A two-stage linear actuator particularly applicable to aircraft control surfaces. The first stage comprises a rotary input shaft driven by an electric motor having a helical threaded zone in its external surface at its inner end and a plurality of first helical roller gears configured to engage with the rotary input shaft in its helical threaded zone for rotating together. The second stage comprises a plurality of second helical roller gears configured to engage with the first helical roller gears for rotating together and with an output shaft having a helical threaded zone in its external surface at its inner end for converting the rotation of the second helical roller gears in a linear movement of the output shaft.