BitDullCode These values represent a classification of a drill bit based on its reason for being declared inoperable, as originally defined by the IADC. BC - Broken Cone BT - Broken teeth/cutters BU - Balled Up CC - Cracked Cone CD - Cone Dragged CI - Cone Interference CR - Cored CT - Chipped Teeth ER - Erosion FC - Flat Crested Wear HC - Heat Checking JD - Junk Damage LC - Lost Nozzle LN - Lost Nozzle LT - Lost Teeth/Cutters NO - No Dull/No Other Wear OC - Off-Center Wear PB - Pinched Bit PN - Plugged Nozzle RG - Rounded Gauge RO - Ring Out SD - Shirttail Damage SS - Self-Sharpening Wear TR - Tracking WO - WashOut on Bit WT - Worn Teeth/Cutters unknown The value is not known. This value should not be used in normal situations. All reasonable attempts should be made to determine the appropriate value. Use of this value may result in rejection in some situations.