Aircraft Systems and Components: Structural, Power, and Control Systems

Aircraft System of Systems

The concept that an airplane is made up of multiple interdependent systems working together

Airframe

The structural components of an aircraft including fuselage, wings, stabilizers, landing gear

Powerplant

Engine and propeller that produce thrust and power other systems

Avionics

Electronic systems used for navigation, communication, and flight management

Hydraulic System

Uses incompressible fluid to transmit force

Flight Controls

Systems that control aircraft attitude and direction

Fuselage

The main body of the aircraft that holds passengers and cargo

Truss Fuselage

Lightweight fuselage with internal framework but less strength

Monocoque Fuselage

Structure where the skin carries most of the load

Semi

Monocoque Fuselage - Most common design using skin plus internal structure

Cantilever Wing

Wing without external bracing; reduces drag

Wing Spar

Main load-bearing structure of the wing

Wing Ribs

Shape the airfoil of the wing

Stringers

Longitudinal structural supports

Composite Materials

Lighter, stronger, corrosion-resistant materials used in modern aircraft

Pascal's Law

Pressure applied to a confined fluid is transmitted equally in all directions

Hydraulic Advantage

Allows force multiplication by increasing area

Hydraulic Reservoir

Stores hydraulic fluid

Hydraulic Pump

Moves fluid through the system

Actuator

Converts hydraulic pressure into mechanical motion

Relief Valve

Prevents over-pressurization

Reciprocating Engine

Piston engine commonly used in small aircraft

Radial Engine

Cylinders arranged in a circle; rugged and powerful

Horizontally Opposed Engine

Low weight, reliable, most common piston aircraft engine

Four

Stroke Cycle - Intake, compression, power, exhaust

Carburetor

Mixes fuel and air before combustion

Fuel Injection

Directly injects fuel into engine cylinders

Propeller

A rotating airfoil that converts engine power into thrust

Tractor Propeller

Propeller mounted in front of the engine

Pusher Propeller

Propeller mounted behind the engine

Propeller Tip Speed

Tip moves faster than the root

Turbojet

Produces thrust only from exhaust

Turbofan

Produces thrust from exhaust and fan

Turboprop

Turbine engine that drives a propeller

Turboshaft

Turbine engine that drives a shaft

Bleed Air

High-pressure air tapped from the engine compressor

Primary Flight Controls

Ailerons, elevator, and rudder

Ailerons

Control roll around the longitudinal axis

Elevator

Controls pitch around the lateral axis

Rudder

Controls yaw around the vertical axis

Secondary Flight Controls

Flaps, slats, spoilers, trim

Fuel System Purpose

Stores and delivers fuel to the engine under all conditions

AvGas

Aviation gasoline used in piston aircraft; dyed blue

Jet A Fuel

Refined kerosene used in turbine aircraft

Fuel Shutoff Valve

Allows fuel flow to be stopped in emergencies

Fuel Vent

Prevents vacuum formation in fuel tanks

Pressurization

Pumping high-pressure air into the cabin to sustain oxygen levels

Outflow Valve

Controls cabin pressure by regulating escaping air

Cabin Safety Valves

Prevent cabin from exploding or imploding

Gaspers

Adjustable air vents above passenger seats

Pitot

Static System - Provides airspeed, altitude, and vertical speed information

Altimeter

Measures altitude using static pressure

Vertical Speed Indicator

Indicates rate of climb or descent

Airspeed Indicator

Uses pitot and static pressure

White Arc

Flap operating range

Green Arc

Normal operating range

Yellow Arc

Caution range

Red Line (Vne)

Never exceed speed

Rigidity in Space

Gyro tendency to remain fixed in space

Precession

Gyro reaction 90 degrees to applied force

Attitude Indicator

Shows aircraft orientation relative to horizon

Heading Indicator

Directional gyro indicating heading

Turn and Slip Indicator

Shows rate and direction of turn

Lift

Upward force opposing weight

Weight

Force of gravity acting downward

Thrust

Forward force produced by engine

Drag

Rearward force opposing motion

Bernoulli's Principle

Faster airflow creates lower pressure

Newton's Third Law

Every action has an equal and opposite reaction

Parasite Drag

Drag not associated with lift

Form Drag

Drag caused by aircraft shape

Skin Friction Drag

Drag from air contacting aircraft surface

Interference Drag

Drag from intersecting airflow

Induced Drag

Drag caused by producing lift and greatest at slow speeds

Angle of Attack

Angle between chord line and relative wind

Critical Angle of Attack

Point at which lift is lost

Stall

Occurs when airflow separates from the wing

Aggravated Stall

Stall occurring above stall speed

Load Factor

Increases stall speed during turns

Positive Stability

Aircraft returns to original condition after disturbance

Negative Stability

Aircraft diverges further from equilibrium

Neutral Stability

Aircraft maintains new condition

Weather

State of the atmosphere at a given time and place

Troposphere

Lowest atmospheric layer where weather occurs

Coriolis Effect

Earth's rotation causing wind deflection

Cyclonic Flow

Counterclockwise circulation around low pressure

Anticyclonic Flow

Clockwise circulation around high pressure

Cumulonimbus

Thunderstorm cloud

Thunderstorm Stages

Cumulus, mature, dissipating

Warm Front

Warm air replaces cold air producing steady precipitation

Cold Front

Cold air replaces warm air producing heavy showers

Radiation Fog

Forms on clear, calm nights when ground cools

Advection Fog

Forms when warm moist air moves over a colder surface

METAR

Current aviation weather observation

TAF

Terminal aerodrome forecast

Standard Briefing

Most complete weather briefing

Abbreviated Briefing

Shortened or updated briefing

Outlook Briefing

Used when flight is more than six hours away

Deregulation Act of 1978

Removed government control over airline pricing and routes

Hub and Spoke

Airline routing system centered around hubs