPM and propeller disconnection from the turbine shaft.
D. An increase in exhaust gas temperature and a reduction in fuel flow.
B. A reduction in torque and exhaust gas temperature.
Q. Typically the lubrication systems of high bypass turbofan engines is _______ pressure _____ sump.
A. low dry
B. low wet
C. high wet
D. high dry
D. high dry
Q. What is the most positive indication of engine light-up during start?
A. A rise in exhaust gas temperature.
B. A stabilising of the engine RPM.
C. A rise in oil pressure.
D. A reduction in fuel flow.
A. A rise in exhaust gas temperature.
Q. The turbine temperature rising rapidly (unusually fast) towards the specified limit, is an indication of:
A. a wet start.
B. a hung (or false) start.
C. a hot start.
D. torching on start.
C. a hot start.
Q. How are turbine discs usually cooled?
A. By feeding a low pressure air supply from the exhaust through and onto the face of the disc.
B. By spraying oil onto the face of the disc.
C. By feeding a supply of high pressure air from the compressor onto the face of the disc.
D. By feeding bypass air into the hot gas stream beyond the combustion outlet.
C. By feeding a supply of high pressure air from the compressor onto the face of the disc.
Q. A combustion chamber’s liner and associated gas flow control and metering devices are designed to:
A. recirculate the air for repeat burning and to reduce CO emissions.
B. accelerate the gas flow and increase its pressure prior to the gases entry into the burning zone.
C. separate and control the gas flow for cooling and combustion and to create a region of low velocity recirculation of the air in the primary zone.
D. bleed off a portion of the gas flow for cooling of the turbine discs and sealing of the turbine shaft bearings.
C. separate and control the gas flow for cooling and combustion and to create a region of low velocity recirculation of the air in the primary zone.
Q. All other factors remaining the same, which of the following conditions will increase thrust or torque from a turbine engine?
A. An increase in density altitude.
B. An increase in air intake pressure.
C. An increase in air intake temperature.
D. A decrease in intake air density.
B. An increase in air intake pressure.
Q. What is the difference between a turboprop and a turboshaft?
A. With a turboprop the shaft is connected to a propeller gearbox, with a turboshaft the shaft is connected to something other than a propeller gearbox.
B. Turboprop engines are only fitted to fixed wing aircraft, while turboshaft engines are only fitted to helicopters.
C. There is no difference between turboprops and turboshafts, they are two names for the same type of engine.
D. With a turboprop the output from the engine is fed to the propeller through a gearbox, with a turboshaft the output shaft from the engine is connected directly to the propeller.
A. With a turboprop the shaft is connected to a propeller gearbox, with a turboshaft the shaft is connected to something other than a propeller gearbox.
Q. Which of the following best describes self sustaining RPM during start?
A. The RPM at which the starter has created a steady acceleration of the engine core.
B. The RPM at which the turbine is generating enough torque to accelerate on its own.
C. The RPM at which the engine has settled at ground idle.
D. The RPM at which the gas temperature starts to reduce.
B. The RPM at which the turbine is generating enough torque to accelerate on its own.
Q. For a gas at constant pressure, the temperature in a closed vessel will be directly proportional to its volume.
A. This is an expression of Boyle’s Law.
B. This is an expression of Charles’ Law.
C. This is an expression of Newton’s Second Law.
D. This is an expression of the first law of thermodynamics.
B. This is an expression of Charles’ Law.
Q. What percentage of normal forward thrust is normally achieved and used for reverse thrust, during reverse thrust operation?
A. About 10%.
B. Somewhat less than 50%.
C. 100%.
D. About 135%.
B. Somewhat less than 50%.
Q. 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?
A. A centrifugal compressor.
B. A centripetal compressor.
C. An axial flow compressor.
D. A radial compressor.
C. An axial flow compressor.
Q. How does the temperature, density, pressure and velocity of a gas flow vary through a convergent duct at supersonic speed?
A. Temperature, density, pressure and velocity all increase.
B. Temperature, density and pressure all increase, while velocity decreases.
C. Temperature, density and pressure all decrease, while velocity increases.
D. Temperature, density, pressure and velocity all decrease.
B. Temperature, density and pressure all increase, while velocity decreases.
Q. When talking about turbine blades, what is “creep”?
A. The changing of the turbine blade shape due to FOD ingestion.
B. The permanent lengthening of the turbine blade due to high temperatures and centrifugal reaction.
C. The lateral movement of turbine blades within their mounting on the disc.
D. The cyclic lengthening and subsequent shortening of turbine blades each time the engine is started and shutdown.
B. The permanent lengthening of the turbine blade due to high temperatures and centrifugal reaction.
Q. What is the cause of creep in turbine blades?
A. High temperatures and centrifugal reaction.
B. Poor blade design.
C. An imperfection in the blade construction.
D. An overspeed or overtemp of the engine.
A. High temperatures and centrifugal reaction.
Q. What acronym is used to describe the ratio of turbine outlet pressure to compressor inlet pressure?
A. TIT.
B. EPT.
C. EGT.
D. EPR.
D. EPR.
To determine EPR, pressure measurements are taken by probes installed in the engine inlet and at the turbine exhaust. The data from these sensors is sent to a differential pressure transducer which then indicates the ratio of the two pressures on a flight deck EPR gauge. EPR system design automatically compensates for the effects of airspeed and altitude.
Q. Exhaust gas temperature (EGT) indication systems operates by means of:
A. a number of thermocouples or pyrometers, arranged in series.
B. a combination of thermometers and thermocouples, arranged in series.
C. a combination of pyrometers and/or pyrocouples, arranged linearly.
D. a number of thermocouples, arranged in parallel.
D. a number of thermocouples, arranged in parallel.
Q. Why is Specific Gravity (SG) considered when loading AVTUR into an aircraft?
A. In order to calculate the temperature of the fuel to ensure fuel icing does not become a problem later in flight.
B. Because the cost of fuel is determined by its SG, and airline accounting departments require this information for invoice reconciliation.
C. Because AVTUR is more susceptible to SG changes than other fuels, with a consequent change in its volatility.
D. Because fuel is loaded from the ground facility by volume (gallons or litres) and to convert volume to weight/mass (pound or kilograms) its SG is needed.
D. Because fuel is loaded from the ground facility by volume (gallons or litres) and to convert volume to weight/mass (pound or kilograms) its SG is needed.
Q. What are the primary functions of air seals in a turbine engine?
A. To pressurise the compressor rotor area and cool hot section areas.
B. To pressurise labyrinth and carbon seals and cool hot section areas.
C. To prevent ram air from escaping from the air inlet system.
D. To prevent turbine outlet gas flow escaping through the nozzle system.
B. To pressurise labyrinth and carbon seals and cool hot section areas.
Q. What is the primary function of the nozzle diaphragm?
A. To prevent choking of the heated gases flowing past this particular point, thereby reducing the possibility of turbine and compressor stall.
B. To increase the pressure of the exhaust gases.
C. To maximise the velocity of the gas exiting the combustion section ,and to direct the gases at the optimum angle onto the turbine blades.
D. To decrease the velocity of heated gases flowing past this particular point.
C. To maximise the velocity of the gas exiting the combustion section ,and to direct the gases at the optimum angle onto the turbine blades.
Q. With respect to the combustion process, how do turbine engines differ from reciprocating (piston) engines?
A. In turbine engines combustion takes place at near constant velocity, while in a reciprocating engine combustion takes place at an increasing temperature.
B. In turbine engines combustion takes place at near constant pressure, while in a reciprocating engine combustion takes place at a constant volume.
C. In turbine engines combustion takes place at near constant temperature, while in a reciprocating engine combustion takes place at a increasing pressure.
D. In turbine engines combustion takes place at near constant volume, while in a reciprocating engine combustion takes place at an increasing pressure.
B. In turbine engines combustion takes place at near constant pressure, while in a reciprocating engine combustion takes place at a constant volume.
Q. What is the ideal air/fuel ratio for combustion in a turbine engine?
A. 10:1
B. 15:1
C. 20:1
D. 30:1
B. 15:1
Q. Blocker doors moving to blank off the bypass fan air exit and redirect it forward on a high bypass turbofan, describes:
A. blade reversers.
B. clamshell reversers.
C. bucket reversers.
D. cold-stream reversers.
D. cold-stream reversers.
Q. Which instrument(s) indicate the thrust output of a turboprop engine?
A. Fuel flow.
B. Turbine temperature.
C. EPR.
D. Engine torque and RPM.
D. Engine torque and RPM.
Q. Equivalent horsepower is:
A. the power delivered to a helicopter main rotor gearbox on a turboshaft engine.
B. shaft horsepower plus the effect of residual jet thrust on a turboprop engine.
C. the power delivered to the propeller on a turboprop engine.
D. brake horsepower corrected for density changes.
B. shaft horsepower plus the effect of residual jet thrust on a turboprop engine.
Q. What would normally be the first indication of power loss on a turboprop engine?
A. A reduction in air intake temperature and pressure.
B. A reduction in torque and exhaust gas temperature.
C. An increase in exhaust gas temperature and a reduction in fuel flow.
D. A reduction in RPM and propeller disconnection from the turbine shaft.
B. A reduction in torque and exhaust gas temperature.
Which type of compressor can be described as short in length, spoke like in design, relatively simple to manufacture, with high compression per stage?
A. An axial flow compressor.
B. A turbine compressor.
C. A centrifugal compressor.
D. A centripetal compressor.
C. A centrifugal compressor.
Q. For a gas at constant pressure, the temperature in a closed vessel will be directly proportional to its volume. This is an expression of:
A. Boyle’s Law.
B. Charles’ Law.
C. the first law of thermodynamics.
D. Newton’s First Law.
B. Charles’ Law.
Q. Which instrument(s) indicate the thrust output of a turbofan engine?
A. EPR and/or N1.
B. Engine torque.
C. Turbine temperature.
D. Fuel flow
A. EPR and/or N1.
Q. 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:
A. Charles’ Law.
B. Newton’s Fourth Law.
C. Boyle’s Law.
D. the second law of thermodynamics.
C. Boyle’s Law.
Q. Which of the gas flows from a turbofan engine is used to generate reverse thrust?
A. Compressor flow by reversing the angle of the fan blades.
B. Combustion gases from reverse flow engines.
C. The hot exhaust gas from the core flow.
D. The cold stream flow from the bypass duct.
D. The cold stream flow from the bypass duct.
Q. In which one of the following ways does AVTUR differ from AVGAS?
A. AVTUR has a higher calorific value.
B. AVGAS has better self lubricating properties.
C. AVGAS has a higher specific gravity.
D. AVTUR is more volatile.
A. AVTUR has a higher calorific value.
Q. What check does a refueller perform to ensure that only acceptable levels of water are present in your Jet A1?
A. A visual check of a sample of the fuel delivered.
B. A chemical check involving a colour change if excess water is present.
C. A visual check of the sophisticated filter system.
D. Water content is continuously electronically monitored and an alarm will sound if excess water is present.
B. A chemical check involving a colour change if excess water is present.
Q. How is a demand by the pilot for more thrust handled mechanically in a turbine engine?
A. The power lever is connected to a fuel control unit which senses compressor inlet temperature, exhaust gas temperature, compressor outlet pressure and engine RPM.
B. The power lever is connected to the fuel pump which provides more fuel pressure. This is sensed by the fuel nozzle sensors which inject more fuel into the combustion chamber.
C. The power lever is connected to a fuel control unit which contains a governor to maintain RPM.
D. The power lever is connected to the fuel nozzle apparatus which allows more fuel into the burner.
A. The power lever is connected to a fuel control unit which senses compressor inlet temperature, exhaust gas temperature, compressor outlet pressure and engine RPM.
Q. Turbine blades used in modern turbine engines are generally:
A. Impulse-impulse type.
B. reaction type.
C. impulse type.
D. impulse-reaction type.
D. impulse-reaction type.
Q. What is the name of the rotating component of a centrifugal compressor that takes inlet air in at its centre and compresses it by centrifugal force? A. A turbine. B. A stator. C. A radiator. D. An impeller.
D. An impeller.
Q. Which instrument(s) indicate the thrust output of a turbofan engine? A. EPR and/or N1. B. Turbine temperature. C. Engine torque. D. Fuel flow
A. EPR and/or N1.
Q. The shape of the intake duct on a turbofan engine is: A. fractious. B. convergent. C. constant diameter. D. divergent.
D. divergent.
Q. How do bucket reversers function? A. By blocker doors in the bypass duct moving to blank off the cold fan air redirecting it forward. B. By blocker doors inside the exhaust duct moving to blank off the hot exhaust gases redirecting them forward. C. By blocker doors external to the exhaust duct moving to blank off the hot exhaust gases redirecting them forward. D. By cascade vanes in the nacelle surrounding the bypass duct opening to allow the cold fan air to flow outward and forward.
C. By blocker doors external to the exhaust duct moving to blank off the hot exhaust gases redirecting them forward.
Q, How do clamshell reversers function? A. By blocker doors inside the exhaust duct moving to blank off the hot exhaust gases redirecting them forward. B. By blocker doors in the bypass duct moving to blank off the cold fan air redirecting it forward. C. By cascade vanes in the nacelle surrounding the bypass duct opening to allow the cold fan air to flow outward and forward. D. By blocker doors external to the exhaust duct moving to blank off the hot exhaust gases redirecting them forward.
A. By blocker doors inside the exhaust duct moving to blank off the hot exhaust gases redirecting them forward.
