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Cessna 172N Overview

Structure​

  • Semi-monocoque
  • Thru-spar construction
  • Nose landing gear
    • Oil/air strut, connected directly through the firewall
  • Main landing gear
    • Spring steel strut, very robust
    • Hydraulic disc braking system
      • Hydraulic lines have blue fittings
  • Four seats
    • Separate front seats, combined rear seat
    • Shoulder harnesses and lap belts on front seats
  • Two doors
  • Windows, both openable on some models
    • Max window speed is Vne

Flight Controls​

  • Elevator
    • Cable-actuated
  • Elevator trim
    • Single trim tab on one of the elevators
  • Ailerons:
    • Frise-type ailerons, helps with adverse yaw
  • Rudder
    • Rudder pedals
    • Cable actuated
    • Single manual rudder trim tab
  • Nose wheel
    • Push-pull rods for ground steering
  • Differential hydraulic brakes
    • Rudder with toe brakes
  • Flaps:
    • Slotted flaps (Cessna calls them slotted-types flaps)
  • Control lock
    • Simple pin
    • Rudder control lock also available

Powerplant​

  • Lycoming O-320, 160hp at 2700 RPM
  • Horizontally-opposed, air-cooled, 4-cylinder engine
    • Spinner is designed to direct airflow into the engine baffles
  • Engine-driven magnetos
    • Self-contained magnets that generate electrical sparks
  • Induction system
    • Air filter below the propeller, entire source of air for the engine
  • Exhaust manifold which vents exhaust overboard
    • The heater is a shroud around this exhaust manifold
  • Updraft-type carburetor with a venturi
  • Primer used for cold-starting
  • Engine controls
    • Carburetor heat for carburetor ice
    • Throttle: controls airflow to the butterfly valve in the carburetor
    • Mixture: red handle, controls fuel/air mixture
    • Ignition switch
  • Engine instrumentation
    • Fuel gauges which are electric
    • Oil temperature, oil pressure gauges
    • Tachometer
  • Oil system
    • Wet sump oil system, all the oil is contained in the bottom part of the engine
    • 6 quart capacity
    • Use correct SAE viscosity temperature of oil
  • Propeller
    • Fixed-pitch, two blade

Fuel system​

  • Two tanks within each wing
  • Fuel caps, one is vented one is not
  • Fuel vent on left tank below the wing
  • Tube between both tanks to allow venting between tanks
  • Fuel sumps on both tanks
  • Gravity-fed system into a fuel selector
  • Fuel strainer on the gascolator at the lower point

Brake System​

  • Red hydraulic fluid which closes disc calipers on the rotors
  • Parking brake, don't trust them
    • If temperature increases while it's set can cause too much pressure to build in the system

Electrical System​

172N Electrical Diagram

  • Components
    • 28V DC alternator (60A, continuous output)
      • Higher voltage than the battery so it will charge the battery
    • 24V, 14 A/h battery
      • Without the alternator, the voltage should read 24V
      • Provides 14 amps for 1 hour
    • Bi-direction ammeter
    • Over-voltage protection
    • Hobbs meter: comes on with battery but is activated by an oil pressure transducer

Vacuum System​

  • Drive gyros to AI and DG
  • Suction 4.2-5.5 PSI, suction gauge

Stall Warning System​

  • Mechanical reed that plumbs the sound into the cockpit
  • Activated by low pressure at a certain threshold, given by a certain AoA

Static Wicks​

  • If you're going fast enough in precipitation you can build up static electricity on the control surfaces
  • Static wicks are trailing wires that hang off the back which transmit the static off the back