Abstract: Employees #1 and #2 were installing a duct on the third floor of a building. At the same time, a crane equipped with a wire rope sling was raising a 30-ft-long by 7-ft-5-in.-high by 5-in.-thick modular concrete panel weighing 19,250 lb from ground level to the ninth floor. Richmond 1.25 -in. threaded coil inserts were precast in the panel 6 ft from each end, and it was fitted with Richmond 1.25-in. by 14-in. bolts, swivels, and blocks. The panel's weight was transferred from the crane and sling to two vertical come-alongs for final positioning before it was attached to the building. During this transfer, the change in the angle of suspension caused the 14-in. bolts to come out. The panel fell, breaking through the roof at the fourth-floor level, passing through the third floor, and coming to rest on the second floor. Employees #1 and #2 were struck by the panel. Both of Employee #1's legs were amputated below the knee and he suffered possible spinal injuries. Employee #2 sustained lacerations to his body and a fractured right leg. Both were hospitalized. The 14-in. bolts were not long enough for the concrete panel: 25 in. or 27 in. bolts with proper blocks should have been used.