How Are Wire Harnesses Used In The Aviation Industry?

When you get on a commercial airliner, do you ever think about all of the different electrical components that have to go into the construction of the plane? Sure, there is all of the wiring that allows you to watch your in-flight movies, but as you might imagine, this composes just a very small portion of an airplaneā€™s total wiring. In fact, nearly every aircraft must have electrical power for navigation, taxiing about the runway, operating landing gears and lighting, as well as radio operations.

All of these components are connected by miles and miles of wires, wire harnesses, and connectors. If you have never heard of a wire harness, it is essentially a series of wires that are bundled together for maximum space efficiency, protection from vibration, and to achieve some electrical purpose. Even for the hobbyist pilot, it pays to have some knowledge of these electrical systems.

Basic Electrical System

Most avionic electrical systems are composed of switches and fuses, as well as wiring and connectors. Voltage flows through devices via these wiring harnesses and should be monitored by the pilot. The rest of the electrical system consists of a master switch, bus bars, ammeter and voltmeter, and circuit breakers to control the various devices.

The Master Switch

This switch turns the whole system on or off using a heavy-duty relay. When in the ON position, electrical power is supplied to the bus bars of each device on the plane. Each bus bar will also have its own circuit breaker. This is to prevent a short circuit from taking out other important components such as radio and navigation systems.

Bus Bar

A bus bar is a thick copper wire that is connected to circuit breakers and serve a similar function. In a plane with more than one alternator, bus bars can be interconnected in an array, should an alternator fail. This ensures that you are always receiving electrical power to your most essential devices.

Monitoring Amps and Volt

An ammeter or voltmeter is usually installed in the instrument panel so the pilot can monitor the current (measured by the flow of electrons) from the alternator. Typically two different types of ammeters will be used, one that measures current to or from the battery, and one that indicates when an alternator is delivering an electrical load.

Wiring and Grounding

As a basic tenet of electricity, every device needs two wires to connect to direct current or DC power. One will be connected to the positive, and one to the negative, and typically the frame of the aircraft will be used as a ground, however this is not considered the best method. Instead, it is better to have a common grounding point to which all return wires can be grounded to. This avoids current pulses which can flow through the aircrafts frame and cause unexpected interference with some devices.

All in all, it takes over a full year to wire a commercial aircraft. To find out more about the types of wires and wire harnesses used in commercial aircraft, head over to LoDan now!