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5 Important Things to Know About Dual Magneto Ignition

Most lawnmowers, chainsaws, and other small gas-powered engines do not require batteries. Instead, they use a magneto ignition system to generate their own power to start the combustion engine. A similar system is used on aircraft on a much larger scale in the form of dual magneto ignition. In an effort to safeguard assemblies in case of electrical or engine failure, aircraft use a system of two self-contained generators which are each powerful enough to start the engine on their own. This article will cover five important pieces of information to better understand dual magneto ignition.

What Is Dual Magneto Ignition?

A magneto ignition system uses a rotating magnet (magneto) to generate electricity which can then be used to power the spark plugs. Just as in any combustion engine, in an aircraft magneto system, the spark plugs create a spark at the required time to ignite the combustible mixture and start the movement of the engine.

In dual magneto ignition systems, two sets of rotating magnets and coils are used instead of one. Each magneto system is then connected to its own collection of spark plugs so each system can work separately. Aircraft use dual magneto for safety so that if one magneto fails in flight, the other magneto can keep the engine running with only a slight decrease in efficiency.

What Are the Parts of a Magneto Ignition System?

Many parts work in harmony to create a successful dual magneto ignition system. The basic parts are listed below:

Magneto: A magneto consists of one or multiple rotating magnets which interact with a high-output coil to produce a strong electrical current.

Distributor: A distributor invites ignition surges and then distributes them to the spark plugs. Distributors have a rotor, the rotating part which makes and breaks electrical contacts, and a metal electrode.

Primary and Secondary Winding: The primary winding is a coil of about 200 turns of thick wire which can carry a current. The secondary winding is about 20,000 turns of very thin wire wrapped around the primary coil. When the magnets rotate close to these coils, the resulting magnetic field creates a small current which passes through them to the distributor.

Cam: The cam is a piece of armature which rotates the magnets, and it is connected to its respective poles.

Circuit Breaker: Cam motion is designed in such a way that it breaks the circuit when the voltage output is high enough to ignite the spark plugs. When the circuit breaks, the capacitor starts charging.

Capacitor: A capacitor is made up of two metal plates placed at a small distance from each other. Capacitors store electrical charge.

Spark Plug: Spark plugs are used to ignite the combustible air-fuel mixture inside the engine cylinder. They have two metallic electrodes at a small distance from each other.

How does a Magneto Work?

When the magnets rotate past the primary and secondary coils, it generates a magnetic field. This field induces a small amount of current in the coils. As the magnetic field reaches its maximum, a switch in the system opens and triggers the circuit breaker. The circuit breaker stops the flow of current through the primary coil and causes a voltage spike (of about 200 volts). The second coil, which has 100 times more turns than the primary coil, amplifies the voltage to about 20,000 volts, and transfers it to the spark plugs.

What Are the Types of Dual Magneto Ignition Systems?

Magneto ignition systems can be divided into three major types based on their engine rotation:

Magnet Rotating Type: In this type, the magnets rotate near the coils while they stay fixed. In modern days, this is the most common type used.

Polar Inductor Type: In this type, both the coils and magnets are kept fixed. The moving part is a soft iron core which generates voltage by creating its own magnetic field.

Armature Rotating Type: In this type, the magnets are fixed while the armature rotates.

What Are the Benefits of Dual Magneto Ignition?

Magneto systems are very useful and effective devices for ignition in aviation. They generate electricity on their own so there is no need for a battery, and therefore, they weigh less and occupy a smaller space than their alternatives. Magneto systems are also proven to be highly efficient and reliable due to their consistent ability to generate a high voltage spark. Dual magneto systems are beneficial because the single housing of the two magneto systems allows for easier maintenance and ensures that the engine can keep firing even if one magneto fails.


Dual magneto ignition is important to aviation for its proven reliability and capacity to work independently of the surrounding electrical system. With several options to choose from, it is essential to understand the different types. If you are a member of the aviation industry and in the market for dual magneto ignition systems and other aircraft components, then Stacked Purchasing is here to assist you with all your purchasing needs! Owned and operated by ASAP Semiconductor, we are a leading distributor of aircraft components with an extensive inventory of over 2 billion parts. Browse our catalog of available parts on our website or send an Instant Request for Quote (RFQ) form today and get a response from our team of experts within 15 minutes!


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