Abstract: At approximately 11:20 a.m. on February 24, 1995, employees of Dillingham Construction, NA, Inc., Hanford, CA, including Employee #1, were each replacing 51 tubes, 40 ft long by 3 in. diameter and weighing 150 lb, through the top of a heat tower, which contained 670 tubes. Tubes were being installed vertically by means of a truck-mounted hydro crane with jib. The tubes were supported by a bullet guide in vertical mode; the guide was connected by a shackle to a vertical 1/4 in. galvanized aircraft cable sling connected, in turn, to a 4 ft long nylon sling by means of a second shackle. The top end of the nylon sling, the eye, was connected to a hook on the whip line (single part line mode). The crane operator and Employee #1, a signalman/pusher, were communicating by means of hand-held radios. Transmissions were becoming subjected to harmonic frequency interference. During the insertion of tube #39 through sheet #3, the guide became stuck. While being cleared, the guide became hung up on sheet #3. When the crane operator attempted to hold the load, as commanded, the cable's sling separated upward and injured Employee #1's left hand. Suffering a fracture and a puncture wound, Employee #1 was removed to Hanford Community Hospital, where he was admitted and treated.