Abstract: Torsional oscillations of helicopter rotor blades are reduced with stall, otherwise leading to such torsional oscillations, precluded consistent with allowable high angle of attack, by sucking air from the boundary layer on the upper surface of the blade near the leading edge thereof at a radial location of 80-90% maximum radius thereof and pumping the sucked boundary layer air, utilizing the inherent centrifugal pumping capability of the blade by establishing an exhaust of the centrifugal pumping passage within the blade which allows adequate pumping for the torsional oscillation reduction purpose consistent with the required rate flow of air.