Airframe, Engine

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Airframe, Engine Systems
The Things That Get You Going
Written for the Notre Dame Pilot Initiative By
the Pilots of the University of Notre Dame
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Roadmap

• Airplane Components
• Engine
• Ignition System
• Carburetor vs. Fuel Injection
• Fuel System
• Oil System
• Cooling System
• Electrical System
• Miscellaneous Systems
• Propellers
• Jet Engines

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Airplane Components

• Fuselage
• Body of the airplane to which the wings,
  empennage, engine, and landing gear are attached
• Wings
• Spars
• Run perpendicular to the fuselage
• Ribs
• Run parallel to the fuselage

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Spars Ribs (mmm)
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Airplane Components

• Empennage
• Tail section of the airplane
• Vertical Horizontal Stabilizers
• Control Surfaces
• Elevator
• Controls pitch
• Rudder
• Controls yaw
• Ailerons
• Control roll

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Airplane Exteriors C172
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Airplane Exteriors A-10
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Airplane Exteriors B727
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Airplane Exteriors B727
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Airplane Exteriors B727
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Airplane Components

• Landing Gear
• Tailwheel (Conventional)
• Tri-cycle
• Brakes

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Ground Steering?
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Engine

• Engine Types
• Reciprocating (piston)
• In-Line
• Radial
• Horizontally Opposed
• Turboprop
• Turbojet
• Turbofan

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Horizontally Opposed Engines
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Reciprocating Engines

• Horizontally Opposed Piston
• 4-stroke operating cycle

Four Stroke Cycle
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Ignition System

• Provides the spark that ignites the fuel/air
  mixture in the cylinders
• Each magneto is connected to one of the two spark
  plugs in each cylinder
• Increased safety
• Improved engine performance
• Magneto uses a permanent magnet to generate an
  electrical current independent of aircrafts
  electrical system

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Carburetor

• Mixes incoming air
• with fuel
• Delivers to combustion chamber
• Air enters thru venturi
• Increases velocity
• and decreases
• pressure due to
• change in area

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Carburetor Icing Carb Heat

• Loss of RPM (fixed pitch) may indicate carburetor
  icing
• Use of carburetor heat decreases energy
  performance

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Fuel Injection
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Mixture

• At higher altitudes, the fuel/air mixture must be
  leaned to decrease the fuel flow to compensate
  for the decreased air density
• If you descend to lower altitude without
  enriching mixture, mixture will become leaner
  (could starve engine)

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Fuel System

• Carbureted or Fuel-Injected
• Gravity-fed and/or pump
• Engine driven pump
• Auxiliary boost pump
• Fuel tanks almost always in wings
• Selector valve
• LEFT, BOTH, RIGHT, OFF
• Mixture Control

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Fuel System

• Fuel Types
• Fuel Tanks

Grade Color
80/87 Red
100LL Blue
100/130 Green
Jet-A Clear
TOTAL USABLE FUEL TOTAL UNUSABLE FUEL TOTAL FUEL VOLUME
53 3 56
1997 Cessna 172R
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Refueling

• Park Ground Refuel
• Fuel Vents
• Using lower grade fuel than specified can cause
  cylinder head and engine temperatures to exceed
  normal operating limits. Use higher grade if not
  sure.

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Fuel Checking

• Always check your fuel before using it

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Oil System

• Why oil?
• Friction
• Cooling
• Seal
• Contaminants
• Oil Temperature
• Incorrect type/quantity
• Oil Pressure
• Insufficient quantity, leak, pump

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Engine Temperature

• Excessively high engine temp will cause loss of
  power, high oil consumption and wear on inside of
  engine
• Engine is cooled (in part) by circulating oil
  through system to reduce friction and absorb heat
  from internal engine parts
• Engine oil and cylinder head temps can be too
  high
• Operating with too much power
• Climbing too steeply in hot weather
• Using low-octane fuel
• Mixture too lean
• Oil level too low

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Cooling Exhaust Systems

• Cooling
• Intense heat caused by combustion
• Cowl flaps allow larger amount of ram air to
  escape from engine compartment
• Engine temp can be reduced by enriching the
  mixture, reducing rate of climb, increasing
  airspeed or reducing power
• Exhaust
• Vent burned gases thru muffler
• Provide heat for cabin from metal shrouds around
  muffler
• Defrost the windscreen
• Firewall
• Separates cockpit from engine

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Abnormal Combustion

• Detonation occurs when fuel/air mixture explodes
  instead of burning evenly
• Caused by low octane fuel
• Leads to engine wear and high operating temp
• Pre-ignition is the uncontrolled firing of the
  fuel/air mixture before the normal spark ignition

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Electrical System

• Direct Current
• Battery
• Provides the initial electrical power to start
  engine
• Provides emergency electrical power
• Lead-acid, 12 or 24 volts
• Alternator
• Initially produces alternating current (AC)
• Converts to direct current (DC) for use
• 14 or 28 volts

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Ammeter

• Left-Zero Ammeter
• Alternator ? Ammeter ? Bus Bar ? Battery
• Center-Aero Ammeter
• Alternator ? Bus Bar ? Ammeter ? Battery

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Electrical System Schematic Example
C-182 Alternator
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Miscellaneous Systems

• Stall Warning System
• Static Dischargers
• Fuel Dumping

Fuel Dump Nozzle and Static Dischargers
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Propellers

• Fixed-pitch
• Blade angle pre-selected by manufacturer for
  primary purpose of aircraft
• Constant Speed
• Variable pitch
• Maximizes efficiency at selected rpm

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How to Use a Constant Speed Propeller

• Permits the pilot to select the blade angle for
  the most efficient performance
• Throttle controls power output as registered on
  the manifold pressure gauge, and the propeller
  control regulates engine RPM
• Avoid high MP with low RPM
• When increasing throttle, increase RPM first
• When decreasing throttle, decrease throttle first

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How Constant Speed Propellers Work

• Governor regulates RPM
• Oil pressure regulates angle of blades
• Multiengine
• Increasing RPM Decreasing blade angle
• Decreasing blade angle result of oil being forced
  INTO propeller hub
• Single Engine (generally)
• Increasing RPM Decreasing blade angle
• Decreasing blade angle result of oil being forced
  OUT OF propeller hub
• Why the difference?
• A wind milling propeller creates a lot of drag
• In a multiengine, if we lose one engine, we want
  that propeller to feather (line up directly into
  wind)
• In a single engine, if we lose the engine, we
  want that propeller to windmill as we attempt to
  restart

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How Constant Speed Propellers Work
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Propellers
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Types of Jet Engines
Turboprops
Turbojets
Turbofans
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Turbofan Example
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Turbofan Example

• Suck, Squeeze, Bang, Blow

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Contrails Condensation Trails

• Hot, humid air from jet exhaust mixes with
  environmental air of low vapor pressure and low
  temp
• Contrail becomes visible if condensation (gas to
  liquid) occurs
• Air temp at high altitude is very cold (see lapse
  rate). Only a small amount of liquid is necessary
  for condensation to occur. And, water is a normal
  jet engine byproduct

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Contrails Condensation Trails
Contrails last longer on humid days. If air is
too dry, no contrail will form.
Distrail formed by warm jet engine exhaust
settling down through cloud layer