A gearbox is provided having a housing, a gear having a plurality of teeth operationally configured within the housing, and a laser peening device located within the housing and configured to perform active laser peening on a predetermined surface of the gear while the gear is rotated within the housing. A method of maintaining compressive residual stresses in a gear is provided, the method including operating a gearbox to rotate a gear within the gearbox and laser peening a predetermined surface of the gear with a laser peening device located within the gearbox.