Alert 11 – 25 Defective Clutch Results in Dropped Top Drive
While tripping out of the hole, a stand had been backed out by the Driller. The Tourpusher then relieved him to handover to his relief. With the Tourpusher running the rig, he discovered that the pipe threads had snagged. He slacked back off the stand to rotate the pipe out again. When he released the drum clutch, in order to slack off and rotate the stand, the clutch did not release thus causing the brake to loosely set. When the clutch did release, the added weight of the top drive on the brakes caused the assembly to descend. The top drive contacted the top tool joint and bowed out the stand of pipe. The Tourpusher applied the brake further, which stopped the top drive’s descent.