Comments from the report:
The vessel reported that they had changed these modules in the past whilst on DP without any issues. The risk assessment had identified that the consequence would not lead to loss of equipment greater than worst case and proceeded due to the status of the vessel operations, open water and not connected to the seabed.
Considerations of the IMCA Marine DP Committee from the above event:
- Incident validates the redundant capability of the vessel, but also potentially highlights a hidden failure leading to generator 2 failure;
- The report did not identify the root cause for the loss of equipment whilst replacing the RMP module, a successful online activity undertaken previously;
- This event highlights the benefit of considering mission equipment during risk assessments;
- It also event highlights that expected results of repairs are not always guaranteed;
- As far as is possible, maintenance or replacement of critical DP equipment should not be done while conducting DP operations;
- In this instance, it would have been prudent for ROVs to return to their TMS and the crane made safe prior to undertaking the work.