What is YDS on Boeing 737? (Yaw Damper Servo)

The Yaw Damper Servo (YDS) is a crucial component of the Boeing 737 aircraft that plays a significant role in maintaining stability during flight. The YDS is responsible for controlling the yaw forces acting on the aircraft and ensuring that it remains on its intended flight path.

The YDS is part of the yaw control system, which consists of the yaw damper, rudder, and associated components. It operates by receiving signals from the yaw damper computer and translating them into mechanical movements that actuate the rudder. These movements help counteract any yawing motion induced by external factors such as wind or turbulence, as well as pilot-induced yawing during manual control.

How Does the Yaw Damper Servo Work?

The YDS functions by using a servo motor that converts electrical signals into physical movements. It receives input from the yaw damper computer, which continuously monitors various aircraft parameters such as yaw rate, roll rate, and airspeed. Based on these inputs, the yaw damper computer determines the appropriate rudder position needed to maintain stable flight.

Once the desired rudder position is determined, the yaw damper computer sends electrical signals to the YDS. The servo motor within the YDS then adjusts the position of the rudder by driving the mechanical linkage connected to it. This process is done in real-time and ensures that the aircraft remains in a stable flight condition, minimizing the effects of yawing motion.

Importance of the Yaw Damper Servo

The Yaw Damper Servo plays a critical role in enhancing flight safety and comfort for both crew and passengers. By counteracting yawing motion, it helps prevent excessive roll and yaw that could potentially lead to loss of control or pilot-induced oscillations. This is particularly crucial during adverse weather conditions or when encountering turbulence.

In addition to its safety benefits, the Yaw Damper Servo also contributes to improving the overall flight experience. By minimizing yawing motion, it helps reduce the sideways swaying sensation that passengers may feel during flight. This contributes to a smoother and more pleasant journey.

In terms of aircraft maintenance, the Yaw Damper Servo undergoes regular inspections and maintenance procedures to ensure its continued reliability and performance. Components within the YDS may be replaced or adjusted based on the manufacturer’s recommendations and maintenance schedules.


The Yaw Damper Servo is an essential component of the Boeing 737 aircraft’s yaw control system. Through the use of a servo motor and real-time input from the yaw damper computer, it helps maintain stability by controlling yaw forces and minimizing yawing motion. Its role in enhancing flight safety and comfort makes it a critical system for ensuring a smooth and stable flight experience.

For more information on the Boeing 737 aircraft and its systems, you can visit the official Boeing website.

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