Abstract: At approximately 2:45 p.m. on June 12, 2004, Employee #1 was working as an operations manager with Korda & Geis Engineering in Goleta, CA. As his shift was ending, Employee #1 was informed that the arm of CNC milling machine number PDC2 was stuck. Operating properly, this pneumatically powered arm interchanges the various milling tools in the machine. Stuck, it was unable to select a tool. With the machine still energized, Employee #1 grasped the arm with his thumbs on the tool side. The "tool side" is the direction in which the arm would move, when activated, to select a tool. As Employee #1 attempted to move the arm away from the tool, the machine suddenly activated. The arm moved toward the tool, catching Employee #1's left thumb between the arm and one of the machine's maintenance covers. Employee #1's left thumb was amputated just above the nail. He was not hospitalized. Employee #1 was the only supervisory-level employee on site at the time of the incident. He had been employed at Korda & Geis Engineering for eight years and had held the position of manager for eight months. Causal factors for the accident include a lack of effective energy control procedures and a failure to provide appropriate extension tools for the safe adjustment of the milling machine's tool-changing arm.