On December 29, 1993, at about 1655 central standard time, a Kaman HH-43B/F, N5197W, collided with the ground during an emergency descent near Mount Vernon, Alabama. The helicopter was operated by Scott Paper Company under 14 CFR Part 133, and visual flight rules. Visual meteorological conditions prevailed. A flight plan was not filed for the external lift, long-line, logging flight. The commercial pilot was not injured, and the helicopter was substantially damaged. The local flight had departed a logging work area at an unspecified time. The pilot reported a partial loss of rotor system control, after lifting an external load of logs. The external load was jettisoned. Control of the helicopter could be maintained while in straight and level flight, with the collective at its lowest pitch setting. As the pilot attempted to slow the helicopter's descent rate for a landing, control was lost. The collective was lowered, and the helicopter collided with the ground. The rotor system contacted the ground and shattered, and the fuselage landed hard. The operator examined the wreckage and discovered that the cotter pin for the right rotor head teeter pin retention nut was absent. Both rotor hub assemblies had been replaced because of normal maintenance action on December 13, 1993. The operator stated that a maintenance action checklist would be developed to supplement the Maintenance Manual to preclude a similar oversight in the future.