EE WAS CHANGING A TRACTION MOTORE ON A SHUTTLE CAR. THE MOTORE WAS BLOCKED UP WITH A 4"" X 6"" CRIB BLOCK. HIS HAND WAS LYING ON HTE CRIB BLOCK WHEN A PIECE OF DRAW ROCK (10"" X 12"" X 1"") FELL FR OM THE ROOF STRIKING HIS RIGHT HAND. (3 FINGERS.MIDDLE FING CUT, FRACTURED REQUIRED PINS & STITCHES).