What are common indicators of engine failure during flight?

Engine failure during flight can often be identified by a decrease in engine RPM, abnormal engine temperature, and changes in engine sounds. These indicators are critical because they indicate that the engine is not functioning optimally.

When an engine experiences failure, it may not produce the necessary thrust, leading to a noticeable drop in RPM, which is the measure of how fast the engine is running. Additionally, abnormal engine temperatures—either too cool or excessively hot—can signal issues such as fuel flow problems or mechanical malfunctions. Changes in engine sounds can also provide vital clues; for instance, a sudden roughness or loss of power can be alarming and indicate that something is amiss with the engine.

The other options don't provide relevant indicators of engine failure. For example, an increase in airspeed and altitude may suggest that the aircraft is climbing efficiently, which is typically not associated with engine issues. A lack of control inputs might point to pilot inaction rather than an engine-related problem. Finally, stabilized flight patterns and normal performance would suggest that the engine is functioning correctly, thereby not aligning with the indicators of failure.