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Aircraft Electrical System

Gee, that’s shocking!

Let’s look a electricity in a new way.  In this TOPIC, we’ll talk about electricity as if it was water flowing through pipes instead of electrons flowing through wires.  Watch the video above, and then check out these quick cheat-sheet facts for you here:

  • Airplanes are either 14 volt or 28 volt systems (with a 12 volt battery charged up to 14v, or a 24 volt battery charged up to 28v)
  • Alternators (or generators, really the same thing for our purposes) act as a “pump” to pump electricity back into the battery as it is used by the electrical components on the airplane (lights, radios, etc.)
  • Amperage is like “flow” of water, the higher the amperage the more electricity is flowing through the wires
  • Voltage is like “pressure” or PSI of water, the higher the Voltage the higher the “PSI”.  We all know what happens when you have excess pressure in your pipes, they burst; and so do wires and electronics.  Too much voltage and lights and radios start to fail as the small connections inside them “burst”
  • The flow of amperage generates heat.  More flow, more friction, more heat.  Having too much amperage through a wire can build up so much heat it can cause an electrical fire.  Bad news is wires in airplanes tend to be bundled together, and when one gets too hot and burns up, it likes to take out a lot of other wires with it. (when it rains it pours)

Electrical Failure Considerations

It is important to note that not all aircraft are equipped with alternator failure or low voltage lights. Depending upon the age of your aircraft, your first warning sign may unusually poor reception both in regard to transmission distance and reception. (Transmitting induces quite a bit of electrical draw). Become familiar with your aircraft and know what to keep an eye out for.

There are other ways of communicating with air traffic control should you experience an electrical failure. This could be something as simple as using your cell phone to call the control tower for landing clearance or involve the use of light gun signals, which we will discuss in more depth in a later chapter. If landing at an uncontrolled airfield, use extreme caution as other aircraft may not know your position.

Electrical failures can be especially hazardous at night, as aircraft lighting will not work, which will make instrument interpretation and landing difficult, and make it harder if not impossible for other aircraft to see you. Ask your instructor about techniques you can practice for night electrical failures,  and always be sure to keep a headlamp nearby! (Ideally with a “red mode” that will minimally impact your night vision).