Gear Fault Detection is a significant issue with many rotating machines that are connected to a gearbox. Damage that is not detected in a timely manner can result in serious machinery damage, catastrophic injuries, and significant financial losses. The purpose of this paper is focused to study the stress generated on the contact surfaces of gear pair. The case study of a gear (with 75 teeth) and pinion (with 25 teeth) from Alloy steel are analyzed using theoretical Von-Mises's equation using finite element method under static conditions using software package SOLIDWORKS. The contact stress between the gear tooth pair's engagement impacts the gear's ability to transmit power. So, the thesis studies the stresses on different faults on the same boundary condition.