EE WAS MONITORING PROGRESS OF WASH SCREEN SHAFT REMOVAL. WHEN THE SHAFT DROPPED OUT, IT UNEXPECTEDLY SLID ALONG A HANDRAIL & CREATED A CHAIN OF EVENTS THAT RESULTED IN A URETHANE SCREEN PANEL TIPPING OVER FROM STORED POSITION. EE HAD MOVED BACKWARD & LOST FOOTING FALLING TO THE SAME SURFACE IN LINE WITH THE SCREEN TRAJECTORY. CUT RT EYEBROW.