EE WAS ON THE LEFT SIDE OF THE CONTINUOUS MINER PREPARING TO INSTALL THE FIRST ROW OF BOLTS AND CHANNEL WHEN THE RIB FELL AGAINST THE VENTILATION TUBE AND THEN STRUCK HIM CATCHING HIM BETWEEN THE RIB AND THE MINER. THE RIB HAD BROKEN OFF APPROX FOUR FEET FROM THE BOTTOM AND MEASURED 10'X4'X16""