This paper proposes an active damping system to mitigate the vibration of bladed assemblies. The damping system consists of multiple pairs of piezoelectric patches accompanied by a decentralized control configuration. To maximize the control authority, the size and the location of the patches are optimized based on maximizing the strain energy. In each pair, one patch is used as a sensor and the other one as an actuator. As the control plants of such configuration have no high-frequency roll-off, a second-order low-pass filter known as a positive position feedback (PPF) controller is considered as the control law. The parameters of the controller are tuned based on maximizing the closed-loop damping of the first family of modes. This active damping system is implemented on a monobloc bladed rail which is representative of a portion of bladed drum, i.e., BluM. Numerical simulations are performed to assess the performance of the designed control system and experimental tests are carried out to validate the numerical design.