What is the primary reason the T-6B yaws left when PCL is advanced during a climb?

When the PCL (Power Control Lever) is advanced during a climb in the T-6B, the primary reason for the left yaw is due to the dynamics of the propeller blades producing differential thrust. As the aircraft climbs, the downward blade of the propeller experiences a combination of increased angle of attack and higher airflow, resulting in greater lift and thrust production compared to the upward blade. This thrust differential causes a yawing moment to the left.

In this situation, as the downward blade generates more thrust, the right side experiences less thrust from the upward blade. This imbalance in thrust causes the aircraft to turn or yaw to the left. Understanding the interaction between the propeller's blades and the aircraft's motion is crucial in analyzing yaw dynamics during various flight conditions, especially as power settings change.