Abstract: On July 3, 1993, Employee #1 and another maintenance mechanic entered the attic of Building #1 to track down an air pressure problem with AMSCO #1. Employee #1 stepped on a 29 inch by 43 inch plywood board that had been nailed from the ceiling up through the rafters to cover an old ladder chute opening. The nails gave way and Employee #1 fell through the ceiling opening to the floor, sustaining a broken pelvis. The location of the fall was in the hallway in front of Room #118. The employer immediately abated this condition by nailing plywood boards on the topside of the rafters to make the floor more secure for future access and egress.