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avi145
turbine engines
180
Aviation
Undergraduate 1
02/25/2015

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Term
Newton's first law of motion
Definition
A body at rest tends to remain at rest and a body in motion tends to continue in motion in a straight line unless caused to change its state by an external force
Term
Newton's second law of motion
Definition
The acceleration of a body is directly proportional to the force causing it and inversely proportional to the mass of the body
Term
Newton's third law of motion
Definition
For every action, there is an equal and opposite reaction
Term
Energy transformation cycle of a gas Turbin engine
Definition
Intake
compression
combustion
exhaust
Term
What is thrust
Definition
A reaction force measured in pounds
Action= acceleration of air mass
Reaction= Forward movement
Term
Bernoulli's principle
Definition
Velocity increase = pressure decrease
Velocity decrease = pressure increase
Term
Factors affecting thrust
Definition
Temperature.
Humidity.
Altitude.
Airspeed.
Engine rpm.
Fan efficiency.
Water injection.
Afterburner
Term
Standard day
Definition
0 ft altitude
59°F
29.92 in/hg (mercury)
Term
Four types of gas turbine engines
Definition
Turbojet
Turbofan
Turboprop
Turboshaft
Term
Fuel heater
Definition
Heat exchanger- Engine oil or Bleed air
Fuel flows continuously
Term
Simplex nozzle
Definition
Provides single spray pattern
Term
Duplex nozzle
Definition
2 independent discharge orfices,
(small & large)
Small orifice = Center- Primary fuel (idle)
Large orifice = around center- Secondary fuel
Can be single or dual line
Term
P&D valve
Definition
Pressurization and Dump Valve
Usually used in fuel systems with dual line duplex nozzles
-pressurize fuel in primary and secondary manifolds
-empty or dump all of the fuel in the 2 manifolds upon engine shutdown
Term
What is the Brayton cycle?
Definition
Simultaneous / continuous intake, compulsion and compression at constant pressure
Term
The function of the turbine in a turbojet is to drive the ______
Definition
Compressor blades
Term
Determine engine that uses a separate turbine to drive a reduction gearbox, and / or propeller is a ________ engine
Definition
Free turbine
Term
What are three and villages of a turbofan over a turbojet engine
Definition
More efficient / less fuel
Fan will divert FOD
Quieter
High thrust at low speeds
Term
The ratio of the amount of air that passes through the fan to that which flows through the core of the engine is called ________
Definition
Bypass ratio
Term
Convergent subsonic air flow
Definition
Velocity increases
Pressure decreases
Term
Divergent subsonic air flow
Definition
Pressure increases
Velocity decreases
Term
Convergent supersonic air flow
Definition
Velocity decreases
Pressure increases
Density increases
Term
Divergent supersonic air flow
Definition
Velocity increases
Pressure decreases
Density decreases
Term
What is the cold section consist of
Definition
Inlet
Compressor
Diffuser
Term
What speed must the air entering the engine be?
Definition
Subsonic
Term
what are the two sections into which a gas turbine engine can be divided?
Definition
Hot
Cold
Term
Can let ducts are part of ________
Definition
The airframe
Term
Name two classifications of inlet ducts
Definition
Supersonic
Subsonic
Term
What is a stall
Definition
When an airfoil exceed its critical angle of attack
Term
What is the use of inlet guide vanes
Definition
-Slightly reduces the amount of air flowing through the engine (to prevent compressor stall)
-Direct air to the first stage of the compressor at the proper angle.
-Used on axial flow turbine engines
Term
Two types of compressors with respect to air flow
Definition
Centrifugal type.
Axial type
Term
Three types of compressors with respect to performance
Definition
Single stage.
Two Stage.
Multiple stage.
Term
What is a compressor stall?
Definition
Occurs when the compressor blades angle of attack exceed the critical angle of attack, at this point smooth air flow is interrupted and turbulence is created with pressure fluctuations
Term
What a profile tip
Definition
Reduced blade thickness at tip
Term
Three types of rotor blade roots
Definition
Bulb
Fir tree
Dovetail
Term
What is compressor air supplied for
Definition
Cabin pressurization.
Kevin heating.
Cabin cooling.
Cooling turbine inlet guide vanes
Cooling turbine wheel.
Deicing systems.
Anti-icing systems.
Pneumatic engine starting
Term
Where is the diffuser located?
Definition
Between the compressor and combustion chamber
Term
What the diffuser do?
Definition
Produces electricity and increases pressure
Divergent shape
Point of highest pressure in the engine
Term
Pressure of air passing through the compressor is a measure of _____ energy
Definition
Potential
Term
Air taken from the compressor to anti-ice the inlet duct is known as ______ air
Definition
Bleed
Term
What are other uses for bleed air?
Definition
Cooling
Pressurize cabin
A.c.
Term
Name two types of compressors used on turbine engines
Definition
Axial
Centrifugal
Term
Name the three components of a centrifugal compressor
Definition
Impeller
Diffuser
Compressor manifold
Term
Name the components of an axial flow compressor
Definition
Stators
Rotors
Term
A compressor blade with a tip having a decreased thickness is known as _______
Definition
Profile
Term
Two design features that may be used to prevent or minimize compressor stalls are
Definition
Bleed air
VIGV (or VSV)
Term
Two variables that affect compressor stall are
Definition
RPM
velocity of airflow
Through compression
Term
What is the Hot Section consist of?
Definition
Combustion section
turbine section
exhaust section
Term
Located directly behind the diffuser=
Where the fuel & air is mixed & burned=
Definition
Combustion section
Term
What does the combustion section consist of?
Definition
One or more combustion chambers
a fuel injection system
an ignition system
an ignition source
a fuel drianage system
Term
ATA 72
Definition
Engine
Term
ATA 71
Definition
Powerplant
Term
ATA 83
Definition
Accessory Gearbox
Term
ATA 12
Definition
Servicing
Term
ATA 73
Definition
Fuel and Control
Term
What is a LRU?
Definition
Line Replaceable Unit
Term
Name 4 LRU's that could be found attached to a turbine engine gearbox.
Definition
Hydraulic pump
Generators
Oil pump
Starter
Fuel Control Unit (FCU)
Boost pump
Fuel Pump
Oil cooler
Term
In addition to powering aircraft accessories, what other secondary function does the gearbox serve?
Definition
Oil sump
Lubrication
Term
On a dual spool turbofan, which rotor drives the accessory gearbox?
Definition
N2
Term
What are 2 types of fuels used for turbine engines?
Definition
Jet A
Jet B
Term
what is the difference of the 2 turbine fuels?
Definition
Jet A= primarily kerosene
Jet B= 70% gasoline, 30% kerosene
Term
Name the 3 types of turbine engine fuel nozzles.
Definition
Simplex
Duplex
Vaporizing
Term
What are the 2 functions of the P&D valve?
Definition
Divide flow
Dump
Term
[image]
Definition
1. Tank
2. Boost pump
3. Shut Off Valve (SOV)
4. Fuel Pump
5. Low Pressure Pump
6. Fuel Heater
7. Bypass
8. High Pressure Pump
9. Bypass
10. SOV (air)
11. Filter
12. Differential pressure switch
13. Bypass
14. Fuel Control
15. Fuel flow transmitter
16. oil cooler
17. P&D valve
18. Primary
19. Secondary
20. Nozzle
21. Fuel dump
Term
[image]
Definition
Convergent Duct=
Velocity = Decreases
Pressure = Increases
Density = Increases

Divergent Duct=
Velocity = Increases
Pressure = Decreases
Density = Decreases
Term
[image]
Definition
Convergent Duct=
Velocity = Increases
Pressure = Decreases

Divergent Duct=
Velocity = Decreases
Pressure = Increases
Term
An increase in airspeed will cause a turbojet engine's thrust to ______
Definition
Decrease
Term
Pt2 refers to ______
Definition
Total pressure at station 2
Term
Ducts in the diffuser of a turbine engine are _________ in shape.
Definition
Divergent
Term
What are two types of turbine engine compressors?
Definition
Axial
Centrifugal
Term
In turbine engine, the air that is used for combustion is known as __________
Definition
Primary Air
Term
What is the most common type of turbine blade (shape) used on modern turbine engines?
Definition
Impulse-Reaction
Term
Between each row of rotating blades in a turbine engine compressor, there is a row of stationary blades which act to diffuse the air. these stationary blades are called __________
Definition
Stators
Term
What is the primary factor which controls the pressure ratio of an axial-flow compressor?
Definition
Number of Stages
Term
Name 3 types of combustion sections used in aircraft turbine engines.
Definition
Can
Anular
Can-Anular
Term
On an aircraft turbine engine, operating at a constant power, the application of engine anti-icing will result in ______________
Definition
Lower Thrust
Higher Temperature
Term
Name 4 main factors that affect thrust
Definition
Temperature
Altitude
Air density
RPM
Air Speed
Fan Efficiency
Afterburner
Term
What is the purpose of a bell mouth inlet?
Definition
To allow smooth airflow into the engine at low speeds
Term
What are 4 uses for bleed air from a turbine engine?
Definition
Cabin Pressurization
Cabin Heating
Cabin Cooling
Cooling turbine inlet guide vanes
Cooling turbine wheel
Deicing systems
Anti-icing systems
Pneumatic engine starting
Term
ATA 79
Definition
Lubrication
Term
ATA 11
Definition
Required Placards
Term
Name 2 types of Turbine engine oils.
Definition
Type I
Type II
Term
What type of oil system is typically found on turbine engines?
Definition
Dry Sump
Term
Why do turbine engine manufacturers recommend servicing oil after engine shut down?
Definition
Prevent over servicing
Term
Name 3 types of positive displacement pumps used for fuel or oil systems.
Definition
Gear
Vane
Gerotor
Scavange
Term
What is the purpose of the thermostatic valve in a turbine engine cooler?
Definition
controls the amount of oil that flows to the cooler
Oil cold – bypass valve open – oil will bypass the cooler
Oil hot – bypass valve closed – oil will flow through the cooler
Term
According to Federal Aviation Regulations, oil tank fillers on turbine engines must be marked with _________
Definition
"Oil"
Term
Describe the operation of an indicating chip detector.
Definition
metal chips in oil are trapped. when build up or large enough chips are captured they bridge a gap in the mesh filter completing an electrical circuit and an indicating light is illuminated
Term
Name 2 types of oil seals used on a turbine engine.
Definition
Labyrinth
Helical
Carbon
Term
What is the primary purpose of the fuel to oil heat exchanger?
Definition
To Cool Oil
(oil cooler)
Term
What are 2 things that will happen if the oil filter becomes blocked?
Definition
lights up warning light
bypass valve opens (bypassing filter completely)
Term
What is a Hot Tank oil system?
Definition
Oil is cooled after leaving tank (oil is hot in tank)
Term
What is the purpose of the dwell chamber of a turbine engine oil tank?
Definition
chamber where oil is temporarily stored to help eliminate bubbles and foam
Term
What color are turbine engine fuels?
Definition
Straw
Term
What is PRIST? What is it's purpose? How does it work?
Definition
Fuel additive
-Prevents ice and bacterial contamination
--As the fuel temperature decreases, the additive combines with the water in greater concentrations. This combination will keep the freezing point of the water lower than the temperature of the fuel.
Term
Describe the operation of a cooled oil cooler/fuel heater.
Definition
Heat Exchanger–Engine Oil or Bleed Air.
Fuel flows through continuously.
Activated manually or automatically.
Term
What is the airflow through the combustor divided into?
Definition
Primary
Secondary
Term
Explain the Primary path of airflow through the combustor.
Definition
25% to 35% of incoming air.
Passes through a set of swirl vanes, gives air a radial motion & slows velocity.
Term
Explain the Secondary path of airflow through the combustor.
Definition
65% to 75% of incoming air
Secondary air for cooling
Term
What are the types of combustion chambers?
Definition
Can type/ Multiple-can type
Annular or Basket type
Can Annular type
Term
What are the 4 basic parts of the Turbine section?
Definition
Case
Stator
Shroud
Rotor
Term
What are the other names for the turbine Stators?
Definition
Turbine nozzle
Turbine Guide Vane
Turbine nozzle Diaphragm
Term
What is the part with the hottest heat to metal temperature in a turbine engine?
Definition
Turbine Nozzle
Term
What does the turbine rotor consist of?
Definition
Shaft
Turbine rotor or wheel
Term
What is the shape of Turbine Blades? Why?
Definition
Airfoil shaped
Designed to extract the maximum amount of energy from the flow of hot gases
Term
What is the most common Turbine Blade attachment shape?
Definition
Fir Tree
Term
What are the classifications of Turbine Blades?
Definition
Impulse Type
Reaction Type
Impulse-Reaction Type
Term
What is the accessory gearbox powered by?
Definition
Engine's main power shaft
Term
ATA 77
Definition
Engine indicating
Term
ATA 74
Definition
Ignition
Term
What are the ignition system Components?
Definition
Transformer/ exciter box (2)
Ignition Lead (2)
Igniter (2)
Term
Basic parts of a Igniter
Definition
Shell/Body
Insulator
Internal seals
Electode
Term
2 types of Igniters
Definition
Low voltage
High voltage
Term
Types of starters
Definition
Starter-Generators
Combustion Starters
Gas turbine type
Cartridge type
Air Turbine
Direct Cranking Starter
Term
Engine Instrumentation
Definition
Compressor speed
Engine Pressure Ratio
Turbine discharge pressure
Torquemeter
Fuel Flow indicator
Oil pressure gage
Oil teperature gage
Exhaust gas temperature - EGT
Engine Indicating & Crew Alerting System (EICAS)
Term
How is Compressor speed monitored?
Definition
-Tachometer in % RPM
-Separate Tach for each compressor
Term
what is the engine pressure ratio? what does the EPR gauge indicate?
Definition
Ratio of Turbine Discharge Pressure to Compressor Inlet Pressure
Indicates amount of thrust produced.
Pressure taken at Pt2 & Pt7
Term
Turbine engine Starting Safety check
Definition
Master Switch – OFF
Battery Switch – OFF
Landing Gear Handle – DOWN
Generator Switches – OFF
Starter Switch – OFF
Ignition Switch – Off (Circuit Breaker IN)
Power Lever - Cutoff
Term
Turbine engine starting Pre-Start Checks
Definition
Ground Power – Verify correct voltage & air pressure.
Master Switch – ON
Battery Switch – ON
External Power Switch – ON
Fuel Boost Pump(s) – ON
Fuel Valve(s) Selected – OPEN
Low Fuel Pressure Light – OFF
Term
Starting a Turbine Engine
Definition
Start Switch – Start
-Watch RPM indicator
25% RPM – Power Lever to IDLE Position
-Watch for Fuel Flow
-Watch EGT gage
-Watch oil pressure gage
Term
What is a hot start?
Definition
If EGT exceeds allowable limits
(SHUT OFF FUEL IMMEDIATELY)
Term
What is a Hung Start?
Definition
Engine Fails to accelerate or reach idle RPM
(shut down immediately)
Term
What do you do if a fire starts in the engine during start cycle?
Definition
Cut off fuel
Continue motoring engine with the starter
Term
Engine shutdown procedure...
Definition
Engine checks complete
Run engine at idle for 30 – 60 seconds
Power Lever – Cutoff
Fuel Valve(s) Selected – Closed
Fuel Boost Pump(s) – OFF
External Power Switch – OFF
Battery Switch – OFF
Master Switch - OFF
Term
Primary Uses of an APU
Definition
To drive an electric generator
Supplies bleed air for heating, cooling, anti-ice, and engine starting
Term
ATA 76
Definition
engine control
Term
ATA 80
Definition
Starting
Term
ATA 49
Definition
APU
Term
ATA 70
Definition
Standard practices
Term
ATA 4
Definition
Airworthiness limitations
Term
ATA 5
Definition
Time limitations
Term
subsonic planes have what type of exhaust cone?
Definition
Convergant
Term
Any type of maintenance that can be done while the engine is installed on the aircraft.
Definition
Line Maintenance
Term
Maintenance the requires the engine to be taken off the aircraft. (normally performed at an overhaul facility)
Definition
Shop Maintenance / Heavy Maintenance
Term
Adjust fuel control for maximum rated thrust
Definition
Trimming
Term
powerplant components
Definition
Fan and booster
High pressure compressor
Combustor
High pressure turbine
Low pressure turbine
Accessory drive
Term
ATA 76
Definition
engine control
Term
ATA 80
Definition
Starting
Term
ATA 49
Definition
APU
Term
ATA 70
Definition
Standard practices
Term
ATA 4
Definition
Airworthiness limitations
Term
ATA 5
Definition
Time limitations
Term
subsonic planes have what type of exhaust cone?
Definition
Convergant
Term
Any type of maintenance that can be done while the engine is installed on the aircraft.
Definition
Line Maintenance
Term
Maintenance the requires the engine to be taken off the aircraft. (normally performed at an overhaul facility)
Definition
Shop Maintenance / Heavy Maintenance
Term
Adjust fuel control for maximum rated thrust
Definition
Trimming
Term
powerplant components
Definition
Fan and booster
High pressure compressor
Combustor
High pressure turbine
Low pressure turbine
Accessory drive
Term
ATA 76
Definition
engine control
Term
ATA 80
Definition
Starting
Term
ATA 49
Definition
APU
Term
ATA 70
Definition
Standard practices
Term
ATA 4
Definition
Airworthiness limitations
Term
ATA 5
Definition
Time limitations
Term
subsonic planes have what type of exhaust cone?
Definition
Convergant
Term
Any type of maintenance that can be done while the engine is installed on the aircraft.
Definition
Line Maintenance
Term
Maintenance the requires the engine to be taken off the aircraft. (normally performed at an overhaul facility)
Definition
Shop Maintenance / Heavy Maintenance
Term
Adjust fuel control for maximum rated thrust
Definition
Trimming
Term
powerplant components
Definition
Fan and booster
High pressure compressor
Combustor
High pressure turbine
Low pressure turbine
Accessory drive
Term
ATA 76
Definition
engine control
Term
ATA 80
Definition
Starting
Term
ATA 49
Definition
APU
Term
ATA 70
Definition
Standard practices
Term
ATA 4
Definition
Airworthiness limitations
Term
ATA 5
Definition
Time limitations
Term
subsonic planes have what type of exhaust cone?
Definition
Convergant
Term
Any type of maintenance that can be done while the engine is installed on the aircraft.
Definition
Line Maintenance
Term
Maintenance the requires the engine to be taken off the aircraft. (normally performed at an overhaul facility)
Definition
Shop Maintenance / Heavy Maintenance
Term
Adjust fuel control for maximum rated thrust
Definition
Trimming
Term
powerplant components
Definition
Fan and booster
High pressure compressor
Combustor
High pressure turbine
Low pressure turbine
Accessory drive
Term
A sever condition of chafing or fretting in which a transfer of metal from one part to another occurs is called...
Definition
Galling
Term
What must be done after the fuel control unit has been replaced on an aircraft gas turbine engine?
Definition
Engine Trim
Term
Why is a cool-off period necessary prior to shutdown of a turbine engine?
Definition
So the case does not shrink around blades
So cracking does not occur
Term
What is the purpose of an under-current relay in a starter-generator system?
Definition
Determines that a starter is spinning fast enough to shut itself off
Term
What is the primary advantage of pneumatic (air-turbine) starters over comparable electric starters for turbine engines?
Definition
Power-to-weight ratio
Term
Describe the basic procedure for removing a turbine engine ignition system.
Definition
Turn power off
Pull circuit breaker
remove leads
Wait to discharge
remove
Term
Describe the basic start procedure for a typical turbine engine.
Definition
starter
ignition
add fuel last
Term
How is an APU cooled down prior to shutdown?
Definition
turn off bleed air loads and electricity
Term
(T/F)
When an aircraft has an APU on board, an engine-mounted starter is required
Definition
True
Term
(T/F)
Propeller RPM is the primary indication of thrust for a turboprop engine
Definition
False
(Torque)
Term
(T/F)
EGT is a useful indication of thrust produced in a turbine engine
Definition
False
(used for temperature)
Term
What are the factors that can cause a hung start?
Definition
improper fuel control
problem with starter
starter doesn't crank long enough
battery dies
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