The 30mm wheel type anti-aircraft gun replaces the aging anti-aircraft gun in the front and is a weapon system for local anti-aircraft defense against enemy aircraft and small unmanned vehicles. In the field, damage to the turret hatch/closed hatch pin occurred between the operation of the wheel type anti-aircraft gun. As a result of the sem analysis of the hatch pin fracture surface, it appears that brittleness fracture occurred and fatigue fracture occurred at the final fracture surface while reaching the fatigue strength by repetitive loads. The hatch angle fixing pin and bracket shapes were changed to disperse the stress concentration. As a result of checking the location of the vulnerable area of the hatch pin and the shear stress value through structural analysis, the safety factor improved from 1.46 to 2.95 after improvement. Through this study, it is expected to be used as a reference material for failure analysis and design plan for the existing system in the future.