Abstract: At approximately 10:35 a.m. on April 12, 2005, a pipefitter working for Collins Timber Company was changing a sprinkler head in a hallway that served as a horizontal air duct above the humidifier in the Hardboard Plant. The employee was working alone and was using a flashlight in the darkened hallway. When the employee's wrench slipped out of his grip, he reached for it and lost his balance. He fell approximately 14.5 ft down a vertical airshaft that was directly adjacent to where he was working. The employee was not provided with a personal fall arrest system. The employee sustained bruises and soft tissue damage, and was hospitalized at Merle West Medical Center in Klamath Falls.