Abstract: On August 2, 2017, one day prior to the accident, Employee #1, a maintenance worker, three other maintenance coworkers, and the supervisor went to the roof of Building 4 to replace the belts on the exhaust system. During this time, the supervisor demonstrated how to replace the belts. The first step was to shut off the power to the motor. The next step was to remove the guard and let the system slow down. Although the system was powered off, the difference in pressure inside the exhaust system prevented the mechanism from coming to a complete stop. The supervisor suggested that they put their hands on the shaft to stop it from rotating. The next day, August 3, 2017 at 9:15 a.m., Employee #1 went to the roof of Building 4 to check on the belts. The employee noticed that the belt on the shaft/motor of exhaust system F4-10 was loose, so he got his tools to tighten the belt. Again, the employee followed the same procedures that he was shown by the supervisor the day before. Employee #1 turned off the power to the motor, and waited for the shaft to slow down. He waited about 10 minutes after the power was shut off, and then proceeded to put his hands on the shaft to stop it from rotating. Although he was wearing gloves, the employees right middle finger got caught in the pinch point between the belt and the pulley of the shaft, and severed approximately one-third of his finger. Employee #1 went to the office and was taken to the hospital. The employee had to have surgery on his finger and was hospitalized for 10 consecutive days.