How Do Spark Plugs Within Aircraft Engines Work?

For a majority of aircraft to generate thrust and achieve flight, they rely on robust internal combustion engines that ignite fuel and air mixtures. In order for the combustion process to be efficiently and safely carried out, the aircraft ignition system relies on a specific component known as a spark plug. While small in size, the spark plugs in aircraft are paramount to their operation as ignition would not be possible without them. In this blog, we will discuss spark plugs and their most common types, allowing you to better understand how they are used in standard flight operations.

Also known as sparking plugs, spark plugs in aircraft are used to transmit electric current from the aircraft ignition system to the combustion chamber in order to ignite fuel and air mixtures. In their most basic form, spark plugs are cylinders composed of metal and ceramic, and threading on their body allows them to be fastened onto engine cylinders. Unlike the more conventional types of spark plugs that may be found in various automobiles, many spark plugs in aircraft feature two electrodes or prongs that are placed on the sides of a central post. With a gap located between the electrodes, a spark can be generated to ignite fuel and air mixtures. With this basic functionality, spark plugs serve as a metering device for electrical energy.

As spark plugs are crucial for the basic functionality of aircraft engines and the aircraft ignition system, nearly every modern certified aircraft will implement two spark plugs for each cylinder to ensure redundancy. With an extra spark plug, firing can continue even in the event of a spark plug failure. To check spark plugs, pilots will typically conduct a magneto ignition check before conducting a flight operation.

Across aircraft, there are two types of aircraft spark plugs that are the most common. Fine wire plugs are one of the two major types, and they feature a single, small-gauge iridium wire. By using iridium for the construction of the wire, the spark plug exhibits a much slower rate of erosion and may burn fuel more efficiently. Despite this, fine wire types are considered less cost-efficient for their characteristics as compared to the other type.

Massive spark plugs are the other common spark plug type for aircraft, and they serve as the dominant component for their implementation. While less durable as compared to the fine wire spark plug, massive spark plugs are quite cost-efficient. Additionally, the massive spark plug utilizes the two-electrode configuration for ignition that is most common for aircraft engines, unlike fine-wire types that are more similar to spark plugs found within automobile assemblies.

With all spark plug types, consistent operations will wear down on components, causing them to lose integrity over time until they begin exhibiting poor performance or fail. To ensure that aircraft spark plugs always function as intended, they should be regularly tested, inspected, and maintained as necessary. To best maintain a spark plug, components should be cleaned in accordance to manufacturer specifications. Once spark plugs reach an unacceptable limit for airworthiness, they should be replaced before conducting another flight operation. 

With top quality spark plugs that are well maintained, such components can steadily be relied upon for the combustion of fuel and air mixtures within aircraft engines. NSN Components is an online distributor of aircraft parts, and we are your sourcing solution for items pertaining to the aircraft ignition system, aircraft engines, and much more. As you browse our expansive part and manufacturer catalogs, we invite you to submit an Instant RFQ form at any time for the items that you are interested in. Upon receiving your request, our team of industry experts will quickly craft you a quote that serves as a unique solution to your individual needs.

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1. alex marsh
2. Posted on March 11, 2021
3. aviation

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