Abstract: On March 24, 1999, a 24-year-old employee (Employee #1) was installing a punch and die on a drop hammer in the rapid fabrication department of an aircraft parts manufacturing company. The drop hammer was built by Rohr in 1948 (Serial Number 3-1732). Employee #1 was aligning the bolts that join the punch and die to the drop hammer head. The drop hammer head was resting on the bolts and was 90 percent aligned and not blocked. Employee #1 then went to the front of the drop hammer table and began pushing with a metal push stick. As Employee #1 pushed, the bolts aligned and the drop hammer head dropped into place, catching and smashing Employee #1's right thumb between the hammer head and metal push stick. This resulted in an open fracture of the thumb which required hospitalization and surgery.