When considering high-speed gear transmission, the power loss due to the fluid drag torque generated by the gear rotation in air/oil mist may dominate the other losses. This windage power loss (WPL) must be therefore studied in order to mitigate its impact. Numerous investigations have been made in the past essentially to propose WPL model. However the influence of helix angle is not clearly understood since most of the previous studies considered spur gears. Experiments have still shown that WPL value is modified when helix angle value becomes not null. More investigations are therefore needed to reach appropriate model. The purpose of this paper is to build a numerical model using CFD method which is capable to estimate WPL generated by helical gears whose characteristics differ from their helix angle values. The helix angle influence is highlighted since both the volumetric flow rate which is expelled by the rotating gear and WPL are affected by a modification of this parameter.