the effect of humidity on power _____ as temp _____
decreases; decreases
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humidity effects become inconsequential at _______ altitudes
high
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___ O2 molecules will be present in a cylinder full of ____ air so ____engine power can be expected from _____ air
more; cold; more; cold
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general rule for temp and HP
for each 6 deg C below std, 1% more HP is produced; for each 6 deg C above std, 1% less HP is produced
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if the throttle is fixed in the open position, MAP will vary with the amount of what?
ambient pressure and friction loss in the intake manifold
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if the engine is not running, pressure in the intake manifold (MAP) will be ____ to ambient pressure
equal
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ambient pressure decrease during climb
1 in of Hg per 1000 ft of alt
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critical altitude
alt where the throttle is fully open in order to achieve the desired power setting
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the desired power setting ____ be maintained above critical altitude
cannot
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most normally aspirated reciprocating engines in GA a/c are designed to produce continuous power w/ economical operation and long life if operated at or below what % of their sea level rated power?
75%
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100% power is only available when?
at sea level and full throttle
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for any given % power and RPM, ____ manifold pressure is req’d to achieve the same power setting as altitude increases
less
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most important rule for the pilot to follow with regards to engine operation
keep all operations within the limitations established by the manufacturer
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when reducing power, reduce what first?
MAP
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when increasing power, increase what first?
RPM
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dieseling
engine running without ignition
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keep what high during power changes?
RPM
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superchargers
driven directly from the engine, using some of the power produced by the engine; compress the fuel:air mixture before it is mixed w/ the fuel
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turbochargers
driven by the hot, high-velocity exhaust gasses that are being expelled from the engine
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turbo-supercharger
an engine system that both boots the air pressure before the carburetor and further boots pressure of the fuel:air mixture
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advantages of flying at high altitudes
* fly above icing conditions, turbulence, and high terrain * utilize beneficial winds aloft * enjoy a lower traffic density * better speed
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stage
each increase in the pressure of the air or fuel:air mixture in an induction system
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types of engines that superchargers are found on
high-horsepower radial engines
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main parts of a turbocharger
compressor assembly, exhaust gas turbine assembly, pump and bearing casing
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how turbochargers derive their power
from the energy of engine exhaust gasses directed against some form or turbine
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parts of a compressor assembly
impeller, diffuser, casing
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impeller
gives the air high velocity
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diffuser
direct the airflow and converts the high velocity of the air to high pressure
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casing
where the air enters for the induction system
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exhaust gas turbine assembly parts
turbine (bucket) wheel, nozzle box, butterfly valve (wastegate), and cooling cap
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turbine wheel
driven by exhaust gasses and drives the compressor impeller
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what drives the turbine wheel
exhaust gasses
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nozzle box
collects and directs the exhaust gasses onto the turbine wheel
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wastegate
regulates the amount of exhaust gasses directed to the turbine by the nozzle box; regulates the speed of the rotor
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cooling cap
controls a flow of air for turbine cooling
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manual wastegate control
vernier control in the cockpit connected by cable directly to the wastegate
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automatic wastegate control
uses a pressure controller to control the wastegate
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critical altitude for a given MAP setting is reached when the wastegate is
closed
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further climb past critical altitude will result in what?
a reduction of MAP
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in order to keep MAP from increasing above the desired setting during descent, what must the pilot do? (manual)
open the wastegate
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when the wastegate is fully open, what is used for further MAP control?
the throttle
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deck pressure
pressure between the discharge of the compressor and the engine throttle valve
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ground boosted engine
engine that req’s MAP in excess of sea level pressure to produce its rated power
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what do modern automatic turbocharger systems utilize to regulate the wastegate?
density controller and differential pressure controller
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the position of the wastegate valve is controlled by what?
oil pressure
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when oil pressure is increased, the position of the wastegate valve moves how?
closed
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when oil pressure is decreased, the position of the wastegate valve moves how?
open
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density controller
limits max MAP and prevents overboost by limiting the deck pressure while the a/c is below the turbocharger’s critical altitude
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overboost
excessive MAP
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what control device prevents overboost?
density controller
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what control device reduces bootstrapping?
differential pressure controller
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differential pressure controller
regulates the position of the wastegate valve to maintain a pre-set pressure differential across the throttle and reduces bootstrapping
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bootstrapping
an indication of unregulated power change that results in the continual drift of manifold pressure
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is bootstrapping detrimental to engine life?
no
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overboost
a condition in which the MAP exceeds the limits prescribed for a particular engine; can cause serious damage
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is overboost detrimental for an engine?
yes
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overshoot
rapid movement of the throttle that can cause a certain amount of manifold pressure drift in a turbocharged engine
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is overshoot fatal to an engine?
no
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intercooler
cools the air in turbo-equipped induction systems after compression
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electricity
the flow of electrons
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electron
very small electrically charged particle that exists as a part of every atom
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atom
the smallest particle of any matter that is able to exhibit the properties and characteristics of that matter
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insulators
made of mat’ls which are composed of atoms that are tightly packed so that electrons cannot flow
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conductors
mat’ls with loosely bound electrons so electrons can easily flow through them
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electromotive force
the force which causes electrons to flow
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resistance
opposition to electron flow
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conventional current flow
positive to negative
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electron flow
negative to positive
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current
rate of electron flow
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amp (unit)
measure of electron flow
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voltage
electrical pressure
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volt (unit)
unit of electrical pressure
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two types of electricity
static and current
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purpose of static electricity
rarely serves a useful purpose; more often a nuisance
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static wicks
provide sharp points from which static charges are dissipated into the air before they can build up to a high potential on the control sfc
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bonding straps
provide a low-resistance path between the control sfc and the a/c structure to prevent the buildup of a static charge on the control sfc
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permeability
the measure of ease with which the lines of flux can travel through a mat’l or medium
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two types of electromagnets
those with fixed cores and those with movable cores (solenoids and relays)
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solenoids
electromagnets with movable cores
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thermocouple
device for measuring temperature, consisting of two wires of different metals connected at two points
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electrons will flow in a thermocouple made of dissimilar metals when
there is a temperature difference between the two junctions
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piezoelectric
mat’l that when bent or deformed by a mechanical force, has an excess of electrons accumulate on one surface, leaving the opposite surface with a deficiency
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piezoelectric effect
relating to or involving electric polarization resulting from the application of mechanical stress
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Ohm’s Law
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
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which type of current is easier to generate in large quantities needed for homes and large transport a/c?
AC current
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battery
a device composed of one or more cells in which chemical energy is converted into electric energy
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parts of an aircraft electrical system
the electrical energy source, the circuit, and the active component
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most commonly used storage battery for a/c
lead-acid battery
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capacity
measure of a battery’s ability to produce a given amount of current for a specified time
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ampere-hour
the amount of electricity that is put into/taken from a battery when a current of one ampere flows for one hour; expresses battery capacity
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rated capacity
the battery’s ability to perform when it is new
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actual battery capacity depends on
battery temperature, battery state of charge, and battery condition
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battery condition is degraded by
age, service history, g forces applied
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advantages of NiCd batteries
ability to accept high charge rates, discharge at equally high rates w/o voltage drop associated w/ lead-acid batteries, lower susceptibility to very low temps than lead-acid batteries
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disadvantages of NiCd batteries
more expensive, req's more/more expensive maintenance, develops “memory” that must be erased, subject to thermal runaway, req’d more sophisticated monitoring systems
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types of a/c NiCd batteries are used on
turbine engine a/c
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thermal runaway
uncontrollable, self-heating state; battery accepts all of the charging current the source is capable of producing