A study has been carried out to optimize the size of the bypass duct, improve engine performance and prevent engine damage caused by icing particles in a commuter category aircraft turboprop engine air intake. Computational fluid dynamics (CFD) analysis using Ansys software is employed to visualize flow parameters and study the impact of design modifications. The study emphasizes the importance of bypass ratio optimization in achieving efficient and resilient engine operation to maintain ram recovery at engine inlet screen. CFD analysis under various aircraft conditions at different altitude provides insights into flow behavior and aids in optimizing the bypass duct size. The results indicate a decrease in the bypass ratio from 28 to 18% at minimum climb and 38 to 27% at maximum cruise conditions leading to improved engine performance and minimizing the ingress of icing particles into critical engine components with higher ram pressure recovery.