Cause & Consequence
- Fall from height
Causes and key findings
■Uncontrolled descent of CT injector and BOP's within the CT lift frame.
■Suspected CTLF main winch Failure.
■IP was man riding on lower part of CTLF to guide BOP stabbing operations.
■IP man riding winch wire became entangled in descending CT BOP, which pulled the IP off the lift frame.
■Man riding winch overloaded and wire unspooled due to winch cable snagging on BOP's and injector head.
■Worksite was made safe, Senior Onshore Management team mobilised to site to commence investigation.
■Investigation a collaboration between Aker Qserv, rig owner/duty holder and client and remains on-going. S.I slide will be fully updated to reflect conclusions and lessons learned on completion of investigation.
■Winch was returned onshore for testing and strip down to determine failure. Tests conducted and reviewed with winch provider and third party independent.
■Initial findings point to failure of primary failsafe brake
■Secondary method of load control failed due to hydraulic system pressure inadequate to provide continual replenishment of hydraulic oil to the motor and counterbalance valves thus starving the motor/counter balance of oil. This allows the load to drop at a high rate causing cavitation within the motor while the system is in neutral.