Abstract: At approximately 3:30 p.m. on September 17, 1992, employees were using pump jack scaffolding to caulk siding on the west end of building F. Five jacks and uprights were in use, connected by four 4 by 12 planks for a platform. The platform was approximately 20 ft above ground. One employee was working in the center of the scaffold. There was no access ladder for the scaffold. Another employee wanted to get up on the scaffold and climbed up the 4 in. by 4 in. upright at the south end. When he reached the platform, the plank was not secured to the pump jack bracket and turned as he attempted to climb up on it. When the plank turned, the next plank turned over. Employee #1, who was standing on the second plank, fell to the ground when the plank turned. He landed on his feet, but fell forward and his face and head hit the ground, knocking him unconscious. Employee #1 was in a coma for several days, but had regained consciousness by September 23, 1992.