Abstract: At approximately 7:00 a.m. on September 22, 1991, Employee #1 was starting up a steam turbine when he noticed that something was not operating properly in the steam trip throttle valve. He called his supervisor about it and they both inspected the valve. When the employee pointed with his right hand at the location where the problem was occurring, the valve mechanism slammed down and amputated the tip of his middle finger. He was taken to the Western Medical Center in Santa Ana. The supervisor said that the valve was dismantled after the accident and a spring bottom retainer was found to be broken. This caused the valve to malfunction. The employee said that he did not expect anything like that to happen. The valve, installed in 1970, suffered metal fatigue. This was the only valve of this type that was installed at the power plant. The valve was scrapped. No accident-related violation was cited.