Abstract: At approximately 11:00 a.m., on September 22, 2011 Employee #1 of LA County Internal Services was working with his assistant (Employee #2) to replace the bearing on the elevator #6 in the elevator mechanical room. In order to replace the bearing, Employee #1 and Employee #2 had to align all parts on both sides of the elevator drum. While checking the parts, Employee #1 accidentally hit his head onto an I-beam on the 6 feet high ceiling. Employee #2 heard Employee #1 yell and complain about the pain. Employee #1 did not have any symptoms of the injury and continued to work. Employee #1 did not report to his employer the incident that happened at the elevator mechanical room. On December 22, 2011, Employee #1 was admitted to the Woodland Hills Kaiser Hospital for brain surgery as a result of the head injury from the incident that occurred on September 22, 2011 at the elevator mechanical room. Employee #1 reported to his supervisor about his hospitalization on December 22, 2011. Employee #1 was hospitalized for one week for the surgery.