What can lead to afterfiring in an aircraft engine?

Afterfiring in an aircraft engine is primarily caused by an excessively rich fuel mixture. When the fuel mixture is too rich, there is an abundance of fuel compared to the amount of air in the combustion process. This leads to incomplete combustion, where some unburned fuel makes its way into the exhaust system.

Once in the exhaust, the unburned fuel can ignite due to the high temperatures present in that environment or through the heat generated by the engine components. This ignition can produce a combustion event in the exhaust system itself, resulting in a distinctive popping or banging sound—known as afterfiring.

Furthermore, the production of afterfire indicates a malfunction in the combustion process, often signaling the need for adjustments in the fuel-air mixture. Maintaining proper mixture ratios is crucial to ensure efficient engine performance and to prevent potential damage from afterfiring.