Ask Captain Dan Baz : Our Resident Pilot Answers Flight Questions. Electricity on Airplanes – April 15, 2012

CFN – Pilot Dan Baz is answering your flying questions here on the Cornwall Free News. If you have a question about flying you can email Captain Dan or post below.



Airplanes at the beginning of aviation had no electrical systems at all. However, it was not long before airplanes needed lights to fly at night. In the 1920’s and 1930’s, as the electronic industry was developing, airplanes were equipped with Radio Transceivers and Receivers for voice communications, electronic systems for navigation and electric flight instruments.  Early small airplanes used small air driven generators. These were mounted externally on the airplane, driven by a small propeller. As airplanes grew in size and needed more electrical power, generators were mounted on the engines, in a similar fashion to automotive generators or alternators.

Today, in the 21st century and the age of electronics, we can hardly get by without electricity.  We need to plug in and charge our laptops, iPhones and Blackberrys and many other electronic devices that we can hardly live without. Meals on airplanes are heated in electric ovens. Airplane technology has changed dramatically in the last couple of decades. Electrical systems have become more reliable and dependable.  Airplanes have dozens of computers to run and monitor, flight control and other airplane systems. Flight instrument displays are basically sophisticated computer monitors, navigation and communication systems, they all require electrical power to operate.

Modern airliners today, must have electrical power to fly.  Therefore, airliners now have multiple, redundant electrical sources. There is at least one generator installed on each engine. Airplanes also have an Auxiliary Power Unit (APU) with electric generator, which can supply electrical power in flight as well as for ground use. Some airplanes have additional electric generators powered by airplane’s hydraulic systems. There are airplanes that also have wind driven emergency  generator.  This generator has much bigger capacity than those used in the early years of aviation.  As a last source of electrical power, airplanes have batteries and inverters, which can provide electric power to flight controls, flight displays and essential equipment, long enough for the crew to land the airplane.

Failure of any one generator does not compromise operation of modern airplanes. Electrical power produced by the generators is  three phase, 115 volts AC, at 400 Hz. High frequency allows for smaller and lighter electric motors in various airplane systems. On the ground, electric power for an airplane is supplied by a generator driven by airplane’s auxiliary power unit (APU), or from an external electric power source, through an umbilical cable connected to the airplane.

A bit more about Captain Dan:

Captain Dan Baz enrolled in Flight School at the age of 16.
He has completed studies in Aircraft Engineering and Master of Business Administration. He has been at the controls of many different types of aircraft, from single engine Cessnas to large intercontinental jets on global routes.
Over the last four decades he has flown thousands of hours up in the blue sky.

Have a question for the Captain ? Send it to Captain Dan Baz Every week a question from the readers will be selected and answer posted in this column.

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