Learnings From Incidents (LFI) are published to promulgate learnings from incidents to enable industry to proactively manage root causes of known failures and so minimize potential for repeat DP loss of position incidents. It is recommended that owners of DP vessels disseminate LFIs to all their DP Vessel management teams, to their vendors of DP FMEAs and to their DP Technical Support Function. It is recommended that Vessel Management Teams and DP Technical Support Functions review this LFI and after a specific review provide positive confirmation to their organizations DP Technical/Quality Focal that their specific vessel designs and documentation were reviewed against this LFI and are not vulnerable to the identified or related root causes of the subject incident. Results of this investigation should be communicated back within a mutually agreed time. If vulnerabilities have been identified Vessel Management Teams and DP Technical Support Functions should communicate the initial remediation measures being undertaken along with timelines for full correction. Further information on the lessons learned or support to the business if required can be obtained by contacting the MTS DP Committee.
You may download the LFIs at no charge:
- 2015-1 - Blackout on a Segregated Power Plant
A DP 2 vessel carrying out light subsea inspection repair maintenance activities had a blackout and as a consequence had a loss of position (LOP) incident. The vessel was operating in open water and there were no consequences to people, assets or environment associated with this LOP incident. Designs with cross connections across redundant groups are vulnerable to larger failures with the potential to experience serious consequences.
Type of Incident: Power
Cause: Cross connections
DP Pillars: These illustrate the fundamentals of DP technical reliability, they are
• Fault resistance
• Fault ride through
This incident demonstrates the failure to achieve Segregation. See the MTS DP Committee Design Guidance section 3.3 for more information
- 2016-1 - External Interface with DP Station Keeping Equipment
A DP class 2 project and construction vessel suffered a position and heading excursion while conducting coiled tubing operations. The incident had no consequences to people, assets or environment. The following sequence of events was reported: • The DP system displayed a “heading out of limit” alarm and a “position out of limit” alarm.
• The vessel experienced a maximum heading deviation of 6 degree and position deviation of 4 meters.
• Bow tunnel thruster’s ramped up in response to the deviation noted on the DP system and a high force warning alarm was recorded.
• Vessel crew deselected DGNSS #1 from the DP system assuming that the excursion was caused by a DGNSS jump.
o Vessel’s crew reported that GPS “jumps” were observed on the radar an hour prior to the excursion event.
o No alarms were recorded on the DP system indicating issues with the DGNSS.
o Subsequent follow up and review of the logged data by the vendor of the DGNSS’s did not reveal any issues with the DGNSS PRS.
• Yellow limits were triggered by thruster load criteria and operations were suspended in accordance with the ASOG and vessel departed the 500 m zone.