Abstract: At approximately 10:30 a.m. on September 6, 1990, two employees were running bottom pressure tests on wells in an area. When they arrived at one field unit, they rigged an 8.5-ft lubricator in the threads of the tree-top flange on top of the crown valve of a Christmas tree. The pressure in the production tubing was measured at 711 psi and the casing or annulus at 770 psi. After measurement, the element was lowered to the 2,000-ft level for a reference stop, and then lowered again. However, pressure began escaping from the lubricator's stuffing box. Employee #1 climbed the Christmas tree and onto the lubricator. He stood on the lubricator steps to tighten the bolt on the stuffing box to stop the pressure leak. He was climbing down when the lubricator was expelled from the tree's crown valve top flange. Employee #1 was struck by the lubricator on the chest and both arms. He was pronounced dead at the scene. The lubricator had been standing on top of the Christmas tree and had only been secured by the threads on the top flange. No guy wires had been attached to stabilize the lubricator.