How does engine torque affect the critical engine in a multi-engine aircraft?

In a multi-engine aircraft, the concept of torque is essential in understanding how asymmetrical thrust affects the aircraft's handling characteristics. The torque produced by the engines can lead to differential thrust, which is particularly crucial in defining the critical engine.

The critical engine is the engine whose failure would most adversely affect the performance and controllability of the aircraft. In conventional multi-engine configurations, especially with a centerline thrust design, the left engine is typically considered the critical engine due to the torque effect that creates a tendency to roll towards the inoperative engine.

When the left engine is operating, it produces torque that induces a rolling moment in the opposite direction, helping to counteract any yawing motion caused by differential thrust. This left engine's torque stabilizes the aircraft and assists the pilot in maintaining control during normal operations.

If the left engine fails, the right engine's torque creates a greater asymmetrical thrust, leading to a significant rolling tendency towards the inoperative engine. Therefore, understanding that the left engine's torque counters asymmetrical thrust is crucial for managing aircraft control in the event of an engine failure. This knowledge helps pilots anticipate and respond effectively to maintain control of the aircraft.