Processes for the monitoring of the exciter unit insulation resistance
Date issue released
Safety Issue Description

The processes for monitoring the condition of the brushless exciter units’ electrical insulation were ineffective in detecting deterioration prior to unit failure.

Issue number
MO-2017-003-SI-01
Issue Status
Closed – Adequately addressed
Transport Function
Marine: Shipboard operations
Issue Owner
Norwegian Cruise Line Holdings Ltd (NCLH) and ABB Industry Oy (ABB)
Mode of Transport
Marine
Issue Status Justification

The ATSB is satisfied with the action taken by ABB Oy and NCLH in response to the recommendation issued by the ATSB. 

Safety recommendation
Action number
MO-2017-003-SR-002
Organisation
ABB Industry Oy (ABB)
Action date
Action Status
Closed
Action description

The Australian Transport Safety Bureau recommends that ABB reviews the manufacturer’s instructions for monitoring the condition of the brushless exciter units used in Azipod installations. The review should incorporate findings from the examination of the failed equipment following the dry docking of Norwegian Star.

ATSB Response

The ATSB is satisfied with ongoing safety actions by ABB Oy. 

Organisation Response
Date Received
Organisation
ABB Oy
Response Status
Response Text

ABB Oy continues to conduct tests and research into failures of the exciter unit of the Azipod propulsion units. The progress on these activities is being reported eto classification society DNV-GL.

At this time no changes have been recommended to the maintenance or inspection regime for the exciter units of the Azipods. There have been no further failures of these units 

ATSB Response

The ATSB is satisfied with the action taken by ABB Oy and NCLH in response to the recommendation issued by the ATSB. 

ATSB Response date
Safety recommendation
Action number
MO-2017-003-SR-001
Organisation
Norwegian Cruise Line Holdings Ltd (NCLH)
Action date
Action Status
Closed
Action description

The Australian Transport Safety Bureau recommends that NCLH reviews the shipboard processes for monitoring the condition of the brushless exciter units used in Azipod installations. The review should incorporate findings from the examination of the failed equipment following the dry docking of Norwegian Star.

ATSB Response

ABB Oy has advised the ATSB that the investigation into the failure of the exciter unit is ongoing with ABB Oy, NCLH and the Classification Societies routinely meeting to determine the root cause of the failure.

The ATSB is satisfied with the the action taken by ABB Oy and NCLH in response to the recommendation issued by the ATSB.

Organisation Response
Date Received
Organisation
Norwegian Cruise Line Holdings
Response Status
Response Text

ABB Oy continues to conduct tests and research into failures of the exciter unit of the Azipod propulsion units. The progress of theses activities is being reported to classification society DNV-GL.

At this time no changes have been recommended to the maintenance or inspection regime for the exciter units of the Azipods. There has been no further failures of these units. 

ATSB Response

The ATSB is satisfied with the action taken by ABB Oy and NCLH in response to the recommendation issued by the ATSB. 

ATSB Response date