Planned investigation resulted in DP incident
- DP Event
- Published on 18 February 2019
- Generated on 22 February 2025
- DPE 01/19
- 2 minute read
Incident
There was a total loss of network communication affecting many field stations together with loss of DP communication to all thrusters.
Comments
An AVR problem in diesel generator No.1 engine caused an over voltage in the system. Due to increased voltage, the standby machine could not be brought online, and the switchboard required a controlled blackout.
After this, many alarms from Network B were observed due to the supply being interrupted. An hour later, there was a total loss of network communication affecting many field stations together with loss of DP communication to all thrusters, which caused the vessel to drift off.
The probable cause was accidentally resetting network A, when trouble shooting of network B was taking place.
Further investigation of the overvoltage issue found a 3-phase breaker was faulty to engine No.1; the breaker was replaced by an onboard spare. The DP system manufacturer concluded that the vessel was operational as designed, indicating a possible human mistake by rebooting network A.
Considerations
It appears the DP system manufacturer responded well to this event.
The selection of “operator specified turn radius” (radio button selection) should be inhibited and “greyed out” when vessel is in a turn while move-up sub mode is active.
This inhibit function was not activated when the dialog box was opened again after the “auto – turn – move up” function had been activated. Four conditions have to be aligned for this to happen.
The “move-up” mode was introduced in 2002 and this is the first time this was reported to the original equipment manufacturer. So, the MTBF is 15-years but of course the consequence could be damage to the pipe.
A software modification has been made, installed and tested on this specific vessel. The global customer support team have a process in place to go through all software releases which have this function and update the vessels that are affected during next service visit.
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The case studies and observations above have been compiled from information received by IMCA. All vessel, client, and operational data has been removed from the narrative to ensure anonymity. Case studies are not intended as guidance on the safe conduct of operations, but rather to assist vessel managers, DP operators, and technical crew.
IMCA makes every effort to ensure both the accuracy and reliability of the information, but it is not liable for any guidance and/or recommendation and/or statement herein contained.
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