Exam 2 Flashcards
Ch. 6-?
The internal combustion engine used in our modern aircraft is a form of?
Heat engine
The mixture ratio of fifteen pounds of air to one pound of gasoline
Stoichiometric
What provides low pressure at the discharge nozzle of a float carburetor?
Carburetor Venturi
Why are float carburetors more susceptible to icing (at least two reasons)?
Fuel evaporation Decrease in air pressure in the venturi
Under what conditions should partial carburetor heat not be used?
CAT temperatures above 0*C
Under what conditions would the use of carburetor heat be detrimental?
In unimproved surfaces, such dirt, because the carburetor heat is unfiltered contaminants picked up from the ground could damage the engine
When should carburetor heat be used on the ground?
Engine starting in very cold temperatures Shutting off the engine w/ mixture control to prevent cold air from passing through the engine after combustion stops, but the engine has not yet stop turning Under conditions in extremes of high humidity and very high or low temperatures
Does application of carburetor heat richen or lean the mixture? How and why?
Richens the mixture Hot air further richens the mixture then decreases the RPM
What are the advantages of the pressure carburetor over the float carburetor?
Fuel distributed by mass Better metering system Allows for auto-mixture
What are the functions of the spider?
Distributes the fuel evenly to all the cylinders Provides a positive shut-off when the mixture is placed in the idle-cut position
What are the advantages of a fuel injection system, as a fuel metering system?
Provision is made in the pump to remove all vapor from the fuel and return it to the tank A by-pass check valve around the pump so fuel from the boost pump may flow to the fuel control for the starting
Why is it important for the pilot to know an engines exhaust gas temperature?
There is a relationship between the temperature of the exhaust gas temperature and the mixture ration being burned
(pounds of fuel burned per hour)/(brake horsepower)
specific fuel consumption
What is the importance of a fuels critical pressure and temperature?
Once it reaches a certain pressure and temperature, it will explode rather than burn evenly (otherwise known as detonation)
Why is tetrathyl lead sometimes added to aviation fuel?
For anti-detonation in larger aircraft
Why are two numbers used for identifying aircraft fuel octane (i.e. 100/130)?
Recognizes octane or performance number and the amount of tetrathyl
What does a carburetor air temperature gauge permit a pilot to do?
Helps indicate potential icing conditions Indicates whether or not a carburetor heat is necessary
Where are the fuel injection nozzles located on a typical light aircraft engine?
Screws into the cylinder head near the intake port
What is the difference between detonation and pre-ignition?
Pre-ignition: engine misfire prior to ignition Detonation: Engine misfire after ignition
What is critical altitude?
Term used to describe altitude where the throttle is fully open in order to achieve the desired power setting
Why does the MAP increase when RPM is decreased when there is no change of throttle position?
Less exhaust at back pressure; atmospheric pressure decreases Less force below piston; atmospheric pressure in crankcase is less Colder air is at higher altitudes; cold air is more dense
Which hass the higher operating speed and temperature, a turbocharger or a supercharger?
Turbocharger
An indication of unregulated power change that results in the continual drift of manifold pressure
boot strapping
Excessive MAP (Manifold pressure)
overboost.
Which cockpit control will change the MAP on an engine?
The throttle changes the MAP on an engine with constant speed prop
Which cockpit control will change the RPM on an engine?
Propeller control changes the RPM on an engine with constant speed propeller
Engine that requires MAP in excess of sea level pressure to produce its rater power
ground boosted engine.
Internal combustion engine in which air intake depends solely on atmospheric pressure and which does not rely on forced induction through a turbo or supercharger
normally aspirated engine.
Equipped with a turbo or supercharger (or both) to give improved engine performance
normalize engine.
Driven by the hot, high velocity exhaust gases that are being expelled from the engine.
supercharger.
Applies to an engine system that has both a turbocharger that boosts air pressure before the carburetor and a supercharger that further boosts pressure of the fuel:air mixture
turbocharger
Controls the volume of the exhaust gas that is directed onto the turbine and thereby regulates the speed of the rotor and the output of the compressor
waste-gate
One side of the diaphragm in the differential pressure control senses air pressure upstream fro the throttle
deck pressure
Limits maximum MAP, thus preventing overboost by limiting the deck pressure
density controller
Regulates the position of the waste-gate valve to maintain a pre-set pressure differential across the throttle so that if the pilot opens the throttle, there will be a response
differential pressure controller
In an automatic turbo charger, what provides the force to open the waste gate? To close it?
Open: decrease oil pressure Close: increased oil pressure
What is the purpose of an alternate air valve and how does it work?
Valve in the induction system that directs air either from the air filter or from a point inside the engine nacelle into the carburetor or the fuel injection system
The altitude above which the turbocharging (or supercharging) system can no longer maintain seal level power
critical altitude
What is the purpose of the intercooler and how does it work?
Reduces the temperature before compressed air reaches the engine 1) Fresh outside air is collected and piped to the intercooler so that it flows over and cools the tubes 2) As the induction air charge flows through the tubes of the intercooler, heat is removed and that charge is cooled to a temperature the engine can tolerate without detonation occurring
A turbocharger compresses
Air only
A supercharger compresses?
Fuel/Air mixture
List three basic types of oxygen equipment and the altitude limitation of each.
Fixed: Large: and High performance aircraft OBOGS: On board oxygen generating system; reliable, safer, and requires less maintenance Portable: Smaller aircraft; less expensive than fixed system, but last shorter than fixed; Types: Diluter, Diluter demand, Pressure demand, Continuous flow
What is the color code for oxygen cylinders and other components?
Green
Regarding oxygen safety precautions, what material must not come into contact with oxygen?
Hydrocarbons
What is meant by ‘demand’ when discussing an oxygen ‘pressure-demand’ regulator?
Only uses it when oxygen is inhaled by the user
Defined as a change in cabin pressure faster than the lungs can decompress
explosive decompression
Defined as a change in cabin pressure where the lungs decompress faster than the cabin
rapid decompression
List five basic requirements needed to have a cabin pressurization system?
- Cabin Structure 2. Source of compressed air 3. Means of regulating the temperature of air flowing into the cabin 4. Means of regulating the pressure and rate of pressure change in the cabin 5. Means of controlling the rate of outflow of air from the cabin
What are the purposes of positive and negative cabin pressure relief valves?
To regulate cabin pressure by either releasing air in out and operates automatically. Safety
What is meant by ‘isobaric’ pressurization range?
Isobaric: crew has control
What is meant by ‘pressure differential’ range?
Pressure differential: Crew doesn’t have control over pressure
What component physically meters the flow of air from the cabin of a pressurized aircraft?
Outflow Valve
The flow of electrons or the presence of flowing electrons of the ability (potential) of electrons to flow
electricity
The smallest particle of any matter that is able to exhibit the properties and characteristics of that matter
atom
A very small, electrically charged particle that exists as a part of every atom
electron
An electrical force outside the atom can attract electrons away from the outer ring and leave the atom in an unbalanced condition
ion
Rate of one electron flow
current.
When electrons flow the opposite to their flow
resistance
The basic statement which says in effect that the current that flows in a circuit is directly proportional to the voltage (pressure) that causes it, and inversely proportional to the resistance (opposition) in the circuit
Ohm’s Law
Atoms with loosely held electrons
Conductor
Made up of materials which are composed of atoms which hold their outer electrons more tightly so that electrons can’t flow in response to an electromotive force
Insulator
When a coulomb flows past a point in one second One ampere is one amp
Ampere
The standard unit of resistance The resistance at a specific temperature of a column of mercury having a specified length and weight
Ohm
The unit of electrical pressure The amount of pressure required to force one amp of flow through one ohm of resistance
Volt.
The measure of the rate of energy conversion
Watt.
Sharp points on which static charges concentrate and will discharge into the air before they can build up on the smooth surface sufficiently high to jump across the hinges causing hinge bearing damage and radio interferences
Static Discharge Wick.
The charge in a circuit
Electricity
Briefly describe the two kinds of ‘electron flow.’
Direct Current: Unidirectional Alternating Current: Alternates direction
Which direction do electrons flow in an electrical circuit?
High to low
E is Voltage I is current R is resistance E=(I)(R)
formula for ‘Ohm’s Law
Name two types of electrical currents.
Direct Current (DC) Alternating Current (AC)
Cycles per seconds in AC
Hertz
What is meant by ‘flux’ or ‘lines of flux.’
Lines of magnetic force
Why/how are lines of flux important in the generation of electricity?
Lines of magnetic flux pass between the poles of a magnet, and if a conductor is moved through these lines of flux, they will transfer to the conductor and force electrons to flow through it
A ____ gyro combines a directional gyro with a direction sensing instrumentation.
slayed
A _____ instrument is typically used to measure high temperatures.
thermocouple
A _____ is an instrument that displays engine RPM.
tachometer
A _____ type instrument is used to measure high pressures.
bourdon
A rate gyro uses the gyroscopic characteristics of _____.
precession
A vertical speed indicator measures the rate of change of _____ pressure.
static
absolute altitude
The vertical height of an aircraft above ground level
Air-driven gyroscopic instruments require very _____ air.
clean
All elevations on aeronautical charts are measured from _____ _____ _____
mean sea level
Altimeters installed in aircraft that operate under instrument flight rules must have their accuracy checked every _____ calandar months.
24
An _____ gives the pilot an indication of the load imposed on the aircraft structure in terms of G’s.
accelerometer (g-meter)
An A&P maintenance technician _____ disassemble and repair an aircraft instrument.
cannot
An aneroid barometer measures _____ pressure.
absolute
An attitude gyro uses the gyroscopic characteristic of _____ _____ _____.
rigidity in space
An instrument that measures aircraft speed relative to the speed of sound is called a _____.
machmeter
ARING
Aeronautical Radio Inc
Because navigation charts are laid out according to the geographic poles and a magnetic compass points to the magnetic poles, the difference between the positions is called _____.
variation
Bourdon tube
gauges used to indicate lower pressures uses a flexible tube that uncoils and coils made from brass,bronze or copper.
Compass _____ is caused by the magnetic fields in the aircraft that interfere with those of the earth.
deviation
compass correction card
small card mounted near the magnetic compass to show the pilot the amount of deviation error for each heading
compensator magnet
used to correct distortion of the earths field from a nearby iron structure
CRT
Cathode Ray Tube
Density altitude _____ a direct measurement
is not
deviation
error in the indication of a magnetic compass caused by magnetic fields in the aircraft.
dielectric
insulating material that can store electrical energy in an electrostatic field
Direct current electrical fuel quanitity indicators use a variable _____ as a tank unit, or sender.
resistor
EADI
Electronic Attitude Deviation Indicator
EFIS
Electronic Flight Instrument System
EHSI
Electronic Horizontal Situation Indicator
Encoding altimeter
pressure altimeter used to send a signal to the air traffic controller on the ground showing the pressure altitude the aircraft is flying.
Flight level 320 is a pressure altitude of _____ feet.
32,000
For navigation and flight planning purposes, a pilot is most interested in _____ airspeed.
TRUE
Fuel pressure is typicall measured in ______.
PSI
gimbal ring
base that permits an object to tilt freely in any direction, in effect suspending the object so that it will remain horizontal even when it is tipped
Greenwich mean time is also known as ______ time.
zulu or Z
How do variations in temperature affect the altimeter?
warm air reading will be lower than true altitude / cool air reading will be higher than true altitude
In a capacitance type fuel quantity indicating system the two dilectric materials used are _____ and _____
air fuel
Indicated airspeed
the airspeed read directly from the airspeed indicator on an aircraft, driven by the pitot-static system. It uses the difference between total pressure and static pressure
Inspection points of the altimeter
scale error, hysteresis, ag=fter effect, friction, case leak, barometric scale error
It _____ permissible to cut off excess length of thermocouple leades.
is not
Lines of equal variation on aeronautical charts are called _____ lines.
isogonic
lubber line
line that indicates the nose of an aircraft
Mach _____ is flight at an airspeed of 95% the speed of sound.
0.95
pitot pressure
RAM air pressure used to measure airspeed
Pitot tube blockage
ASI remaines at the existing airspeed and does not reflect actual changes in speed / at altitudes above where the blocakge occured the ASI displays a higher than actual airspeed increasing steadily as altitude increases / At lower altitudes the ASI displays a lower than actual airspeed decreasing steadily as altitude decreases
precession
one of the two basic characteristics of a gyroscope. Precession causes a force applied to a spinning gyroscope to be felt not at the point the force is applied but at a point 90 degrees in the direction of rotation from that point
Pressure altitude may be converted into density altitude by correcting the pressure altitude for non-standard _____.
temperature
Pressure is measured in three ways. These are:
Absolute, gauge, differential
Radio altimeter
an absolute altimeter that measures the height of the aircraft above the terrain. Also known as radar altimiter
Ratio altimeters provide an indication of the aircraft’s _____ altitude above _____ _____.
absolute ground level
Requirements for Inspection of the pitot-static system
FAR Part 43 appendix E leak check, trapped water, damage to lines, damage to structure
Resistance change-type temperature measuring instruments may use either a _____ _____ or a _____.
wheatstone bridge or ratiometer
rigidity in space
characteristic of a gyroscope that prevents its axis of rotation tilting as the earth rotates. This is used for attitude gyro instruments
RSVM
Reduced Vertical Seperation Minimum
RSVM Equipment
FAR part 91 appendix G aircraft must have: 2 indipendent altitude measurement systems / 1 automatic altitude holding system / altitude alerting system / altitude alerting system
Servo altimeter
pneumatic altimeter in which the bellows move an electrical pickup whose signal is amplified enough for it to drive a servo motor that moves the drums and pointer in the display.
Static port blockage
ASI will function but produce inaccurate indications. At the altitude where the blockage occurs, airspeed indications would be normal / At altitudes above which the ports became blocked the ASI displays a lower than actual airspeed continually decreasing as altitude is increased / At lower altitudes the ASI displays a higher than actual airspeed increasing steadily as altitude decreases
static pressure
senses the pressure of the atmosphere at the altitude at which the aircraft is flying
Swinging a compass compensates for _____.
deviation
Temperature bulb
a temperature probe mounted on the surface of the aircraft. The probe is designed to bring the air to rest relative to the aircraft. As the air is brought to rest, kinetic energy is converted to internal energy. The air is compressed and experiences an adiabatic increase in temperature. Therefore total air temperature is higher than the static (or ambient) air temperature.
The _____ is used by the pilot of a twin-engine aircraft to synchronize the propeller rotations.
synchroscope
The _____ measures the absolute pressure of the air surrounding the aircraft.
altimeter
The altimeter source valve in the aircraft flight instrument system is in the _____ system.
static
The altitude shown on an altimeter when standard sea level pressure is put into the barometric window is called _____ altitude.
pressure
The altitude shown on the altimeter when the local altimeter setting is placed in the barometric window is called _____ altitude
indicated
The artificial horizon indicator senses rotation of an aircraft about which two of its axes?
pitch (lateral) roll (longitudinal)
The dielectric value of air is ____.
one
The dielectric value of fuel is approximately _____ but varies according to its temeprature
two
The difference between atmospheric pressure and the pressure being measured is called _____ pressure.
gauge
The instrument that measures the differential pressure between the tailpipe total pressure and the compressor inlet total pressure of a turbine engine is the _____ _____ _____ indicator.
engine pressure ratio
The line of zero variation is known as the _____ line.
agonic
The manifold pressure gauge measures the _____ pressure inside the induction system of a reciprocating engine.
absolute
The mass type flometer is the _____ accurate method of measuring fuel flow
most
The rate of climb indicator is more properly known as the _____ _____ indicator.
vertical speed
The rotor vanes of a dry-type vacuum pump are made of _____.
carbon
The scale in the barometric window of an altimeter may be calibrated in _____ of _____ or _____.
inches of mercury or millibars
The tests required for a static system of an aircraft operated under instrument flight rules is described in FAR part _____.
91.411
The turn and slip indicator is actually two instruments in one housing, the non gyroscopic is called a _____.
inclinometer
The turn and slip indicator senses rotation about the _____ axis of the aircraft.
vertical
The two basic characteristics of a gyroscope that makes it useful as a flight instrument are _____ _____.
rigidity in space and precession
The two pressures sensed by the airspeed indicator are:
pitot static
The uncorrected reading of an airspeed indicator is called _____ airspeed.
indicated
Thermocouple
electrical device used to measure temperature
Three basic pressure operated instruments are:
altimeter ASI airspeed indicator VSI vertical speed indicator
Three instruments that are connected to the static system are:
airspeed ASI altimeter and vertical speed VSI
To prevent ice from obstructing a pitot tube, _____ heaters are used.
electric
True altitude
The vertical distance of an aircraft above sea level
Two magnetic compass errors that a pilot must compensate for while in flight are _____ error and _____ error.
turning acceleration
Two major disadvantages to venturi systems for driving flight instruments are:
susceptible to icing and it produces no vacuum until the airplane is flying
Under standard day conditions, atmospheric pressure is _____ inches of mercury or _____ psi.
29.92 and 14.7
Under what condition will true altitude be lower than indicated altitude?
colder than standard air temperature
Vmo
maximun operating limit speed
Vne
never exceed speed
Vno
Maximum structural cruising speed or maximum speed for normal operations
what altitudes are included in the RSVM rules?
FL 290-410
What FAR requires the inspection of a pitot-static system?
91.411
What is the maximun structural cruising speed?
Vno
What specifies the requirement and frequency of an inspection of the altimeter system?
91.411
When must a leak check of the pitot-static system be performed?
every 24 months, anytime the system is opended for repair/service, if the pilot reports a problem, or any surface damage near a static port
When static ports are exposed to distubed air, the results are altimeter system errors known as _____ errors.
position
where does it state the items to be inspected in the altimeter?
Part 43 appendex E
Where is the scope of the inspection of a pitot-static system explained?
Part 43 appendix E
Regulates the fuel flow into the carburetor intake
Metering jet
Allows for engine operation with the throttle closed
When the throttle butterfly valve is almost closed, the idler opens two or three small holes (discharge ports) to supply fuel
Idle System
Supplies extra fuel during increases in power: when the throttle is opened quickly, the vacuum created by the pistons could gulp large amounts of air – too much for a given amount of fuel. The initial rush of air over the venture is so quick that fuel can’t be sucked through the nozzle of the metering jet fast enough, and the result would be a sudden hesitation in power
Accelerator pump
Determines the ratio of fuel and air.
Position of needle controls the flow of fuel (like cutting off the water supply to your toilet tank, or opening the valve to full)
Mixture Control
Understand the Carburetor System Operation
- As the airflow from the engine passes over the venturi of a carburetor, the velocity of the fluid increases, the pressure decreases
- The decrease in pressure pulls the fuel from the float chamber
- Once the fuel is discharged at the main nozzle, it is atomized with air, and the ratio of fuel/air continues through the induction system to the combustion chamber in the cylinders
Understand the Management of Fuel/Air Mixture
- Air density varies with both temperature and altitude
The problem is that the volume, not the weight, of air passing through the venture, regulates the amount of fuel flowing through the carburetor
Therefore, as you gain altitude, air gets less dense, and less fuel is needed to maintain optimum fuel/air mixture
Thus, you must lean the mixture
A fuel/air ratio that produces the greatest amount of power for a given consumption of fuel
Economy vs. Power
-Maximum Power
Economy vs. Power
-Best Economy
Mixture that provides the lowest specific fuel consumption.
- Leaner than best power
- Some power and speed is sacrificed
Leaning-three methods.
- Tachometer Method- Set desired cruise setting then gradually lean the mixture until:
- Best Power-tachometer peaks.
- Best Economy-roughness, then enrichen until the engine runs smooth again.
- EGT Method- An internal combustion engine will achieve maximum thermal efficiency and have the most efficient ratio when it reaches peak EGT
- Fuel Flow Method
When fuel is discharged into the low-pressure area of the venturi, it evaporates
Evaporation causes a rapid cooling of the air, the walls of the venturi, and the walls of the carburetor
If there is water vapor in the air, carb ice may form
Carburetor Ice
Recognition and Prevention of Carburetor Ice
- may result in as much as a 70 F drop in temperature
- decrease in engine RPM.
- Carburetor heat available decreases as carb ice forms
- Use of carb heat causes the mixture to be RICH since hot air is less dense
Organic material made up of many different types of molecules consisting of hydrogen and hydrocarbon atoms that are part of the molecular family known as hydrocarbons.
Petroleum
note: Avgas is a hydrocarbon fuel refined from petroleum
Requirements for Aviation Fuel
- Chemical
- High heat content
- Free from acid and gum causing constituents
- Low freezing point
- High boiling point
- Good vapor pressure (not volatile)
2.Physical
- Free from contaminants
- Easy to filter
- Pumpable at low temperatures
Pressure and Vaporization
- Vapor Pressure
- Measure of rate of vaporization of fuel while under pressure. - Proper Vaporization
- Depends on a chemically correct mixture of fuel and air
being united in a combustion chamber that through compression receives the optimum temperature increase.
- In order to get max power from an engine, we must have the lowest specific fuel consumption from an aircraft engine and the cylinder pressure must be raised as high as possible (Usually done by increasing compression ratio).
- Max compression ratio is limited by the critical pressure of fuel.
- Critical Pressure
- Pressure at which fuel becomes too volatile and explodes rather than burns.
A heavy, oily and poisonous liquid that is usually used to reduce the critical pressure of fuel
Tetraethyl Lead
As a segment of the petroleum industry, the production of aviation fuel makes up less than 1% of the total petroleum production volume.
Grades of Fuel
Fuel Handling
Improper grade of fuel, fuel contamination, and a static electricity generated spark are the 3 main hazards a pilot is presented with when refueling.
- Ensure fire protection equipment is available
- Observe the refueling process to ensure the correct amount and grade of fuel is being added.
- After refueling is completed, wait at least 15 minutes for contamination to settle then drain the tanks.
- Touch metal hose nozzle against metal of the airplane to discharge any static electrical charge.
- Aircraft is properly bonded (grounded) to fuel facility.
- Receive training in refueling procedures before attempting to refuel.
Three Classifications of Contaminants
Solid-dirt, dust, rubber, etc.
Surfactants-byproducts of fuel processing that adhere to other contaminants, which settle to the bottom of the tank as sludge.
Water-results from condensation or faulty seals around cap.
- Common in airplanes stored in a heated hangar.
- As the a/c cruises at altitude, the fuel cools, condensing water vapor.
If improper grade is added
- Bring immediate attention to the mechanic.
- Drain and flush system.
- Perform compression checks if engine has been operated to ensure no internal damage.
three grades of aviation fuel
80 Octane-red
100 Octane-green
100 L/L-blue
All complete electrical circuits consist of 3 elements
- Source of electrical energy-battery or generator.
- A load to use the energy.
- Conductors to join the source to the load.
If there is an interrupted circuit it is said to be an
Open Circuit - no work is performed
Create a path for the electrons to flow from the source, through the load and back to the source.
Conductors
Types of Switches
Toggle-Flipon,flipoff.
Rocker-Master switch.
Precision-Limit switch,stops landing gear motor,etc.
Relay and Solenoid-Used when it is necessary to a circuit carrying a large amount of power from a remote location (starter circuit).
will open the circuit (stopping electron flow) if too much current is passing through them.
Fuses and circuit breakers
Control the flow of current to a component by varying the voltage, which is done by converting electrical energy to heat energy through resistance (like coils of wire or larger wire)
Resistors
Work as a “filter” to allow current to flow one way, but not to return in the opposite direction
Diodes
Used to increase or decrease AC current (change voltage)
Transformer
Stop AC flow and allow DC current to flow and produce magnetic fields (such as in a solenoid)
Inductors
Converts AC current into DC current
Rectifier
Converts DC current into AC current
Inductor
Why to Carry a Battery?
- Engine Starting.
- After starting, alternator/generator will supply power to the system and to recharge the battery.
- Limited operation of equipment without engine running.
- Alternate source of power during engine failure.
Most commonly used storage battery for aircraft.
Wet Cell Battery
- Chemical process that produced energy begins in the plates of the battery.
- The case of the battery is made of high impact plastic
Wet Cell Battery
Measure of a batteries ability to produce a given amount of current for a specified time and is expressed in ampere-hours.
Battery Capacity
Battery capacity may be reduced by the following:
- Battery Temperature-cold temps decrease battery performance.
- Battery State of Charge-a partially discharged battery will exhibit degraded performance.
- Battery Condition-due to age, service history, hard landings, g-forces, etc.
Advantages of Alternators over generators
- Alternators are much lighter.
- Alternators are easier to maintain.
• Brushes wear out faster in generators than alternators because brushes serve different purposes in each of the respective designs.
Disadvantages of Alternators
More susceptible to damage due to heat.
Flow of electrons or the presence of flowing electrons, or the ability of electrons to flow.
Electricity
Smallest particle of matter.
Atom
Unbalanced atom
Ion
Has mass and occupies space
Matter
- Proton - Positively charged ion.
- Neutron - Neutrally charged ion.
- Electron - Negatively charged ion.
- Balanced - Equal number of protons and electrons.
- Ionization - Electron from one atom joins another atom (considered an electric flow process).
Know these
Materials which have loosely held electrons
Conductor
- Electrons can be made to move through a conductive material in response to a force.
- Metals are typical conductors.
Materials that hold their outer electrons more tightly so that electrons cannot flow in response to an electromotive force.
Insulators
- Plastic or Rubber.
The force which causes electrons to Flow
Electromotive Force
When an electron is attracted from the conductor by the positive charge of the source leaving a positive ion.
Electron Flow
- The ion attracts an electron from an adjoining atom.
- The area of negative charge is an area of excessive electrons. The area of strong positive charge is an area with a deficiency of electrons.
- This exchange continues through the conductor until an electron is furnished by the negative terminal of the source to replace the one that was taken by the source (10-4).
- Electron flow creates magnetic and electrical fields.
- The greater the flow, the stronger the magnetic and electrical fields(electrostatic field).
Basic unit of electrical quantity (6.28 billion electrons).
Coulomb
Flow of 1 coulomb past a point in 1 second.
-Measure of the rate of flow of electricity.
Ampere
One amp-rate of electron flow.
Current
Unit of resistance, or opposition to current flow.
Ohm
Measures pressure exerted by electrical source to push one amp through one ohm of resistance.
Volt
Measure of electrical power (746 ____ = 1 HP).
1. One ___ equals the amount of power dissipated when one amp of current flows under the pressure of one volt.
Watts
Opposition to electrical flow, which causes heat (measured in ohms).
Resistance
Rarely serves a purpose and is usually a nuisance.
Static Electricity
- Causes interference with radios and navigation equipment.
- May jump across flight control hinges causing damage.
- Hazardous during fueling.
Body having the property of attracting iron and producing magnetic fields external to itself.
Magnet
Lines of magnetic force, which leave a magnet from right angles to its surface from the North Pole to the South Pole.
Flux
- Maxwell - One line of flux.
- Flux Density - Number of lines of flux for a given unit area.
- Gauss - Represents a density of one maxwell per square cm.
Measure of the ease with which the lines of flux can travel through a medium.
Permeability
Ability of a magnet to remain magnetized.
Retentivity
Each magnet is referred to as a domain or specific point in space.
Domain
Electrons are negative charges of electricity that can be forced through a conductor.
As they travel, lines of magnetic force are produced surrounding the conductor.
These lines are relatively weak, having no polarity.
Electromagnetism
The magnetic field serves no practical purpose surrounding a conductor unless it is wound into the form of a coil.
Coils
- This creates lines of flux, which are concentrated, and the coil attains the characteristics of a magnet.
- The strength of the electromagnet is determined by the number of turns in the coil and the current flowing through it.
Two types used in practical applications.(Electromagnets)
- Fixed Core - Used in such devices as voltage regulators.
- Moveable Core - Also called solenoids and are used for starters and generators/alternators.
SOURCES OF ELECTRICAL ENERGY
- Magnetism
- Chemical
- Thermal
- Pressure
- Light
The current that flows in a circuit is directly proportional to the voltage (pressure) that causes it, and inversely proportional to the resistance (opposition) in the circuit).
Ohm’s Law
ADVANTAGES OF AC OVER DC
- Easier to generate in large quantities.
- Current values and voltages can easily be changed to get the most effective use of electrical energy.
ADVANTAGES OF DC OVER AC
- Electrons flow in one direction only.
Advantages of having a cabin pressurization system
- Allows for flights at higher altitudes without the use of supplemental oxygen.
- Heating, cooling, and ventilation can be more closely controlled.
- Eliminates the need for oxygen mask and allows for long flights at medium altitudes allowing for increased comfort and efficiency.
