Abstract: At approximately 5:45 p.m. on February 11, 1999, Employee #1, an aircraft mechanic, and his coworker/supervisor were setting up railing cables on the aft side (inboard end) of a C-17 aircraft wing. Employee #1 was pulling the cable from the spool and walking with it while the coworker guided the cable out of the spool, which was mounted at the end of the wing. While they did this, two other coworkers were at the outboard end, fixing the cable. As Employee #1 was pulling the cable, it became entangled. Employee #1 asked the supervisor to clear the cable and the supervisor complied, whereupon Employee #1 completed pulling the cable on the forward side and then repeated the process on the aft side. As he was walking backward with the cable, his left foot stepped in the 13 in. by 18 in. oval tank access hole at station #116; he fell on his left elbow, which prevented him from falling in further. Coworkers held him until paramedics arrived and rescued him. Employee #1 sustained a fractured left ulna and was transported to Long Beach Memorial Medical Center, where he was hospitalized for 28 hours. The 14 access holes on the wing where the men were working were not guarded. Further, Employee #1 had never done this kind of work before and had not been trained for this kind of operation.