Does an aircraft with counter-rotating propellers have a critical engine?

An aircraft equipped with counter-rotating propellers does not have a critical engine. In a multi-engine aircraft, the critical engine is typically defined as the one whose failure would result in the most adverse yaw, requiring significant corrective input from the pilot to maintain control.

Counter-rotating propellers help to cancel out the adverse yaw effects that normally occur during engine failure in conventional prop configurations where both engines rotate in the same direction. This is because the opposing rotation of the propellers counters the torque and P-factor effects that create a tendency for the aircraft to yaw away from the dead engine.

In practical terms, since both propellers are spinning in opposite directions, the aerodynamic forces they produce tend to balance each other out, eliminating the critical engine scenario typical of traditional configurations. Thus, regardless of flight conditions or phases such as takeoff, the concept of a critical engine does not apply in the context of aircraft with counter-rotating propellers.