Aircraft Structures: Primary and Secondary Components

Vocabulary flashcards reviewing primary and secondary aircraft structures, wing and fuselage design, empennage, landing gear, nacelles, and flight control tabs.

Primary Structures

The main load-bearing components of an aircraft essential to flight safety and structural integrity, designed to carry and transfer significant aerodynamic, inertial, and ground loads.

Secondary Structures

Non-critical aircraft components that do not carry primary flight or ground loads, but play key roles in aerodynamics, accessibility, maintenance, and performance.

ATA-100 Zoning System

A standardized system defined by the Air Transport Association of America that divides an aircraft into major sections identified by unique three-digit numbers to streamline maintenance, repair, and inspection.

Cantilever Wing

A wing design with no external bracing where internal spars and ribs carry all flight and ground loads.

Wing Spars

Main longitudinal structural beams in a wing that carry bending loads.

Wing Ribs

Cross-sectional structural frames in a wing that maintain the airfoil shape and distribute loads to the skin.

Stringers

Longitudinal structural stiffeners attached to the skin to prevent buckling under bending and axial loads.

Semi-Monocoque Fuselage

A standard modern aircraft fuselage construction that combines a load-bearing skin with internal frames and stringers.

Pressure Bulkheads

Structural bulkheads located at the forward and aft ends of an aircraft fuselage that seal and maintain the pressurized cabin.

Empennage

The tail assembly of an aircraft that provides pitch and yaw stability and counteracts aerodynamic moments from the wings and fuselage.

Oleo Strut

A shock absorber in the landing gear system that uses air and oil to absorb and dissipate landing impact energy.

Pylon

The primary load-carrying structural frame that securely attaches an engine nacelle to the wing or fuselage.

Fairing

A secondary structure designed to smooth out airflow over irregular surfaces or component junctions to reduce parasitic and form drag.

Vortex Generators

Small, secondary aerodynamic surfaces that create controlled vortices to energize the boundary layer and delay airflow separation.

Wing Fence

An aerodynamic boundary flap on a swept wing designed to stop spanwise, outboard airflow and keep airflow directed chordwise.

Leading-Edge Extensions (LEX)

Forward extensions of the wing root that generate strong, controlled vortices to increase lift and maintain controllability at high angles of attack.

Winglets

Vertical or angled structures at the wingtips designed to control airflow, reduce wingtip vortices, and decrease lift-induced drag.

Trim Tab

A small hinged surface on the trailing edge of a control surface, set independently by the pilot to statically balance the aircraft for hands-off flight.

Servo Tab

A tab directly linked to the flight control input device that deflects in the opposite direction to aerodynamically move control surfaces requiring high manual force.

Anti-Servo Tab

A tab that moves in the same direction as the main control surface to increase control resistance, preventing over-controlling and desensitizing inputs.

Spring Tab

A flight control tab integrated with a spring mechanism that assists the pilot during high-speed flight when control forces are high, while remaining inactive at low speeds.

Frise Aileron

An aileron designed so that when deflected upward, its leading edge pivots down into the airstream to create form drag, mitigating adverse yaw.

Control Horn

A small protruding arm attached near the hinge line of a control surface that provides mechanical leverage for control cables or pushrods.

Artificial 'Q' Feel

A system of springs, dampers, or actuators in fly-by-wire or hydraulically powered aircraft that simulates natural aerodynamic tactile feedback for the pilot.

Braced Wing

A wing structural design that relies on external struts or wires to help support flight and ground loads.

Taildragger Landing Gear

A conventional landing gear arrangement featuring two main wheels forward of the center of gravity and a tailwheel or skid at the rear.

Wing Root Fairing

A secondary aerodynamic surface designed to smooth the junction between the wing and the fuselage, reducing form drag.

Torsional Loads

Twisting structural forces exerted on an aircraft wing or airframe due to aerodynamic moments or control surface deflections.

Cyclic Pressurization Loads

Repeated tensile stresses acting on a fuselage skin caused by cabin pressure changes during climb and descent cycles.

Sharklets

Wingtip devices used on Airbus aircraft to reduce wingtip vortices and lower lift-induced drag.

Elevator

A primary flight control surface hinged to the horizontal stabilizer that controls aircraft movement around the lateral axis (pitch).

Rudder

A primary flight control surface hinged to the vertical stabilizer that controls aircraft movement around the vertical axis (yaw).

Dorsal Strake

An aerodynamic fin located forward of the vertical stabilizer on the upper fuselage that enhances directional stability at high angles of attack.

Wheel Pants

Secondary aerodynamic fairings placed over non-retractable landing gear wheels to reduce parasite drag.