On January 5, 2014, about 1000 central standard time, a Bell B430 helicopter, N430CT, sustained substantial damage during landing when the tail rotor struck a handrail on the crane davit on the West Delta 109 oil platform located in the Gulf of Mexico. The pilot and passenger were not injured. The helicopter was owned and operated by Chevron USA Inc., under the provisions of the 14 Code of Federal Regulations Part 91 as a business flight. Visual meteorological conditions prevailed at the time of the accident. The helicopter departed the Chevron Main Pass 313 oil platform about 0930, and was on a company visual flight rules (VFR) flight plan. The pilot reported that both cranes were shut down on the oil platform and she received a "green" deck for landing. The pilot made a normal approach to the platform. The helicopter was over the landing circle when she turned the helicopter's tail and felt a severe shudder. She immediately landed and shut down the helicopter. The examination of the landing platform and helicopter revealed that the tail rotor blades had struck a handrail on the crane davit, which resulted in substantial damage to the tail rotor gearbox and drivetrain.