What is a critical indication of an engine failure during normal cruise?

During normal cruise, a critical indication of an engine failure is a decrease in RPM. In a multi-engine aircraft, each engine should provide consistent power output, contributing to overall performance and stability. When one engine fails, it typically leads to a noticeable drop in RPM for the affected engine. This decrease is a key indicator that pilots must recognize swiftly, as it directly impacts the aircraft's performance and requires immediate corrective actions, such as initiating appropriate procedures for engine failure.

The functionality of the remaining engine(s) may continue to maintain stable flight and altitude, but it is the decrease in RPM that signifies an immediate issue with one of the engines. Recognizing this sign allows pilots to engage in proper troubleshooting and emergency response, ensuring their safety and the safety of the aircraft.