What are the effects on an engine of a low power, high speed descent?

Focusing on the concept of a low power, high-speed descent, it is important to understand how such operational conditions affect engine performance. When an aircraft descends at high speeds while maintaining low power settings, the airflow over the engine and its components increases significantly. This can lead to several thermal and operational effects.

One primary concern is engine overcooling. During a high-speed descent, the increased airflow can cool engine components more than intended. This can lead to situations where the engine temperature drops below optimal operating levels. If the engine runs excessively cool, it can cause issues such as ineffective combustion and increased fuel consumption due to improper fuel-air mixture.

Furthermore, carburettor icing can occur under these conditions, particularly if the moisture in the air combines with the low temperature created by overcooling. Carburettor icing is a result of the reduction in temperature as fuel vaporizes, which can happen more readily in descending conditions without sufficient power to maintain engine heat.

Overall, low power during a high-speed descent can create a perfect storm for engine overcooling and carburettor icing, leading to operational inefficiencies and possible operational hazards.