Chapter 1 (Airfraime Construction)

Aircraft structures

Aircraft structures

The components and framework that make up an aircraft.

Aircraft construction techniques

The methods and processes used to build an aircraft.

General aircraft structures

Common items incorporated in aircraft structures.

Pressurization

The process of increasing the air pressure inside an aircraft to allow for flying at high altitudes.

Lifting

The force that allows an aircraft to rise and stay in the air.

Permitted cycles

The number of times an aircraft structure can undergo pressurization cycles before it is limited.

Corrosion

The process of gradual deterioration of a material due to chemical reactions with its environment.

Fretting

The wear and damage caused by repeated rubbing or friction between two surfaces.

Cracking

The formation of small breaks or fractures in a material.

Pitting

The formation of small holes or depressions on a surface.

Engineers Inspection Responsibility

The duty of engineers to inspect the surrounding structure for signs of corrosion, fretting, cracking, pitting, and other defects.

Structural defect

A flaw or weakness in the structure of an aircraft.

Logbook

A record of maintenance and inspections performed on an aircraft.

Approved drawing

A technical drawing that has been authorized for use in the construction or maintenance of an aircraft.

End loads

Loads or forces applied to the ends of structural members.

Side loads

Loads or forces applied to the sides of structural members.

Compression

A stress that pushes or squeezes a material, causing it to become shorter or more compact.

Tension

A stress that pulls or stretches a material, causing it to become longer or more elongated.

Shear

A stress that causes one layer of a material to slide or shift in relation to another layer.

Bending

A stress that causes a material to curve or deform.

Twisting (torsion)

A stress that causes a material to twist or rotate.

Fail-safe

A design concept that ensures the structure can still function even if one component fails.

Damage tolerance

A design concept that allows the structure to withstand serious damage without failure until the damage is detected.

Fatigue indexing

A design concept that takes into account the effects of cyclic loading and fatigue on the structure.

Spar

The main spanwise member of an aircraft's wing or tail.

Stringer

A stiffener that helps sheet materials carry loads along their length.

Bulkhead

A partition within the aircraft's structure that provides structural support and separates different sections.

Station numbers

Numbers used to indicate the positions of components within the aircraft's structure.

Safe life

The estimated period during which a component is considered unlikely to fail.

Crack stopper

A reinforcing member placed to reduce the rate of crack propagation.

Aerodynamic loading

The loads imposed on an aircraft during flight.

Static loading

The loads imposed on an aircraft when it is stationary.

Fuselage

The main structure or body of an aircraft.

Truss type

A type of fuselage construction that uses a rigid framework made up of beams, struts, and bars.

Monocoque type

A type of fuselage construction where the skin carries most of the structural load.

Semi-monocoque type

A type of fuselage construction where the skin and framework share the structural load.

Monocoque Construction

A type of aircraft construction where the skin carries the primary stresses, using formers, frame assemblies, and bulkheads to give shape to the fuselage.

Semi-Monocoque Construction

A modification of monocoque construction where the skin is reinforced by longitudinal members, in addition to formers, frame assemblies, and bulkheads.

Bulkheads

Vertical structural members located at intervals in the fuselage to carry concentrated loads and attach other units.

Frames

Vertical structural members located at intervals in the fuselage to carry concentrated loads and attach other units.

Formers

Vertical structural members located at intervals in the fuselage to give shape to the fuselage.

Longerons

Structural members that take primary bending loads in the fuselage, usually extending across several points of support.

Stringers

Smaller and lighter than longerons, these longitudinal members serve as fill-ins, giving shape and attaching the skin.

Stressed Skin

The metal skin or covering of the fuselage that is riveted to the longerons, bulkheads, and other structural members, carrying part of the load.

Machined Skins

A method of manufacturing aircraft skins where non-riveted areas are machined to reduce weight while retaining strength in the riveted areas.

Chemically Etched Skins

A method of manufacturing aircraft skins where the metal between doubler plates is chemically etched to produce a thin portion of skin, reducing weight.

Milled Structure

A process of manufacturing an integrally constructed skin using a milling process, reducing the number of joints and ensuring smoother airflow over the wing.

Soundproofing

The use of lining panels and blankets made of fiberglass material to insulate the aircraft interior from low ambient temperatures and soundproof it from exterior aircraft noises.

Insulation Blankets

Fiberglass layers encased in a neoprene coated outer fabric that are attached to the cabin structure to insulate and soundproof the interior.

Fasteners

Methods of attaching insulation blankets to the cabin structure, including clip and stud, Velcro fastening strips, and cementing.

Passenger Cabin Lining

The use of insulation blankets behind cabin sidewall panels to insulate and soundproof the interior of the passenger cabin.

Aircraft Doors

Doors on an aircraft that provide access to the interior or exterior of the aircraft.

Non Pressurized Aircraft

Aircraft that do not have pressurized cabins.

Outward Opening Door

A door that opens towards the outside of the aircraft.

Inward Opening Door

A door that opens towards the inside of the aircraft.

Pressurized Aircraft

Aircraft that have pressurized cabins.

Differential Pressure

The difference in pressure between the inside and outside of the aircraft.

Load

The force exerted on a structure or component.

Fuselage

The main body of an aircraft.

Hydraulic

Relating to or operated by a fluid, usually a liquid, under pressure.

Air Conditioning

The process of controlling the temperature, humidity, and air quality in an enclosed space.

Emergency Exit Door

A door specifically designed for passengers to exit the aircraft in case of an emergency.

Hinges

A movable joint or mechanism on which a door swings or rotates.

Cargo Door

A door specifically designed for loading and unloading cargo from an aircraft.

APU Access

Access to the Auxiliary Power Unit, which provides power to the aircraft when the engines are not running.

Landing Gear

The undercarriage of an aircraft that supports it during landing and takeoff.

Elevator Controls

Controls used to move the elevator surfaces on an aircraft, which control pitch.

Access Doors

Doors that provide quick access to equipment and compartments within the aircraft.

Inspection Plates

Plates that can be removed to allow for inspection or maintenance of specific areas or components.

Pressure Doors

Doors that are designed to withstand pressure differentials.

Non Pressure Doors

Doors that are not designed to withstand pressure differentials.

Transparent Panels

Panels made of a material that allows light to pass through, such as windows.

Polishing

The process of making a surface smooth and shiny by rubbing it.

Optical Standards

Standards related to the quality and clarity of light transmission through a material.

Flight Compartment

The area of the aircraft where the pilots and flight crew are located.

Passenger Cabin

The area of the aircraft where the passengers are seated.

Scratch

A mark or damage on a surface caused by scraping or rubbing.

Acrylic Sheet

A type of transparent plastic material commonly used in aircraft windows.

Crazing

A network of fine cracks on the surface of a material.

Stress Crazing

Crazing that occurs on the tension surface of a stressed panel.

Attachment Hole Clearance

The space or gap provided around attachment holes to accommodate thermal expansion or contraction.

Solvent Crazing

Crazing caused by the chemical action of substances on a material.

Cleaning

The process of removing dirt or contaminants from a surface.

Flight Compartment Windows

Windows in the flight compartment of an aircraft that are designed and constructed to withstand internal cabin pressures.

Windscreen

The front window of the flight compartment, usually constructed of layers of glass, vinyl, acrylic plastics, and other materials.

Heater Element

Electrical heating elements sandwiched between the layers of the windscreen for anti-ice protection.

Bolting

Attaching the windscreen to the structure by assembling it into an integral frame that is bolted to the structure.

Retainer

Strips or assemblies used to fix the windscreen into place in the structure.

Laminated Construction

The construction of flight compartment windows using layers of toughened glass on the outside and vinyl layers on the inside.

Passenger Compartment Windows

Windows in the passenger cabin area of an aircraft that are designed differently from flight compartment windows.

Fail-Safe

Design requirements for passenger compartment windows to withstand pressure acting upon them and prevent loss of cabin pressurization.

Window Frame

The structure to which the passenger window frames are attached and act as a load distribution point.

Retaining Bolts

Bolts used to retain both the inner and outer panes of the passenger window in the window frame structure.

Cargo Holds

Compartments in an aircraft for storing cargo, divided into containerized compartments and bulk cargo compartments.

Containerized Compartments

Cargo compartments where luggage or freight is loaded into containers before being loaded into the aircraft.

Bulk Cargo Compartments

Cargo compartments that require various components within the aircraft structure to restrain the movement of smaller items of cargo.

Empennage

The tail section of an aircraft, consisting of a tail cone, fixed surfaces, and movable surfaces.

Tail Cone

The part of the empennage that serves to close and streamline the aft end of the fuselage.

Stabilizers

Fixed surfaces in the empennage that help steady the aircraft, including horizontal and vertical stabilizers.

Moveable Surfaces

Surfaces in the empennage that can be moved to help direct an aircraft's flight, such as rudder and elevators.