**5. Conclusion**

Choosing the correct assembly for aircraft power transmission is a key factor in the quest for weight reduction. Although technological advances in mechanical components can help achieve weight reduction in gear systems, their influence is much less than that of choosing the correct gear assembly.

Planetary gear or split torque systems are typically used in helicopter gear transmissions. The fundamental advantage of the split torque systems is that less weight is achieved by equal torque transmission and gear transmission ratios. This advantage is based primarily on arguments as follows:


These arguments would indicate the advisability of using this type of transmission in aircraft gear systems.
