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24 Cards in this Set
- Front
- Back
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Explain the main difference and advantage of turbofan over turbojet engines,.
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A turbofan engine uses a fan to bypass some air around the engine core to provide thrust. The advantage is that this provides additional thrust without increasing fuel flow.
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Name the major components in a gas turbine engine.
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Air inlet,compresor , combustion , turbine, exhaust ,gearbox and accessory section
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What determines the amount of airflow through a turbine engine?
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The forward speed of the aircraft, compressor speed, an air density
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Name the two types of compressors commonly used in turbine engines.
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Axial and centrifugal flow compressors.
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Name two different methods for attaching turbine engine rotor blades to the rotor disk.
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Doventail type root Bulb type root Fir tree type root |
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What is a split compressor system?
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Also called dual or twin spool compressors, these are connected to the turbine section with two rotor shafts, one inside the other
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What are the different types of combustion chambers used in a turbine engine? |
Can, annualar, can annular and reverser flow annular |
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What prevents the combustion chambers from burning?
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Cooling air along the inside of the liner.
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What is the purpose on the interconnecting tubes attached between can type combustion chamber?
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For flame propagation during start. |
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What functions do axial flow turbine nozzle perform?
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They direct the mass airflow to drive the turbine rotor at a specific angle.
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How is thermal stress relieved on a turbine disc?
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By directing bleed air onto the face of the disk, or by groves being cut on the disk.
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What are carbon seals used for in a turbine engine?
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They are used as oil seals for the rotor shaft bearings.
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What is shaft horsepower?
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It is an indication of the torque developed by a turboprop or turboshaft engine.
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What is the purpose of an APU? |
They provide ground electrical and pneumatic for aircraft systems when the engines are not running. Pneumatic power can be used for engine starting , ground heating or air conditioning , and anti-icing. Many APUs may also be used as an emergency source of inflight electrical power. |
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Name the main components of a typical APU?
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A small power turbine for power and bleed air, and electrical generator.
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When is the greatest demand placed on an APU?
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When supplying bleed air.
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How is an APU generally started?
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With its own electrical starter and battery power. |
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Where does the APU get its fuel supply?
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One of the Aircraft main fuel tanks.
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At what speed does a gas turbine APU operate and how is this speed maintained?
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At or near its rated speed regardless of electrical or pneumatic loads imposed. The APU fuel control automatically adjust the fuel flow to maintain the rated speed.
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What is used to prevent a heavily loaded APU from exceeding its maximum EGT?
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A load control valve modulates the pneumatic load to maintain EGTs with in limits.
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How is an APU shut down and why is this procedure used?
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After the APU is unloaded by closing the bleed air valve , it is run for a specific amount of time to allow the EGT to cool and stabilize. This cool down period is typically 3 minutes. If a heavily loaded APU is abrupt shut down with out any cool down period, damage could occur as a result of thermal shock.
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What powers the variable inlet guide vanes used on some APUs to regulate compressor intake airflow?
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Fuel Pressure
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What is fan blade shingling?
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It is the overlapping of the midspan shrouds of the fan turbine. |
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When a turbofan or turbojet engine is shut down, what should a mechanic listen for during coast down?
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Any rubbing sound or other unusual noises from engine.
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