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Aviation machinist mate
CORE 1 study guide
258
Aviation
Professional
06/10/2013

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Term
Matter
Definition
Anything that occupies space
Term
What are the 3 states of matter?
Definition
Solid, liquid, gas
Term
Solid
Definition
Retains shape and volume
Term
Liquid
Definition
Retains volume but not shape
Term
Gas
Definition
Takes the shape and volume of its container
Term
Density
Definition
The amount of quantity of mass per unit
Term
What are the 4 types of pressure?
Definition
Static, Impact, Relative, Absolute
Term
Static pressure
Definition
Pressure in a confined space or not causing motion
Term
Impact pressure
Definition
Pressure caused by motion
Term
Relative pressure
Definition
One pressure in relation to anoter
Term
Absolute pressure
Definition
Sum of the atmospheric and system pressures starting from a theoretical vaccuum
Term
Pascals law
Definition
Pressure applied to an enclosed or confined fluid is transmitted equally in all directions without loss, and acts with equal force on all surfaces
Term
State the effect of a convergent venturi tube
Definition
Increased velocity, decreased pressure
Term
State the effect of divergent venturi tube
Definition
Decreased velocity, increased pressure
Term
Whose law deals with volume and temperature?
Definition
Charles
Term
Whose law deals with volume and pressure?
Definition
Boyle
Term
Newtons Third law
Definition
For every action there is an equal and opposite reaction
Term
What atmospheric range provides the best conditions for jet aircraft flight?
Definition
Stratosphere
Term
Temperature
Definition
Intensity of hotness or coldness of a mass in degrees
Term
List the methods of heat transfer
Definition
Conduction, Convection, Radiation
Term
Conduction
Definition
Molecule to molecule
Term
Convection
Definition
Currents in a fluid caused by uneven heating
Term
Radiation
Definition
High speed particles of machines
Term
Define the principles of machines
Definition
The application of laws, principles and theories that allows us to develop machines to aid us in our daily work
Term
What are the 2 types of machine principles?
Definition
Levers and inclined planes
Term
How does matter change states?
Definition
Chemical or physical means
Term
How is matter usually considered?
Definition
In terms of the energy it contains, absorbs, or gives off
Term
How may matter be classified?
Definition
Either an element or a compound
Term
What particles make up all basic matter?
Definition
Atom and molecules
Term
Volume
Definition
The amount of space an object or substance occupied
Term
Mass
Definition
The amount of matter a body contains
Term
Weight
Definition
A measurement of force cause by gravity on a unit of mass
Term
Gravity
Definition
A force that attracts objects towards the center of the earth
Term
Force
Definition
The total pressure acting on an object
Term
Bernoulli's Principle/ theorem
Definition
Whenever a stream of fluid has its velocity increased at a given point, the pressure at that point is less than the rest of the stream
Term
Boyle's law
Definition
The volume of a given mass of gas varies inversely with pressure when the temperature remains constant
Term
Charle's law
Definition
If the volume of a confined gas is constant, the pressure is directly proportional to the absolute temperature. If the pressure is unchanged, the volume is directly proportional to the absolute temperature
Term
Newton's first law
Definition
Law of inertia
Term
Newton's second law
Definition
F= M x A
Term
What are the 2 measurements of heat?
Definition
BTU and Calorie
Term
BTU
Definition
British Thermal unit: amount of heat required to raise the temperature of 1 pint of water one degree fahrenheit
Term
Calorie
Definition
The amount of heat required to raise the temperature of one gram of water one degree celsius
Term
What is the chemical breakup of the atmosphere?
Definition
78% Nitrogen,21% Oxygen,1% Inert Gases
Term
Atmospheric Pressure
Definition
A column of air with a one square inch base and a height equal to that of the atmosphere will weigh 14.7 pounds per square inch and support 29.92 inches of mercury on the barometric scale at sea level on a standard day
Term
Height atmosphere
Definition
Approximately 200 miles
Term
Troposphere
Definition
The lower limit of the atmosphere which contains weather conditions
Term
Stratosphere
Definition
Average temperature of -69.7 degrees Fahrenheit and provides the best conditions for jet aircraft flight
Term
Mesosphere
Definition
Has conditions that do not allow for gas turbine engine operation due to lack of oxygen
Term
Thermosphere
Definition
The electronically charged protection layer for the earth
Term
How do machines work
Definition
They either multiply force or speed and lost the other
Term
What 3 processes must occur for a machine to work?
Definition
1. input work- work is supplied to the machine.
2. Energy is expanded- work is exerted against friction.
3. Useful Work- output work is done by the machine.
Term
How is a machine's efficiency rated?
Definition
As a number between 0 and 1 which measures the ration of work output dived by work input. The closer to 1, the more efficient the machine.
Term
How does a machine convert an input force to an output force
Definition
Mechanical Advantage
Term
Lever
Definition
The most generally used machine principle. Consists of a rigid bar pivoted at a certain point called the fulcrum.
Term
Inclined Plane
Definition
A smaller input force can be realized by creating a slope and adding distance to create the same output force.
Term
Hydraulics
Definition
The branch of science that deals with the study of liquid in motion.
Term
Whose law deals with hydraulics?
Definition
Pascal's
Term
What is the purpose of hydraulics?
Definition
To move mechanical components accurately and safely with ease.
Term
What are the 8 components that make up a basic hydraulic system?
Definition
1.Reservoir 2. filter 3. pump 4. relief valve 5. selector valve 6. actuating unit 7. Tubing 8. Check valve
Term
Reservoir
Definition
Contains fluid supply
Term
Filter
Definition
Filters contaminants
Term
Pump
Definition
Creates fluid flow
Term
Relief valve
Definition
Relieves excess pressure
Term
Selector valve
Definition
Directs fluid flow
Term
Actuating Unit
Definition
Converts fluid pressure to useful work
Term
Tubing
Definition
Transports fluid
Term
Check valve
Definition
Permits fluid flow in one direction only
Term
What is the greatest maintenance hazard with the hydraulic system?
Definition
Contamination
Term
What are the classes of contaminants?
Definition
Abrasives and non- abrasives
Term
Where do contaminants originate?
Definition
1. Originally contained in the system
2. Introduced from outside sources
3. Created within the system during operation
4. introduced by foreign liquids
Term
How do we control contamination?
Definition
Ensure filters are maintained and ensure minimum contamination
Term
What are the safety hazards when dealing with a hydraulic system?
Definition
Extremely high pressures
Term
Power
Definition
The rate of doing work or the rate of expending energy
Term
Motion
Definition
The act or process of changing place or position
Term
Velocity
Definition
The rate of change of distance with respect to time in a given direction
Term
Acceleration
Definition
The rate of change of velocity
Term
Energy
Definition
The ability to do work or bring about changes in matter
Term
Jet propulsion
Definition
Propelling force generated in the direction opposite to the flow of a gas under pressure, which is escaping through an opening called a jet nozzle
Term
List the conditions of a standard day
Definition
-Barometric pressure of 29.92" of mercury (14.7 PSI at sea level)
-0% Humidity
-59F
-No wind
Term
Brayton cycle
Definition
The thermodynamic cycle of a gas turbine engine to produce thrust. It is a varying volume, constant pressure cycle of events. Commonly called the constant pressure cycle or the combustion cycle
Term
Thrust
Definition
The driving force produced by a gas turbine engine
Term
How is thrust classified?
Definition
Static or Net
Term
What power plant variable has the most effect on thrust?
Definition
Compressor RPM
Term
What effect will a decrease in temperature have on thrust?
Definition
Increased thrust
Term
What type of engine uses only the thrust developed within the engine to produce its force?
Definition
Turbojet
Term
Which engine uses extra stages of turbine wheels to drive reduction gearing to drive a rotating airfoil?
Definition
Turboshaft
Term
Under the engine designation system, which system is the old system used by the Navy and Air Force?
Definition
The 2-digit system
Term
What type of engine is represented by an "x" in the 2-digit system?
Definition
Experimental
Term
Described the manufacturer symbols used in part 2 of the 2-digit system
Definition
Identifies the engine manufacturer using 1 or 2 letter designations
Term
In the 3 digit system, what does a "J" in part 1 identify?
Definition
Turbojet
Term
In the 3 digit system, what does an "F" in part 1 identify?
Definition
Turbofan
Term
In the 3 digit system, what does a "T" in part 1 identify?
Definition
Turboshaft or turboprop
Term
In the 3 digit system, what does a 100-399 in part 1 identify?
Definition
Air Force
Term
In the 3 digit system, what does a 400-699 in part 1 identify?
Definition
Navy
Term
In the 3 digit system, what does a 700-999 in part 1 identify?
Definition
Army
Term
Where is the data plate located?
Definition
The forward external portion of the engine
Term
What information does the data plate contain?
Definition
-Engine serial number
-Engine model designation
-Manufacturer code
Term
What speed does a ramjet engine require to sustain operation?
Definition
250 MPH
Term
Who developed the "Aelipile" and when?
Definition
Hero of Alexandria, 150 B.C.
Term
Who developed the turbine-powered stamp mill, and when?
Definition
Giovanni Branca, 1629
Term
Who produced the first steam jet horseless carriage and when?
Definition
Ferdinand Veriest, 1678
Term
When was the earliest use of solid-fuel rockets as weapons?
Definition
1100 AD
Term
What type of engine was used as a German robot bomb, or V-1 weapon, in 1941?
Definition
Pulsejet
Term
When was the first gas turbine engine built?
Definition
1902 at Cornell University
Term
What was the first application of a turbojet engine?
Definition
To drive a supercharger for reciprocating engines ( General electric in 1918)
Term
When was the first jet propelled flight?
Definition
27 August 1939
Term
When was the test flight of the Whittle (W1) turbojet?
Definition
14 May 1941
Term
Constant Velocity
Definition
The distance travelled per unit of time
Term
What are the 4 continuous and constant events in the Brayton Cycle?
Definition
Intake, Compression, Combustion, Exhaust
Term
Which of Newtons laws of motion are applied to obtain thrust?
Definition
2nd and 3rd
Term
What are newtons laws called?
Definition
Laws of force and motion
Term
What is the name for newtons 1st law?
Definition
Laws of inertia
Term
What is the name of for Newtons 2nd law?
Definition
Law of force and acceleration
Term
What is the name of Newtons 3rd law?
Definition
Law of interation
Term
What is static thrust?
Definition
The thrust produced when the aircraft or engine has no forward motion
Term
How are engines rated by their manufacturers?
Definition
In static thrust under standard day conditions
Term
Net thrust
Definition
The thrust available to power the aircraft in flight
Term
How is power plant RPM expressed?
Definition
In percent of engine's maximum possible compressor speed/RPM
Term
How will an increase in RPM affect thrust?
Definition
Increases thrust
Term
How will a decrease in RPM affect thrust?
Definition
Decreases thrust
Term
How will an increase in outside air temperature affect thrust?
Definition
Decreases thrust
Term
How will a decrease in outside air temperature affect thrust?
Definition
Increases thrust
Term
OAT
Definition
Outside Air Temperature
Term
How will an increase in barometric pressure affect thrust?
Definition
Increases thrust
Term
How will a decrease in barometric pressure affect thrust?
Definition
Decreases thrust
Term
Humidity
Definition
The amount of water vapor present in the air at any given time
Term
Relative Humidity
Definition
The amount of moisture in the air relative to the maximum amount that the air could contain at the same temperature expressed as a percent
Term
How will an increase in humidity affect thrust?
Definition
Decreases thrust
Term
How will a decrease in humidity affect thrust?
Definition
Increases thrust
Term
What does a Y prefix represent?
Definition
Restricted service
Term
When is the prefix dropped from the engine designation?
Definition
When testing is complete
Term
What branches used the 2-digit system?
Definition
Navy and Air Force
Term
In the 2-digit system, what are the 3 possible type symbols?
Definition
-J-Turbojet
-TF-Turbofan
-T-Turboshaft/ Turboprop
Term
In the 2-digit system, how can you tell which service the engine was designed for?
Definition
In part 1, even numbers starting from 30 represent Navy. Odd numbers from 31 represent Air Force
Term
In the 2-digit system, what does part two contain?
Definition
The engine manufacturer symbol, wither 1 or 2 letters
Term
In the 2-digit system, when is a suffix used?
Definition
When a minor modifications are incorpoated
Term
In the 3-digit system, how does the type designator for turbofan engine differ?
Definition
Instead of TF, F is used to identify turbofan
Term
In the 3-digit system, what does a 100-399 represent?
Definition
Air Force
Term
In the 3-digit system, what does a 400-699 represent?
Definition
Navy
Term
In the 3-digit system, what does a 700-999 represent?
Definition
Army
Term
Where is the front frame mounted?
Definition
On the front of the compressor section
Term
What is the purpose of the front frame section?
Definition
To receive air from the aircraft air inlet duct and pre-swirl it in the direction of compressor rotation to prevent shock
Term
What are the purposes of the compressor section?
Definition
*Supplies compressed air in sufficient quantities to satisfy the requirements of the combustion section
*Supply bleed air
Term
The axial-flow compressor consists of what?
Definition
Rotating airfoils (rotor blades) and stationary airfoils ( stator vanes)
Term
Where is the diffuser located?
Definition
It forms the compressor section rear frame
Term
How are compressor blades attached to the compressor?
Definition
By dovetail, fir-tree root, or bulb
Term
What develops the highest point of pressure in the compressor section?
Definition
The diffuser
Term
What component is housed in the front frame section?
Definition
Inlet Guide Vanes (IGV's)
Term
What purpose do inlet guide vanes perform?
Definition
They are hollow to allow for hot air from the engine to circulate through the vanes to prevent ice from forming. They also accommodate tubes to carry oil to and from the front main bearing
Term
What are the 6 sections of the gas turbine engine?
Definition
*Front Fame section
*Compressor section
*Combustion section
*Turbine Section
*Exhaust Section
*Accessory Section
Term
Where is the compressor section located?
Definition
Between the front frame section and the combustion section
Term
What are the 5 main components of the compressor
Definition
*Casing
*Rotor Assembly
*Stator Assembly
*Guide Vane Assembly
*Diffuser
Term
What components make up 1 stage of compression?
Definition
Rotor assembly and stator assembly
Term
What is the defining characteristic of an axial-flow compressor?
Definition
It compresses the air in a direction that is parallel to the axis of the engine
Term
What type of compressor casing is most common?
Definition
Drum type, split horizontally for ease of maintenance
Term
What component is housed by the compressor casing?
Definition
Stator assemblies
Term
What are the 3 components of a rotor assembly?
Definition
Shaft,disks, blades
Term
How can rotor blades be locked?
Definition
Peening, pins, locking wire and keys
Term
What materials are blades and vanes made from?
Definition
Stainless steel, aluminum or titanium
Term
What is the function of the compressor rotor blades?
Definition
Accelerate air rearward
Term
Describe stator asseblies
Definition
Rows of stationary vanes dove-tailed into split-rings and mounted to the compressor casing
Term
What is the function of the stator vanes?
Definition
Control air direction for better efficiency
Term
Where are the exit guide vanes located?
Definition
The compressor exit
Term
What is the purpose of exit guide vanes?
Definition
To straighten compressor discharge air to eliminate turbulence
Term
What is the function of the diffuser?
Definition
Develops a pressure wall to prevent reverse flow of combustion gases back into the compressor
Term
What are the 2 types of axial-flow compressors?
Definition
Single rotor (solid-spool) dual rotor (split-spool)
Term
Which stage of the turbine drives the N-1 compressor?
Definition
The last stage or stages
Term
Which stage of the turbine drives N-2 compressor?
Definition
The first stage
Term
What are the 3 advantages of the axial-flow compressor
Definition
*High peak efficiencies
*Small frontal area
*Increased pressure rise by more stages with minimum pressure loss between stages
Term
What are the 3 disadvantages of an axial-flow compressor?
Definition
*Heavy weight
*Difficult to manufacture- high cost
*High starting power requirements
Term
Where is the combustion section located?
Definition
Between the compressor and turbine sections
Term
What is the purpose of the combustion section?
Definition
To burn the fuel/air mixture, adding heat energy to the mass airflow from the compressor to drive the turbine, which drives the compressor and accessories
Term
What functions does the combustion section perform?
Definition
*mix the fuel and air to the proper ratio
*Burn the fuel/air mixture
*position the flame within the chamber liner
*Cool the gases to a temperature that the turbine can withstand
*deliver the gases rearward to the turbine section
Term
What are the 5 components of the combustion section?
Definition
*Casing (housing)
*Chambers
*Ignitor plugs
*Fuel Nozzles
*Fuel drain
Term
What is the purpose of the ignitor plugs?
Definition
Provide an air gap for the high-energy spark to ignite the fuel/air mixture
Term
What are the 2 types of fuel nozzles?
Definition
Simplex and Duplex
Term
Describe the duplex fuel nozzle
Definition
It is widely used due to its good spray characteristics under all operating conditions
Term
Describe the simplex fuel nozzle
Definition
It has a spray pattern which is limited in use
Term
Fuel drain
Definition
It is located on the bottom of the combustion casing. It provides a means of draining residual fuel during engine shutdown or abnormal starts
Term
What are the 2 types of combustion chambers?
Definition
Annular and Can-Annular
Term
Annular combustion chamber
Definition
Uses limited space to permit better mixing of the fuel and air for more efficient combustion
Term
Can-Annular combustion chamber
Definition
Individual chambers are placed side-by-side to form a circle of cans inside a single casing
Term
Where is the turbine section located?
Definition
Between the combustion section and the exhaust section
Term
What is the purpose of the turbine section?
Definition
To extract energy from the expanding gases from the combustion section and convert the gases to shaft horse power to drive the compressor and engine-drivenaccessories
Term
What determines the amount of energy the turbine extracts?
Definition
*Compressor size
*Number of engine-driven accessories
*Reduction gearboxes to drive propellers
*Rotary airfoils driven by shafts
Term
What are the components of the turbine section?
Definition
*Casing(housing)
*Nozzle assemblies
*Turbine rotor assemblies
Term
Turbine housing
Definition
Houses the turbine rotor assembly and provides mounting and support for the turbine nozzle assemblies
Term
Where are nozzle assemblies located?
Definition
Directly aft of the combustion chamber assembly and in front of each preceding stage of turbine rotor blades
Term
What is the function of nozzle assemblies?
Definition
*to convert heat and pressure energy into velocity energy
*Direct gases to the turbine rotor blades at the most efficient angle
Term
What is the purpose of the turbine rotor assembly?
Definition
To convert velocity energy from the turbine nozzle into mechanical energy (shaft ) to drive the compressor and engine-driven accessories
Term
What are the components of the turbine rotor assembly?
Definition
*turbine blades
*rotor disk
*rotor shaft
Term
What is the purpose of the turbine blades?
Definition
Extract energy from the expanding gases and transmit it to the rotor disk
Term
What are the 3 types of rotor blades?
Definition
*impulse
*Reaction
*Impulse-reaction
Term
When are the impulse turbine blades used?
Definition
Low-thrust engines
Term
When are reaction type turbine blades used?
Definition
Medium-thrust engines
Term
When are impulse-reaction type turbine blades used?
Definition
High-thrust engines
Term
What is the purpose of the rotor disk?
Definition
Provide mounting for the rotor blades and transmit power from the blades to the turbine rotor shaft
Term
What is the purpose of the turbine rotor shaft?
Definition
To transmit shaft horsepower from the rotor disks to the compressr
Term
Where is the exhaust section located?
Definition
Aft of the turbine section
Term
What are the purposes of the exhaust section?
Definition
*straighten and direct the gases rearward
*Convert the gases into a solid jet stream
*Impart a final boost in velocity
Term
What are the components of the exhaust section?
Definition
*exhaust duct
*Inner cone
*Struts
*Tailpipe
*exhaust nozzle
*thermocouples
*insulation blankets
Term
Where is the exhaust duct located?
Definition
Bolted to the turbine case rear flange
Term
What are the purposes of the exhaust DUCT?
Definition
*Collect the exhaust gases and deliver them to the exhaust nozzle
*Provide mounting for the thermocouple assemblies
*provide mounting for the struts which support the inner cone
Term
How is the inner cone held in place?
Definition
With struts or a combination of struts and supporting rods
Term
What is the purpose of the inner cone?
Definition
To prevent turbulence
Term
Why is the design of the inner cone important?
Definition
It allows the gases to gradually come together to form a solid jet stream
Term
Why would the inner cone have small holes in it?
Definition
To allow for reverse flow to cool the last stage of the turbine
Term
Where are the struts located?
Definition
Between the housing and the inner cone
Term
What are the purposes of the struts?
Definition
*Position and support the inner cone
*straighten the swirling gases leaving the turbine
*Provide airfoils around the supporting rods to prevent damage
Term
Where is the tailpipe located?
Definition
Bolted to the rear flange of the exhaust duct
Term
What is the purpose of the tailpipe
Definition
To carry exhaust gases away from the airframe
Term
Where is the exhaust nozzle located?
Definition
Attached to the rear flange of the exhaust duct housing, tail pipe, or afterburner duct depending on the aircraft designation
Term
What is the purpose of the exhaust nozzle?
Definition
To impart a final boost in velocity to gases leaving the engine
Term
What are the 2 types of exhaust nozzles?
Definition
Fixed area and variable area
Term
Describe a fixed area exhaust nozzle
Definition
A convergent designed duct with no moving parts which is used on engines producing sub-sonic velocities
Term
Describe a variable area exhaust nozzle
Definition
A convergent/ divergent designed duct which opens and closes automatically according to fuel flow and throttle position which allows for increased exhaust nozzle area during afterburner operation
Term
Where are thermocouples located?
Definition
Forward, aft, and between stages of turbine. Location is determined by the manufacturer
Term
How do thermocouples work
Definition
The produce an electrical signal in proportion to exhaust gas temperatures
Term
What is the purpose of thermocouples
Definition
To monitor engine operating conditions through the use of the temperature indicating system
Term
Where are insulation blankets found?
Definition
Between the engine and the airframe
Term
Why are insulation blankets used?
Definition
To protect the airframe from heat damage
Term
Where is the accessory section located?
Definition
Normally mounted at the front of the compressor rotor or on the lower part of the compressor housing
Term
What are the 2 main gearbox types?
Definition
*Power take- off gear box at the center front of the compressor hub
*Accessory gear box located near the bottom of the compressor
Term
What are the purposes of the accessory section?
Definition
To change the compressor rotor speeds to suitable drive speeds for engine accessories
*To provide passages and tubing for lubrication of the accessory drive train
*To provide mounting pads for engine-driven accessories
Term
What happens to airflow as it passes through the compressor section?
Definition
*pressure increases
*temperature increases
*Velocity stabilizes
Term
What happens to airflow as it passes through the combustion section?
Definition
*Pressure decreases
*Temperature increases
*Velocity Increases
Term
What happens to airflow as it passes through the turbine section?
Definition
*Pressure decreases
*temperature decreases
*velocity increases
Term
What happens to airflow as it passes through the exhaust section?
Definition
*pressure decreases
*temperature decreases
*velocity increases
Term
Describe APU
Definition
A small, gas turbine engine located within the airframe of the aircraft
Term
What are the 4 types of power provided by an APU?
Definition
*Hydraulic
*Electrical
*Mechanical
*Pneumatic
Term
What is the bleed air (pneumatic power) from an APU used for?
Definition
*main engine starting, available from the start bypass valve
*aircraft air conditioning, available at the pneumatic power source outlet
Term
Where is the APU pneumatic power tapped for main engine starting?
Definition
Start bypass valve
Term
WHere is the APU pneumatic power tapped for aircraft air conditioning?
Definition
Pneumatic power source outlet
Term
What is APU hydraulic and electrical power used for?
Definition
During ground maintenance allowing the aircraft to be independent of support equipment
*For emergency power while in flight
Term
How can APU hydraulic and electrical power be used in emergency situations?
Definition
Independently or simultaneously
Term
How is mechanical power available from an APU?
Definition
As shaft power at the main output drive pad
Term
What are the 2 major assemblies of the APU?
Definition
*Power section assembly
*Gearbox assembly
Term
What are the main components of the APU power section assembly?
Definition
Compressor, combustion, and turbine
Term
Describe the APU power section assembly compressor section
Definition
It is a centrifugal compressor which supplies air for combustion and bleed air requirements
Term
Describe the APU power section assembly turbine section
Definition
Single-stage turbine of the radial inflow design
Term
How are the APU power section assembly compressor and turbine section joined?
Definition
On a common shaft to make a single balanced rotating assembly and supported by two main bearings
Term
Describe the APU power section assembly combustion section
Definition
Chamber of the annular type provides mounting pads for the six fuel nozzles, one ignitor plug and combustion drain valve
Term
What is the purposes of the APU gearbox assembly?
Definition
*house the reduction gear train
*Provide mounting pads for all or some accessories
Term
What accessories can be mounted on the APU gearbox assembly?
Definition
*Fuel pump and accelerator
*oil pump assembly
*hydraulic starter
*speed sensor
Term
What are the 6 APU systems?
Definition
*starting system
*fuel system
*lubrication system
*ignition system
*electronic sequencing unit (ESU)
*Safety control system
Term
How is starting accomplished by an APU starting system?
Definition
Hydraulically using an aircraft-mounted hydraulic accumulator
Term
What component provides hydraulic pressure required by the APU hydraulic starter?
Definition
Nitrogen-charged accumulator
Term
What causes the hydraulic charge to release? (APU starting system)
Definition
Actuation of the APU control switch in the cockpit/flight station
Term
Describe the APU fuel system receive its fuel supply from?
Definition
The aircraft fuel system
Term
Describe the APU lubrication system
Definition
Provides both pressurized and splash lubrication for all gears, shafts and bearings within the engine
Term
Describe the APU ignition system?
Definition
Capacitor discharge type that consists of an ignition exciter, ignitor lead, and ignitor plug
Term
What are the 3 parts of the APU ignition system?
Definition
*Ignition exciter
*Ignitor lead
*Ignitor Plug
Term
What is the purpose of the Electronic Sequence Unit?
Definition
Provides the APU with programmed events such as starting, operational checks and overspeed protection
Term
Describe the APU safety control system
Definition
Provides automatic starting of the APU as well as safety features to shut down the unit automatically or manually
Term
What conditions cause the APU safety control system to automatically shut down the system?
Definition
Oil pressure falls below minimum or turbine Exceeds maximum RPM
Term
What happens if there is a fire in the APU?
Definition
An APU Fire warning light will illuminate in the cockpit/flight station. Pulling the T-Handle of the APU control switch will arm the fire extinguisher and remove 28V DC from the control switch
Term
What are the 3 steps to APU operation?
Definition
*Power is developed through compression of ambient air by a centrifugal compressor
*Compressed air is mixed with fuel that is ignited to drive the turbine
*The rotating shaft power of the turbine wheel drives the compressor, accessories, and main output drive pad
Term
What is acceptable O-Level maintenance on an APU?
Definition
*Periodic inspection
*removal/replacement of components
*removal/replacement of the entire APU
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