In this study, the aerodynamic performance of the Bonanza light aircraft propeller was investigated by implementing a suction slot on the blade airfoil surface. Previous research has predominantly investigated the use of surface suction slots for delaying flow separation and increasing stall speed on aircraft wings, compressor blades, wind turbines, and UAV propellers. Such slots are generally categorized into two types: active and passive. In the present work, a passive configuration was adopted to prevent additional structural weight and avoid any alteration in the aircraft’s center of gravity during flight. The position of the suction slot on the lower surface of a two-dimensional asymmetric airfoil was determined relative to the leading edge, taking into account the geometric pitch angle at cruise altitude and velocity, as well as the temperature, pressure, and humidity conditions representative of Tehran Mehrabad International Airport. Baseline calculations for a propeller without a slot were carried out using Blade Element Momentum (BEM) theory, complemented by numerical simulations in ANSYS Fluent 2025 R1. The findings indicated that the closer the slot is positioned to the leading edge, the smaller its effect on reducing the lift coefficient. Nevertheless, when the slot was applied according to the geometric dimensions proposed in this study, the lift coefficient (CL) of the propeller blade increased by about 7%, the moment coefficient (Cm) at the reference station increased by about 6%, and the overall propeller efficiency (η) improved by approximately 4% within the advance ratio range.