In a multiengine airplane with clockwise rotating engines, which engine is considered the critical engine?

The critical engine in a multiengine airplane refers to the engine whose failure would most adversely affect the aircraft's performance and controllability. In an aircraft with clockwise rotating engines, the left engine is considered the critical engine because of its position in relation to the centerline of the fuselage and the effects of yaw and roll that occur when it fails.

When the left engine fails, the asymmetrical thrust produced by the right engine (which is farther from the centerline) creates a significant yawing moment to the left. This moment requires corrective input from the pilot, typically involving aileron and rudder adjustments, to maintain control and prevent the aircraft from rolling toward the inoperative engine. The farther distance of the right engine’s thrust line from the centerline exacerbates this effect, making it more challenging to maintain straight flight.

Thus, a left engine failure is critical because it introduces a significant balance and control issue, thereby necessitating a greater response from the pilot to manage the aircraft’s flight path. This knowledge is essential for flight instructors and pilots to ensure safe operations under various conditions, highlighting the importance of critical engine identification during training and flight planning.