Abstract: Employee #1 was a tire repairman hired as a contract worker in January 1999 by Burlington Northern Santa Fe, a truck tire repair and replacement center. At 4:00 p.m. on Friday, August 4, 2000, he was in lot #12, changing a flat on the right inside rear tire of BNSF chassis BNZ 133571, at the request of a truck driver. Employee #1 asked the driver to park the vehicle near rows #1 and #2 while he went to get the proper tools for the job. He removed the valve core from the right outside rear tire, jacked up the truck, and began using a pneumatic impact wrench to remove the lug nuts. He had taken three of the five nuts all the way out when the internal pressure of the air remaining in the tire blew off the lock ring. This caused the front tire and rim to fly off its hub, striking Employee #1 in the chest and left arm with tremendous force. Employee #1 fell onto his back but remained conscious, and a coworker who witnessed the accident had him rest next to the truck. Using Employee #1's Nextel radio, he called the dispatcher and Employee #1's supervisor, who came immediately with the manager. They found Employee #1 propped up against the right front tire, holding his left arm with his right and in obvious pain. The fire department ambulance transported Employee #1 to Los Angeles County USC Medical Center, and he was later transferred to Citrus Valley Medical Center for treatment of two fractures in his left forearm. The immediate cause of the accident was Employee #1's failure to deflate the tire completely before removing the lug nuts. Truck tire repair was part of Employee #1's normal duties.