Abstract: At approximately 11:30 a.m. on January 11, 2010, Employee #1 was the ranking lead carpenter for a scaffolding erection crew at the NCRA Refinery Vacuum Diesel Cooler Unit. He and his coworkers were assembling scaffolding to access two refinery valves. They erected a scaffold to the first valve. To access the second valve, the crew was erecting a hanging (cantilever) scaffold from the existing scaffold. They were using a scaffold system referred to as "Cuplock" scaffolding. The bars (horizontal pipes) had flat blades welded to each end. The bars were secured to vertical legs by sliding the blades under a locking cup, which was screwed over the top and bottom of each blade. The crew was working from the existing scaffolding to assemble a square frame, cantilever scaffold. The scaffold frame would be 6 ft by 5 ft when finished. They completed two of the four sides of the square frame. The crew began to assemble the third side. Employee #1 stood on a 6-ft bar which was supported on one end. The weld connecting the flat blade to the end of the bar failed. Employee #1 was wearing fall protection equipment but he was not tied off. He fell 27 ft to the concrete floor. Employee #1 was taken to McPherson Memorial Hospital where he was pronounced dead.