What happens during a right descending turn if excessive left rudder is applied?

When excessive left rudder is applied during a right descending turn, the airplane will enter a slip. A slip occurs when the aircraft is not coordinated in its turn; in this case, the left rudder command causes the airplane to move sideways toward the outside of the turn while still maintaining the right bank angle.

In a right turn, the aircraft naturally wants to yaw to the left due to the bank angle and the lift vector’s change. Applying too much left rudder counteracts this yaw, leading to a situation where the aircraft is not in a balanced state. The airplane may then start to drift sideways relative to the turn, resulting in a slip which is characterized by a loss of efficiency in the turn and requires corrections to regain proper coordination.

Proper coordination is essential in turns to ensure the aircraft performs as expected, helping maintain altitude and control while preventing adverse aerodynamic effects.