The meshing action of Driven gear resulted in the wear of teeth as shown in Fig. 11. The shearing of hard case from the core and plastic flow at the teeth surface was promoted by the existence of larger hardness gradient at core/case interface. The intergranular surface cracks and fins at the edges corresponded to the detachment of hardened case from the core completely. The sever wear and deformation caused improper meshing of gears teeth which ultimately resulted in non homogeneous distribution of local stresses and failed ultimately. For instance the damaged gears system did not transmit power from generator to the engine assembly hence reduced RPM in the engine.