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An unassociated failure of one part of a gyro system affected the DP system – DP undesired event

Comments from the report:

A new gyro was installed as a replacement but failed to start with first attempt. Further investigation revealed that the ‘Gyro 2 remote control unit’ located on the forward bridge had a fault, failure of it caused Gyro 2 to shut down. When the ‘Gyro 2 remote control unit’ was disconnected the new gyro was switched on with no further problems. After a stabilisation period the Gyro was tested, found operational and the signal to DP reinstated. DP operations were resumed. In conclusion the original Gyro 2 was and remains healthy.

Considerations of the IMCA Marine DP Committee from the above event:

  • It can be assumed that good operational activity planning took place and the ASOG indicated a yellow alert to be activated with the loss of one gyro
  • The logic of systems connected to the DP system need to be fully understood so that a failure in one part of a connected system does not affect the DP system
  • With the availability of so many position reference systems it may be better to use 2 DGNSS and keep the other 2 DGNSS as monitoring
  • It is unclear what the gyro 2 remote control unit is required for, but it appears to have introduced an additional failure mode of the gyro and should have been identified in the DP FMEA.

DP Event

Published: 27 February 2018
Download: IMCA DPE 01/18

Classification:
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The following case studies and observations have been compiled from information received by IMCA. All vessel, client, and operational data has been removed from the narrative to ensure anonymity.

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