What is specified by the term “critical engine” in a twin-engine aircraft?

The term “critical engine” in a twin-engine aircraft refers specifically to the engine whose failure results in the most adverse aerodynamic effects, particularly loss of control and increased yawing moment towards the inoperative engine. In many light twin aircraft, the critical engine is typically the engine that is located on the side that is further from the aircraft's centerline. This means that if this engine fails, the aircraft experiences a greater tendency to yaw towards that side, making it more difficult to control during the critical phases of flight, such as takeoff and climb.

Understanding which engine is critical helps pilots prepare for engine-out scenarios, as they must recognize the increased drag and adverse yaw that follows an engine failure. This knowledge is essential for managing the aircraft's performance and ensuring a safe response to an engine failure.

The other options are less relevant to the definition of a critical engine. While horsepower, distance from the center of gravity, or climb performance are important considerations in aircraft operation, they do not directly relate to the term "critical engine" in the context of effective flight control following an engine failure.