• Published: 12 May 2011
  • Incident ID: 3106

Uncontrolled extension of Top Drive Link Tilt

Cause & Consequence

  • Moving, flying or falling object
Incident Consequence

Incident Location

Drilling unit

Incident Activity

Drilling, workover

Specific Incident Equipment

No details available.

Lessons Identified

Failure of company Management System to capture and retain industry lessons learnt.Accepted practice in attaching the rope to the link tilt intermediate stop to the bail arm.Pneumatic operated link tilt system inherently fail-unsafe:When the link tilt is extended to the intermediate position, the link tilt bellow charges to full pressure against the intermediate stop. If the intermediate stops are rendered ineffective the link tilt will extend fully with force and speed.

Incident Recommendations

Remove the rope attached to the link tilt intermediate stops when it is not required. Equipment connected to the link tilt system should not be connected to the bail arm, with the exception of the link tilt chains. Review the design of the link tilt system with the manufacture to seek a fail-safe system.

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