Abstract: Employee #1, of Fibernetics in Compton, CA, was told to finish setting up a 6 ft by 10 ft vacuum forming machine. He entered the area under the raised platen to hook up the hose at the rear of the machine to complete the set up. Employee #1 was at ground level, working on the vacuum hose, when the threaded portion of a 6 in. air cylinder shaft broke. This caused the 1,300 lb platen to drop and cock to one side. A short time later the other air cylinder, located directly across from the broken one, snapped its shaft at the threaded portion. These two air cylinders raise and lower the die platen; with both shafts broken, the platen fell, striking Employee #1. He suffered two fractured ribs and was admitted to Martin Luther King Hospital, where x-rays were taken and he was admitted for treatment. No special instructions had been given to Employee #1 regarding lockout or tagout procedures, and no precautionary measures were taken, such as blocking out the platen through mechanical means.