Abstract: At midnight on March 12, 1997, Employee #1, a foreman at an apple orchard, was adjusting the operating pressure on a tractor-towed spray unit. The unit was on call 24 hours a day, and used as conditions required. Employee #1 had checked it at 6:00 a.m. that day at the Wallace Ranch apple orchard. At approximately 9:30 p.m., he was called at home and told to supervise spraying operations at Sausalito Ranch orchard. He reached the ranch at approximately 11:00 p.m., where he met his brother, the tractor operator. Employee #1 climbed over the power take-off (PTO) drive line and stood on the frame of the spray unit to adjust the pressure valve located on the right side of the tank. His right lower leg was against the right side shield for the PTO drive line and the U-Joint when it became caught in the equipment. He suffered multiple fractures and lacerations, and was transported to Sierra View Hospital for treatment. Employee #1 had been trained to walk around the tractor and spray unit, and never to cross over the drive line. In addition, both he and his brother said they gave the unit only cursory visual checks before starting it, and not a thorough hands-on check. This fact, coupled with the darkness and the fact that the rear light on the unit was not working, contributed to their not noticing that a bolt was missing on the shield.