EE WRAPED HIS FALL PROTECTION LANYARD AROUND A DIAGONAL WIND BRACE & CLIMBED TO THE TOP OF IT TOTHE NEXT LEVEL OF THE PREHEATER STRUCTURE (~20')AS HE ATTEMPTED TO CLIMB UP ONTO THE FLOOR FOR T HAT STRUCTURE LEVEL HE LOST HIS GRIP, FELL BACK,AND BEGAN SLIDING BACK DOWN THE BRACE. HE FELL ~8' LANDING ON RIGHT FOOT.