Isotropic superfinishing was applied to the third stage spur bull gear and mating pinions along with the second stage bevel gears of a Sikorsky S-76C+ main gearbox. The gearbox completed the standard Acceptance Test Procedure (ATP) and a 200-hour endurance test. During these tests noise@ vibration@ and operating temperatures were shown to be significantly reduced due to lower friction. A description of the tests@ performance data and a general description of the process is presented.