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A Comprehensive Look at Aircraft Engine Fire Detection & Extinguishing Systems

Safety is of paramount importance in aviation operations, and one critical aspect of flight safety is having protection against the dangers of engine fires. While any fire during flight is a significant hazard, engine fires in particular are truly concerning, as such assemblies are necessary to create lift and contain flammable materials like fuel.

As such, modern planes employ aircraft engine fire detection and extinguishing systems to both detect and suppress engine fires when they arise. In this blog, we will delve into the intricacies of these systems by exploring their components, functionality, and significance so that you can better understand how they promote safe travel.

The Fire Detection System

To effectively fight an engine fire, it must first be detected. In large aircraft, engine and auxiliary power unit (APU) assemblies will be lined with loops of firewires where the chance of ignition is most severe. These components are tubular structures featuring an electrode encapsulated within an insulating material and steel tube. This firewire is attached to a control unit or fire detection computer, and a constant voltage runs through the tube for as long as the temperature remains unchanged.

If a fire were to occur, the resistance of the insulating materials would decrease, causing a rise in current between the electrode and outer steel tube. In response, the fire detection computer issues a warning to the cockpit. However, to guarantee redundancy in the case of a failure or issue, aircraft are designed with multiple firewire loops. In many cases, two loops may also be present so that a fire warning only goes off when both face a rise in current.

In other aircraft, fire detection may be carried out using a gas-type system. With this design, a tube is sealed on one side and filled with helium gas under pressure. Within the tube is a core material that is designed to create hydrogen gas when faced with heat, and the unsealed side of the tube is connected to a fire detection and responder unit.

Furthermore, inside the responder unit, an integrity and alarm switch are present. The integrity switch is held closed when helium pressure is stagnant, while the alarm switch always remains open. As heat increases in response to a fire and hydrogen gas is released, gas pressure will eventually actuate the alarm switch to generate a warning.

The Fire Extinguishing System

While the aforementioned systems are intended for detection, there must also be systems in place to fight the actual fire. Oftentimes, onboard fire extinguishing systems will come in the form of fire bottles that contain pressurized extinguishants. The most popular extinguishant is Halon 1301, selected due to its non-corrosive and non-conductive properties.

Additionally, while the industry standard is having two fire bottles per engine, smaller aircraft may only have one bottle for each. These fire bottles are also fairly straightforward to use, and discharge disks are present to indicate pressurization.


While these systems are crucial for detecting and fighting engine fires during flight operations, pilots and personnel must also be trained on how to effectively respond to such situations so that emergency landings, diversions, or other safety choices can be effectively made. Aircraft and their safety systems should also undergo regular inspection and maintenance to guarantee that all components are airworthy and dependable.

If any safety system is showing signs of malfunction, significant wear, or otherwise is unable to perform reliably, it should be repaired or replaced as soon as possible. Luckily for you, we at Aerospace Domain can help you secure everything you require for your operations with highly competitive pricing and rapid lead times for your benefit.   

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