AFC-Lesson 2-AircraftSystems · 2018-03-22 · Lesson 2 Aircraft Systems ... Magnetic Compass...
Transcript of AFC-Lesson 2-AircraftSystems · 2018-03-22 · Lesson 2 Aircraft Systems ... Magnetic Compass...
3/22/2018
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Sport / Private Ground School
Lesson 2
Aircraft Systems
Fuselage
• Body of Aircraft
• Cabin and Flight Deck
• Seats / Baggage area
2
• Engine and Propeller– Engine produces power
– Propeller produces thrust
• Generates electrical power
• Environmental system
• Other Accessories
Powerplant
3
Wings and Landing Gear
• Wings
– Monoplane or biplane
– High and low wing
• Landing Gear
– Tail Wheel or tricycle
– Fixed or retractable
4
Control Surfaces
• Primary
– Ailerons ‐ roll
– Elevator ‐ pitch
– Rudder ‐ yaw
• Secondary
– Flaps
– Trim tabs
5
Empennage
• Horizontal Stabilizer
– Elevator ‐ pitch
• Vertical Stabilizer
– Rudder ‐ yaw
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Flight Display (Instruments)
• Eyes outside about 90% of the time (VFR)
– See and Avoid Traffic
– Scan instruments briefly
– “6 pack”• Airspeed Indicator
• Attitude Indicator
• Altimeter
• Turn Coordinator
• Heading Indicator
• Vertical Speed Indicator
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Magnetic Compass
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• Bar magnet with two poles automatically aligns with the earth’s magnetic fields
• No dependency on electrical or vacuum system
Magnetic Compass
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• Variation – angular difference between true and magnetic
• Deviation – compass error caused by magnetic fields of the airplane and its electrical electronic equipment
• Magnetic dip – tendency for the magnet in the compass to be pulled downward, especially near poles. To counteract dip, a weight is placed opposite the magnet in the compass, but that contributes to some errors.
Magnetic Compass Errors
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• Acceleration error: – Intertia causes the weight on the south end of the compass to move slightly ahead when aircraft decelerates or behind when accelerating
– Acceleration error is more pronounced as you move closer to due east or west.
– ANDS (Accelerate North, Decelerate South)
• Turning error– Most pronounced when turning from headings of north or south “North lags, south leads”
– UNOS (Undershoot North,Overshoot South)
Coping with Compass Error
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• Heading indicator used as primary heading reference
• Compass only accurate when flying in smooth air, in straight‐and‐level, unaccelerated flight
Gyroscopic Instruments
1) Attitude Indicator (Artificial Horizon)
2) Heading Indicator (Directional Gyro)
3) Turn Coordinator
• Power by either vacuum system or electrical system
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Rigidity in Space / Precession
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Heading Indicator
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• Easier to read than compass
– North: 360 degrees
– East: 90 degrees
– South: 180 degrees
– West: 270 degrees
• Expressing: 10 degrees would be “zero one zero degrees”
• Due to precession readjust DG every 15 minutes to compass
Attitude Indicator
• Depicts both pitch and bank information
• Miniature airplane is adjustable and should be set to match the level flight indication of the horizon bar
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Turn Coordinator
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• Gyroscopic part – indicates direction and rate of turn, used for establishing “Standard rate” or “Two minute” turn (3˚per second)
• Inclinometer – shows coordination (proper use of rudder).
• “Step on the ball” – apply rudder pressure on the side to which the ball is deflected
Turn Coordinator
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Pitot‐Static Instruments
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• Rely on air pressure differences to measure speed and altitude
• Airspeed indicator, altimeter, and VSI use static air pressure
• Airspeed indicator also uses ram air pressure. Airspeed is determined by comparing ram air pressure with static pressure
Pitot‐Static Blockages
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• Clogged pitot only affects airspeed– airspeed will decrease to zero as gauge detects no difference between pitot and static pressure
• Clogged static affects airspeed, altimeter, VSI– Airspeed will read slower if airplane is operated above altitude that port froze and visa‐versa
– Altimeter will be frozen
– VSI will read “zero”
Airspeed Indicator
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• Pitot tube measures dynamic pressure to show speed
• Divided into airspeed ranges
– White Range: Flap Operation Speeds
– Green Range: Normal Operating Speeds
– Yellow Range: Caution speeds
– Red Line (Higher speed): Never Exceed Speed
– Red Line (Lower speed): Low Speed Awareness
Airspeed Indicator
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Airspeeds (V Speeds)
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• Vso – Stall Speed Landing Configuration• Vs – Stall Speed Clean Configuration • Vr – Rotation Speed• Vg – Best Glide Speed• Vx – Best Angle of Climb• Vy – Best Rate of Climb• Va – Maneuvering Speed• Vfe – Max Flap Extend Speed• Vno – Max Structural Cruising Speed• Vne – Never Exceed Speed
Airspeeds
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• Indicated Airspeed IAS – Direct reading from the airspeed indicator, uncorrected for atmospheric, instrument, or installation errors
• Calibrated Airspeed CAS – Indicated airspeed corrected for installation and position error
• True Airspeed TAS – Calibrated airspeed corrected for altitude and non‐standard temperature
• Groundspeed GS – True airspeed adjusted for the wind
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Airspeed and Altitude
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• Increase in altitude results in increase in true airspeed for the same indicated airspeed
• True airspeed increases for same IAS as altitude increases (Roughly 2% per 1,000’). – 100kts IAS at sea level = 100kts TAS. – 100kts IAS at 10,000’ = 120kts TAS
• Always use indicated airspeed for takeoff / landing / stalls / maneuvers
Altimeter
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• Pressure Sensitive – Measures outside static air pressure
• Set barometric pressure in Kollsman window
• Set altitude to field elevation
when altimeter setting is
unavailable
Altimeter
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• Longest pointer shows 100s’
• Mid‐sized pointer shows 1000s’
• Shortest pointer shows 10,000s’
• Increasing altimeter setting will increase indicated altitude (1000 feet for every 1 inch of Hg)
10,500’
Reading the Altimeter
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Reading the Altimeter
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• Indicated Altitude: Read from altimeter
• Pressure Altitude: Height above the standard datum plane. Theoretical level where weight of the atmosphere is 29.92” Hg.– What the altimeter reads when set to 29.92
• Density Altitude: Pressure Altitude corrected for non‐standard temperature. Density Altitude increases as ambient air temperature increases or pressure decreases
Reading the Altimeter
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• True Altitude: Height above Mean Sea Level (MSL)
• Absolute Altitude: Height Above Ground Level (AGL)
• True = Pressure = Indicated when standard atmospheric conditions exist
• True altitude = field elevation when altimeter is set to local pressure setting
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Altimeter Errors
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• Accuracy depends on how much pressure, temp, and lapse rates deviate from standard, and how recently you reset your altimeter
• Most common error results from failure to reset altimeter: If altimeter changes from 30.00 to 29.50, you’ll be off by 500’
• From high to low… look out below
• From hot to cold… look out below
Vertical Speed Indicator
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• Trend information – Indication of increase or decrease in aircraft rate of climb or descent
• Rate information displayed in feet per minute
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Engine and Propeller
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• Powerplant – combination of engine and propeller
– Work together to produce thrust
– Drive various other aircraft systems
Reciprocating Engines
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• Convert chemical energy into mechanical energy
• Characteristics:
– Cylinder arrangement
• Radial, horizontally opposed, rotary
– Number of cylinders
• 4, 6, or more
– Method of cooling
• Liquid or air
– Naturally aspirated or turbo/ super
charged
Induction System
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• Brings in outside air to mix with fuel for combustion
– Volume of air controlled by throttle
– Fuel by the mixture
• Mixing of fuel and air to engine– Carburetor
– Fuel Injection
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Carbureted Engines
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• Outside air flows through an air filter
• Air passes through a venturi
– Air speeds up, pressure lowers
• Pressure difference draws fuel from the float chamber to mix with air
• Throttle controls volume of air
– therefore amount of vaporized fuel
that will enter cylinders
Carburetor Icing
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• Ice can form in venturi or around throttle valve
– Temperature drop due to fuel vaporization
• Temperature drops as much as 60‐70ºF (15‐21ºC)
• Favorable conditions for carburetor icing are
– High humidity
– Temperatures between 20ºF to 70ºF (‐7ºC to 21ºC)
– POSSIBLE AT ANY TEMPERATURE OR HUMIDITY
Carburetor Icing
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Indications of Carburetor Icing
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• In a fixed pitch propeller airplane:
– Loss of RPM
• The ice will accumulate and block the airflow, just as the throttle valve does when it closes causing a reduction in RPM
• In a constant speed propeller airplane:
– Loss in manifold pressure
Carburetor Heat
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• When the carburetor heat is turned on– Air is ducted from around the hot exhaust muffler
– The warmer air flows into the carburetor and melts the ice
– The melting ice produces an additional loss of RPM and possible engine roughness
– Symptoms should clear within 30 seconds
– The RPM will gradually increase once the ice is melted
Carburetor Heat
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• Turn on carburetor heat without delay– Carb heat requires exhaust heat
– A dead engine will cool quickly, and may not leave enough residual heat
• Should be applied with reduced power settings as a preventative measure
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Fuel‐Injected Engines
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• A fuel‐injection system consists of:
– Engine‐driven fuel pump• Provides pressurized fuel from the fuel tank to the fuel/air control unit once engine is running
– Auxiliary (electrically‐driven) fuel pump
• Provides pressurized fuel to the fuel/air control for starting or emergency use
Fuel‐Injected Engines
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– A fuel/air control unit
• Meters fuel based on the mixture setting (more throttle = more fuel and air)
– A fuel distributor
• To distribute fuel to the individual fuel discharge nozzles located at each cylinder
– Fuel discharge nozzles
• To inject the fuel directly into each cylinder
– Fuel pressure/flow indicator
• To tell you how much fuel is flowing to the engine
Fuel‐Injected Engines
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Fuel‐Injected Engines
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• All aircraft are susceptible to impact icing of intake air– Automatic or manually actuated
alternate air source
– Carburetor heat serves as alternate air on carbureted aircraft
Fuel‐Injected Engines
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• Advantages:
– Better fuel economy
• Better fuel distribution
• More precise control of mixture
– Faster throttle response
– Easier cold weather starts
– No carburetor ice
• Disadvantages
– Difficulty starting a hot engine
– Vapor lock on hot days
– Problems with engine restart when engine fails due to fuel starvation
• Cylinders
• Pistons
• Intake Valves
• Exhaust Valves
• Spark Plugs
• Crankcase
• Crankshaft
• Connecting Rod
Basic Engine Parts
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The 4‐Stroke Engine
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• Induction Stroke
• Compression Stroke
• Power Stroke
• Exhaust Stroke
Operating the Engine
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• Engine needs:
– Fuel, air, and spark
– Oil for lubrication, cooling and cleaning
• You control:
– The amount of fuel that is mixed with air
– This is referred to as the “mixture”
• Desired air‐to‐fuel ratio (by weight) is:
– 15 parts air to 1 part avgas (15:1)
Adjusting the Mixture
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• Air decreases in density with increase in altitude– A given volume of air will have fewer molecules and therefore less mass
– A proper ratio of air mass to fuel mass must be maintained• Compensation for changing air density is controlled by the mixture
– Adjust for best economy or
best power
Operating the Engine
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• If the mixture has:– Too little fuel for the amount of air = too “lean”
– Too much fuel for the amount of air = too “rich”
• If the mixture is too lean or too rich– The fuel mixture will not burn properly– The engine won’t run smoothly
– Overly rich mixture will cause carbon build‐up on the sparkplugs
Leaning the mixture
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• Lean the mixture when
– Using 75% power or less
– Above 3000ft MSL
• Even when at full throttle and/or climbing
• Anytime above 3000ft MSL, aircraft will be less than 75% power
Leaning the mixture
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• To lean the mixture– Use an EGT (exhaust gas temperature)
– G1000 can use “lean assist”
– Or lean using RPM method
• Full‐rich mixture should be used– At high power settings below 3000ft MSL
• Takeoffs and landings
– Before landing in case of go around
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Engine Temperature
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• Primary method of cooling the engine is airflow (cooling fins, baffles, cowl flaps control cooling)
• Air enters the inlets in the nose– Directed around cylinders by the baffles– Leaves through the bottom of the cowling– Carries away heat
• Fuel/air mixture directly affects the engine temperature– The richer the mixture ‐ the lower the engine temperature, excess fuel carries heat away
– The more lean the mixture ‐ The higher the engine temperature
Cooling System
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• If too hot:– Reduce the rate of climb/ Increase airspeed
– Reduce power– Enrich mixture
• Indicated by:– Oil Temp– Cylinder Head Temp– Exhaust Gas Temp
High Engine Temperature
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• Loss of power
• Excessive oil consumption
• Engine Damage
• Detonation and/ or pre‐ignition
Detonation
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• Fuel/air mixture explodes within combustion chamber instead of burning smoothly
– Excessive temperature or cylinder/piston damage can occur
Detonation
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• Can be caused by:
– Too low of a fuel grade (most airplanes use 100LL or 100 AVGAS)
– Operating at too high of a power setting with excessively lean mixture
– Extended ground operations where the cylinder cooling is reduced
Pre‐Ignition
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• Occurs when fuel/air mixture in the cylinder ignites too soon
– Hot spots on the piston, cylinder, or valves
– Causes a loss of power
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Fuel System
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• Two main types:
– Gravity feed
– Fuel‐pump systems
Fuel System
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• Fuel‐pump systems
– Use electric and engine‐driven fuel pumps
– Common in low‐wing airplanes
Fuel Pump
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• Fuel pump failure detected by fuel flow reduction– Just prior to power loss
• Auxiliary fuel pump used in the event of engine‐driven pump failure
• Aux fuel pump used for:– Starting engine
– Purge vapor from fuel‐injection lines
– Emergencies
Fuel Tanks
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• Each fuel tank has a vent
– Built into the fuel cap
– External fuel vent
Fuel Strainers, Sumps and Drains
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• Drains in the low points of fuel system (C172S)
– Wings
– Belly
Fuel Sample
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• Check fuel sample for:
– Proper smell
– Proper color
– Water free
– Free of contamination
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Fuel Selector
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• Control fuel flow from individual tanks
– Keep tanks balanced
Fuel Shutoff Valve
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• Cuts fuel in emergency
• Used to stop or prevent fire
• Push in fully before takeoff
Fuel Quantity
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• Fuel Gauges only must be accurate when at zero in level attitude
– Check fuel tanks visually before flight
– Perform calculations
• Fuel quantity indicators will not work under electrical failure (with electrically operated gauges)
Airplane Oil
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• Oil protects engine’s internal parts
– Lubricates, cleans, and cools engine
– Check oil pressure immediately after engine start
– Monitor engine temp and pressure throughout flight
Airplane Oil
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• Dry‐sump – oil stored in separate tank and circulated w/pump• Wet‐sump – oil kept in a sump which is an integral part of the
engine
• Oil pressure:– Too low – oil pump not putting out enough pressure to circulate
oil– Too high – could indicate clogged line– Immediately check after starting engine
• Oil temperature:– Too high – could indicate plugged oil line, low quantity, or
defective gauge– Rotax recommends getting oil to 190°F at some point during each
flight to evaporate any water in the oil
Ignition System
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• Airplanes have dual ignition system– Two magnetos, L and R
– Two sets of ignition wires
– Two spark plugs per cylinder
• Duplication allows for:– Redundancy
– Improved engine performance
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Magnetos
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• Uses permanent magnets to generate an electrical current – independent of electrical system
• Directly connected to engine
• Provides electricity for the spark plugs
Ignition Switch
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• Switch has 2 purposes– Sends power to the starter motor– Turns the magnetos on and off
• Turning the ignition switch to the OFF position– Grounds, or short circuits, both magnetos
– Electricity goes through a wire called the p‐lead (primary lead) to the ground
– Referred to as grounding
Ignition Switch
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• Turning the ignition switch to the L (Left) Position– Deactivates right magneto, and
– The engine will only run off of the left magneto
• And vice versa
• Magnetos will not quit after electrical failure
Magneto Check
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• You should see a drop in RPM when engine is running on one magneto
Magneto Safety
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• Never leave the keys in the aircraft ignition unless you are starting the airplane
– Engine can start if key is not at the OFF position and propeller is moved
Propeller
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• Engine power is converted to thrust via the propeller– Propeller may be connected directly to
the crankshaft
– Turns at same speed as the engine
OR
– Propeller may be slowed down by system of gears
– Measured as revolutions per minute (RPM)
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Propeller
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• Propellers are twisted
– Greatest pitch angle at the hub
– Smallest pitch angle at the tip
• Uniform thrust is produced along the length of the blade
Fixed‐Pitch Propeller
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• The pitch, or blade angle, is set at the factory
– Determines how much of a “bite” of air the propeller takes
• Large blade angle is good for cruise
• Small blade angle is good for climb
• Most aircraft manufacturers choose a compromise
Adjustable‐Pitch Propeller
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• Most common type is a “constant speed propeller”
– A propeller governor will use oil pressure to adjust the propeller blade angle to maintain constant RPM
Constant Speed Propeller
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• Throttle controls engine power output– Indicated on manifold pressure
gauge
• Propeller control is used to select RPM
• Use acceptable manifold pressure (throttle) setting and RPM (prop) combinations according to POH
Hydraulic system
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• Brake system uses hydraulic fluid
– Check for leaks
– Fluid is red
– Pedal feel
• Hydraulically actuated landing gear
Electrical System
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• Alternator
• Battery
• Master switch
• Circuit breakers
• 28 volt or 14 volt systems
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Alternator
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• Provides electrical power to the airplane
• Charges battery
Battery
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• Used to start engine
• Provide electrical power when engine is off
• Power reserve in case of alternator failure
Master Switch
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• Electrical system “on/off” switch
– Switch switch
• Battery switch
• Alternator switch
Circuit Breakers
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• Modern airplanes uses circuit breakers, not fuses
– Prevents circuit overloads
• If circuit breaker pops out, reset circuit breaker one time if no smoke exists
• If circuit breaker pops out again, get a mechanic
TEST TIME!
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