What is one potential cause of afterfiring in an aircraft engine?

Afterfiring in an aircraft engine typically occurs when unburned fuel ignites in the exhaust system. One potential cause for this is an excessively rich mixture, where there is more fuel relative to the amount of air entering the combustion chamber. When the mixture is too rich, it means that not all of the fuel may burn during the combustion process. This unburned fuel can then enter the exhaust system.

As the hot exhaust gases reach the hot components of the exhaust system or the muffler, the unburned fuel can ignite, causing a loud pop or bang—the phenomenon known as afterfiring. An excessively rich mixture is often a result of incorrect fuel-air ratios due to issues such as a malfunctioning carburetor or fuel injection system.

Understanding this helps to troubleshoot and maintain the engine properly, making adjustments to the fuel system whenever excessive richness is suspected.