This chapter presents several examples of asymmetric gear application. Experimental application of spur asymmetric gears was done for a gear drive of the small size gas-turbine engine 9I56 made by The Kaluga Dvigatel plant. With a goal to explore the acoustic characteristics of the asymmetric gears, the serially made helical gears were used as a benchmark for comparison with the experimental spur asymmetric tooth gears. In order to make the prototype gears quickly, their manufacturing process was altered compared to the mass-produced benchmark helical gears. Vibro-testing of the 5I56 engine gearbox with the benchmark helical and asymmetric spur gears was done to evaluate the acoustic characteristics of the asymmetric gears at the testing rig. The assembly of the gearbox includes the selection of planet gears and their initial angular orientation based on transmission error function of every gear. A comparison criterion was a maximum vibration amplitude at the gear tooth mesh frequency.