Main Rotor Damper Assembly for Leonardo AW189 helicopter. The damper is installed between the main rotor hub and the fuselage to reduce and control vibratory loads and oscillations transmitted from the rotor to the airframe. It helps improve ride comfort, reduce fatigue on structural components, and enhance handling stability. The assembly consists of a hydraulic cylinder with internal orificing and a floating piston, connected at both ends via spherical bearings. Part Number: 8G6220V00151. Replaces P/N 4F6220V00251. ATA Chapter 62 – Main Rotor.