The subcomponents of an airplane include the airframe, electrical system, flight controls, and brakes.
The airframe is the basic structure of an aircraft and is designed to withstand all aerodynamic forces, as well as the stresses imposed by the weight of the fuel, crew, and payload.
The primary function of an aircraft electrical system is to generate, regulate, and distribute electrical power throughout the aircraft. Several power sources may be used: engine-driven alternating current (AC) generators, auxiliary power units (APUs), and external power. The electrical system operates the flight instruments, essential systems such as anti-icing, and passenger services such as cabin lighting.
The flight controls are the devices and systems that govern the attitude of an aircraft and, as a result, the flightpath it follows. On many conventional airplanes, the primary flight controls use hinged, trailing-edge surfaces called elevators for pitch, ailerons for roll, and the rudder for yaw. These surfaces are operated by the pilot or by an automatic pilot.
Airplane brakes consist of multiple pads (caliper pads) that are hydraulically squeezed toward each other with a rotating disk (rotor) between them. The pads press on the rotor, which turns with the wheels; the increased friction slows the wheels and stops them. Disks and brake pads are made either of steel, like a car’s, or of a carbon material that weighs less and absorbs more energy. Because airplane brakes are used principally during landings and must absorb enormous amounts of energy, their life is measured in landings rather than miles.
