Abstract: Employees #1 and #2 were maneuvering the basket of a Simon, model K-80, hydraulic mobile aerial platform while ascending to do repair work on the outside of a building at a chemical plant. The basket was attached to the boom by a steel shaft called a boom pivot pin. The boom pivot pin was retained within a boom head assembly by a steel washer and retaining clip. Apparently, during a prior day's use, the boom head assembly was struck by or against something and the retaining clip and washer on one end of the assembly were lost. This caused the pivot pin to gradually work its way out of the head assembly. As the employees maneuvered the basket, it tilted due to the dislodged pivot pin and the employees fell 30 feet to the ground. Both sustained multiple fractures and were hospitalized. Neither employee was wearing a safety belt.