Exam 1 Flashcards
Turbine fuel with a civilian classification Jet A1 is known as \_\_ in the United States and has the military classification \_\_. A JP-5 F-35 B JP-8 F-80 C JP-40 F-45 D JP-4 F-40
A
Why is Specific Gravity (SG) considered when loading AVTUR into an aircraft?
A Because the cost of fuel is determined by its SG, and airline accounting departments require this information for invoice reconciliation.
B Because AVTUR is more susceptible to SG changes than other fuels, with a consequent change in its volatility.
C 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 In order to calculate the temperature of the fuel to ensure fuel icing does not become a problem later in flight.
C.
How does the temperature, density, pressure and velocity of a gas flow vary through a divergent duct at supersonic speed?
A Temperature, density and pressure both decrease, while velocity increases.
B Temperature, density, pressure and velocity all increase.
C Temperature, density, pressure and velocity all decrease.
D Temperature and pressure both increase, while velocity and density decreases.
A.
In what ways are turbine engines and reciprocating (piston) engines similar?
A Both types of engine use the same lubricating oil.
B Both types of engine are internal combustion.
C Both types of engine use the same fuel.
D Both types of engine have the same power to weight ratio.
B.
How do clamshell reversers function?
A By blocker doors external to 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 blocker doors inside 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.
There are three general types of combustion chamber. The most easily serviced is totally external to the engine, the second is a dual ring system and the third is an efficient combination of the two others. Which of the following lists the three types, in the order described? A Can, Can-annular and Annular. B Can, Annular and Can-annular. C Can-annular, Annular and Can. D Can-annular, Can and Annular.
.B
In which one of the following ways does AVTUR differ from AVGAS?
A AVGAS has better self lubricating properties.
B AVTUR has a higher calorific value.
C AVTUR is more volatile.
D AVGAS has a higher specific gravity.
B.
Turbine blades used in modern turbine engines are generally: A fir leaf. B impulse. C impulse-reaction. D reaction.
C.
The primary function of a turbine engine’s lubrication system is to:
A clean metal particles from the turbine shaft bearings.
B protect the turbine blades from corrosion.
C cool the internal bearings.
D prevent metal to metal contact.
D.
With respect to the mechanical efficiency, how do turbine engines differ from reciprocating (piston) engines?
A The reciprocating engine is more mechanically efficient.
B The respective mechanical efficiency of the two engine types depends on the prevailing operating environment.
C There is no difference between the two engine types with respect to mechanical efficiency.
D The turbine engine is more mechanically efficient.
D.
Which of the gas flows from a turbofan engine is used to generate reverse thrust?
A The hot exhaust gas from the core flow.
B The cold stream flow from the bypass duct.
C Compressor flow by reversing the angle of the fan blades.
D Combustion gases from reverse flow engines.
B.
What acronym is used to describe the ratio of turbine outlet pressure to compressor inlet pressure? A EGT. B TIT. C EPT. D EPR.
D.
What is the name given to the permanent lengthening (elongation) of turbine blades? A Stretch. B Creep. C Rubbing. D Distension.
B.
How is the residual temperature of the exhaust gases utilised?
A On turboprops the temperature of the exhaust gases can contribute to forward thrust, but on helicopters they serve no useful purpose.
B Exhaust gases are used for engine ice protection systems.
C Exhaust gases are used for airframe ice protection systems.
D It is not used at all, but rather it is lost to the atmosphere.
D.
A similarity between turbine and reciprocating engines is that:
A both engines have a continuous gas flow.
B both engines use the same type of fuel.
C both engines use the same type of lubricating oil.
D both are internal combustion engines.
D.
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 temperature. C A decrease in intake air density. D An increase in air intake pressure.
D.
How is RPM typically measured in a turboshaft engine?
A By utilising a sensor which measures fan blade passage over a pick-up.
B By utilising an AC generator, three phase independent electrical system and synchronous motor.
C By utilising an electronic counter which measures the ignition pulses.
D By measuring compressor outlet pressure, since compressor outlet pressure is proportional to engine RPM.
B.
Typically the lubrication systems of high bypass turbofan engines is \_\_\_\_\_\_\_ pressure \_\_\_\_\_ sump. A low wet B low dry C high wet D high dry
D.
Which of the following is an advantage of an axial flow compressor, compared to a centrifugal compressor?
A An axial flow compressor is more resistant to FOD.
B An axial flow compressor is less prone to compressor stall/surge.
C An axial flow compressor allows for a smaller engine diameter for a given mass flow capacity.
D An axial flow compressor is more robust and easier to manufacture.
C.
Which of the following statements regarding Specific Fuel Consumption (SFC) is correct?
A SFC is a measure of engine efficiency. When SFC is high, engine efficiency and therefore fuel economy is high.
B SFC decreases if the compressor is dirty or damaged.
C SFC is a measure of engine efficiency. When SFC is low, engine efficiency and therefore fuel economy is high.
D SFC increases with altitude, since RPM is increased to maintain a given thrust.
C.
In a turbine engine, which of the following is an advantage applicable to an axial flow compressor when compared to a centrifugal compressor?
A It can achieve higher compression ratios more efficiently.
B It is better able to handle foreign object ingestion.
C It is not as prone to stalling and surging.
D It is more robust and easier to manufacture.
A.
Which of the following best describes self sustaining RPM during start?
A The RPM at which the engine has settled at ground idle.
B The RPM at which the turbine is generating enough torque to accelerate on its own.
C The RPM at which the starter has created a steady acceleration of the engine core.
D The RPM at which the gas temperature starts to reduce.
B.
The source of bleed air in a turbine engine is normally from the: A turbine. B combustion chamber. C exhaust. D compressor.
D.
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.
How are modern turbine blades cooled in a turbofan engine?
A Secondary combustion air is blown over and through them.
B Oil is splashed over them.
C Bleed air from the compressor is blown over and/or through them.
D Fan air is blown over and through them.
C.
What does the term reverse flow mean when used to describe the combustion section of a turbine engine?
A Reverse flow means that combustion gases are directed through a cooling section so that the fan can be mounted externally at the rear of the engine.
B Reverse flow means that raw fuel is injected into the combustion gases for reheat (after burning).
C Reverse flow means that the gas reverses its direction during the combustion process.
D Reverse flow means that the combustion gases are vectored forward to aid deceleration during landing or on a rejected takeoff.
C.
What are the two main types of intake on turbofan engined aircraft? A Centreline and offset. B Shielded and unshielded. C Divided and pitot. D Convergent and divergent.
C.
Multiple, separate interconnected chambers within a common air casing, encircling the turbine shaft, describes: A an annular combustion chamber. B can-annular combustion chamber. C a can combustion chamber. D axial flow combustion chamber.
B.
Which of the following additives are commonly used in Jet A1? A Anti-microbiocodal. B Anti-inflammatory. C Anti-serum. D Anti-toxin.
A.
How does the pressure, temperature and velocity change across a stage of an axial compressor?
A Pressure, temperature and velocity all decreases across both the rotor and the stator.
B Pressure, temperature and velocity all increases across both the rotor and the stator.
C Pressure and temperature both decrease across both the rotor and the stator, while velocity increases across the stator and decreases across the rotor.
D Pressure and temperature both increase across both the rotor and the stator, while velocity decreases across the stator and increases across the rotor.
D.
