Abstract: On December 27, 2007, Employee #1 and two coworkers were lowering a 15,000 lb chiller that was supported by 6 by 6 wooden blocks onto a concrete pad. Their intended process was to (1) lower one corner approximately 1-1/2 in. before moving to the next corner; (2) repeat the process for all four of the corners; (3) return to the first corner and lower it an additional 1-1/2 in.; (4) continue with each corner in succession until all four corners were resting on the concrete pad. To accomplish the task, they used a 10-ton hydraulic jack to raise one corner high enough to manually replace the 6 by 6 block with a 4 by 4 block, whihc was actually closer to 1-1/2 in. smaller. When all four blocks were replaced, smaller blocks were to be used as replacements in successive cycles around the four corners until the chiller was resting on the pad. On the second corner of the first cycle of block replacements, Employee #1 was operating the hydraulic jack alone, while the two coworkers were nearby cleaning up around the chiller. Employee #1 raised the chiller sufficiently to allow removal of the wooden block when he noticed there was small debris on the concrete in the area where the chiller would eventually rest. He decided to scrape it away, but instead of leaving the wooden block in place, he used it to remove the debris. He was holding the block by its sides and top with his right hand while he swept away the debris. His fingers were on top of the block when the jack suddenly collapsed and the chiller dropped on his right index and middle fingers, crushing them. The two coworkers came to his rescue and jacked up the chiller to allow Employee #1 to remove his hand. Neither of the coworkers witnessed the actual accident. Both later stated that they thought Employee #1 had inadvertently released the relief valve on the jack, causing it to drop the load. The coworker who jacked up the chiller to free Employee #1's hand later stated that he had to tighten the relief valve before the pump would raise the jack.