All About Aircraft Magnetos

What are aircraft magnetos?

A magneto is a self-contained electrical generator that uses permanent magnets to produce a high voltage, alternating current. Magnetos are used to provide pulses of electricity that are high enough to fire engine spark plugs. They don’t need any external electrical source to function, so they are widely used in small engines like chainsaws and lawnmowers that don’t have an electrical supply. However, they are also used in aircraft with piston engines despite usually having an electrical supply because of their reliability.

An aircraft magneto has a permanent magnet on a rotor that spins next to a high-output coil. The spinning magnets generate electricity that reaches up to 20,000 to 30,000 volts. When this value is achieved, a distributor transfers the electricity to the spark plug that ignites the fuel-air mixture inside the engine.

Common types of aircraft magnetos

There are different types of aircraft magnetos, and each type has its unique characteristics. Here are the most common types of magnetos used in aviation.

Slick Magnetos

Slick Magnetos have been manufactured by Champion Aerospace since the 1990s. This type of magneto has a smaller and lighter design compared to other alternatives. Because of these features, the Slick Magneto is easy to install. It also has a noise suppression feature that allowed the removal of magneto filters.

The Slick Magnetos are engineered to have balanced wear and tear on their parts, making their service schedule predictable. One more advantage of using Slick Magnetos is that maintenance is relatively easy because of the new parts used for servicing.

Bendix Dual Magnetos

Magnetos are often used in pairs. In this type of aircraft magneto, the left and right aircraft magnetos are contained in a single casing and are operated by a single magnet and engine drive. Because of this configuration, dual magnetos offer a significant reduction in weight and space used. Aside from that, the single-case design results in more regular maintenance.

Teledyne Continental Motors was the producer of the dual magnetos. The line ended in production back in October 2010. They released two series of the dual magnetos, D2000 and D3000, which differed in the housing design.

Bendix Single Magnetos

The Bendix Single Magnetos, or what they call the “Bendix Mag,” is another magneto manufactured by Teledyne Continental Motors. The Bendix Mag has been in production since 1947. Over the decades, this magneto has proven its reliability. It has a compact and lightweight design that produces high output. The Bendix Mag has multiple variations available for different aircraft applications.

How do aircraft magnetos work?

When you turn the key inside the cockpit, your plane’s engine just suddenly starts running. But that’s because of the magnetos. Here’s exactly how they work.

As the magneto’s magnet spins, it produces a magnetic flux that passes through a high output coil with two separate windings. The primary winding is made of heavy copper, while the secondary winding is made of a finer wire with an exponentially high number of turns. A magnetic field created by the spinning magnet passes through the primary winding. The magnetic field induces a small amount of current in the primary winding. A switch breaks the flow of current in the primary winding when it reaches the maximum, causing a voltage spike. However, this amount is not enough. The secondary winding, which generally has about 100 times more turns than the primary, amplifies the voltage to the desired value ranging from 20,000 to 30,000 volts. This voltage is then fed to the spark plug to ignite the fuel-air mixture.

To visualize it better, you can take a look at an image of a magneto with labeled parts by clicking this link.

Magnetos are often found in pairs: left and right. Each one fires one spark plug per cylinder. This arrangement ensures redundancy. Whenever one fails, the engine will continue to run, albeit less efficient.

Aircraft magnetos are essential parts of the engine that allows it to run. So, you’ll want your plane’s magnetos to work as they should. But just as the magnetos are essential, so is your plane’s exhaust system. Keep your aircraft exhaust in excellent condition by letting us take care of it. Knisley Exhaust is your partner in aviation exhaust systems. We would gladly service your plane! All you need is to call us at 800-522-6990, and we can schedule an appointment!