Abstract: Employees #1 through #3 and two coworkers, all scaffold carpenters, were working in the employer's west shipyard in Pascagoula, MS. They were completing alterations to the "dance floor" scaffold aboard the Noble-Max Smith drilling rig, which was being converted to a semi-submersible off-shore rig. The dance floor was a large, fully planked 23,913 sq ft triangular scaffold structure, 235 ft per side, which was suspended 9 ft 1.5 in. below the rig's main drill floor by header bars and scaffold clamps. The typical installation included two clamps: a right-angle clamp attached to a horizontal header bar that was secured to the bottom flanges of drill-floor support beams, and another right-angle clamp that was a back-up attached atop the first clamp. The scaffold frame components being used on this rig were by Aluma Systems USA, Inc., but the clamps used produced by numerous scaffold manufacturers. No horizontal through safety bolts/pins were being used above the clamps. By August 11, 1999, scaffold carpenter crews had lowered and secured the framing for a 7 by 28 ft section of scaffolding, consisting of four 7 by 7 ft bays, located across the aft end of the 25 ft wide by 80 ft long "moon pool." They lowered this section about 3 ft below the dance floor but did not finish planking the four bays. The moon pool was a rectangular opening near the center of the dance floor scaffold through which the rig's drill stem operated. This alteration was needed to afford welders access to the rear of the newly installed lower marine riser platform. At approximately 10:40 p.m. on August 12, 1999, the suspended vertical structural scaffold pole pulled free from the two overhead clamps. This caused the northwest corner of the northern-most 7 by 7 ft bay to drop down; the pole, however, remained attached to the rest of the metal pole frame, which formed the larger 7 by 28 ft scaffold section. The wooden scaffold boards nearest this pole, on which Employees #1 through #3 had been standing, fell 123.5 ft to the dry-dock barge deck. All three employees were wearing full body harnesses with lanyards, but they were not secured to any fixed structure; Employees #1 through #3 were killed., and they were killed. Causal factors appear to be the lack of scaffold-clamp lubrication to ensure maximum clamp tightness when a typical seven-eighths (0.875) in. socket wrench (not a torque wrench) was used.