How a Small Airplane Works - Cessna 172

Introduction

• Cessna 172: Most popular single-engine aircraft
• Components: Fuselage, wings, empennage, landing gear, power plant

Internal Structure

Fuselage

• Made of aluminum formers, bulkheads, longerons, and stringers

Wings

• Ribs: Provide airfoil shape
• Spars: Run entire length, provide strength
• Stringers: Support shape
• Airfoil shape: Critical for lift and minimal drag
• Covered with aluminum sheets riveted to skeleton (airframe)
• Primed with zinc chromate or zinc phosphate for corrosion protection

Wing Struts

• Reinforce wing-fuselage joint
• Attach to main spar and lower front fuselage
• Carry-through channels to join wings in high-wing configurations

Static Wicks

• Discharge static electricity to prevent radio interference

Power Plant

• Includes engine, propeller, and components
• Example engine: Lycoming IO-360 (4-cylinder, horizontally opposed piston engine, 225 HP)

Engine Functions

• Rotates propeller for thrust
• Moves alternator for electricity
• Vacuum pump for gyroscopic instruments
• Heats cockpit
• 4-stroke engine cycle (intake, compression, combustion, exhaust)

Propeller

• Directly attached to crankshaft (direct drive)
• Fixed-pitch

Cooling and Fuel Systems

• Air-cooled engine
• Fuel delivery: Carburetor vs. fuel injection
• Example: Lycoming IO-360 uses fuel injection

Fuel Injection

• Electronic sensors for precise fuel-air mix
• Spark plugs and magnetos for ignition

Fuel System

• Fuel tanks: Located in wings (28 gallons per tank, 56 gallons total, 53 gallons usable)
• Fuel grade: 100LL (blue color)
• Fuel selector switch in cockpit
• Auxiliary fuel pump for startup
• Fuel filter: Gascolator
• Engine-driven fuel pump
• Fuel vent for pressure stabilization

Control Surfaces

Primary Control Surfaces

• Ailerons

  • On wings, control roll
  • Opposite movement for left/right turn

• Elevator

  • On horizontal stabilizer, controls pitch
  • Push/pull yoke for up/down
  • Trim tab for fine-tuning

• Rudder

  • On vertical stabilizer, controls yaw
  • Controlled with pedals

Secondary Control Surfaces

• Flaps
  • Increase lift at lower speeds
  • Electrically actuated, controlled by lever
  • Different angles: 10, 20, 30 degrees

Landing Gear

• Tricycle type, fixed
• Main legs: Aerodynamic fairings, some removed for easier maintenance
• Front wheel: Steerable, shock absorber, shimmy damper
• Back wheels: Brakes for control during landing

Cockpit

• Pilot seat: Front left
• Capacity: Up to 4 adults (depending on fuel/baggage/weather)
• Maximum takeoff weight: 2,550 lb
• Useful load: 878 lb
• Instrument panel: Primary flight display (PFD) and multifunction display (MFD), Garmin G1000 avionics

Redundancy

• Analog gauges: Airspeed, attitude, altimeter
• Pitot tube: Measures airspeed
• Static port: Measures altitude and vertical speed
• Attitude indicator: Real-time bank and pitch

Lights and Electrical System

• Battery: Main power source when engine off
• Starter: Rotates engine initially
• Alternator: Powers aircraft when engine running
• Lighting: Beacon, strobe, navigation, landing, and taxi lights

Light Types

• Beacon: Red, alerts ground crew
• Strobe: Anti-collision, white
• Navigation: Position lights (red on left, green on right, white at back)
• Landing/Taxi: Illuminate takeoff/landing path

Additional Resources

• Pilot Institute: Deep dive classes, free courses, VR experience

Conclusion

• Cessna 172: Detailed overview of structure, systems, and controls
• Encourage comments and suggestions for future content