The ATSB is reminding ship operators and ship manufacturers of the increased operational risk of using newly designed equipment without any redundancy plan in place.
The reminder follows the release of the ATSB’s final investigation report into the loss of propulsion on the cruise ship Norwegian Star, in the Bass Strait, 22 NM SW of Cape Liptrap, Victoria, on 10 February 2017.
Shortly after entering Bass Strait, the starboard propulsion unit—the ship’s only operational propulsion unit—failed, leaving the ship without propulsion and drifting about 22 NM SW of Cape Liptrap, Victoria.
The investigation, carried out by the Victorian Office of the Chief Investigator, Transport Safety, on behalf of the ATSB under the Transport Safety Investigation Act 2003, found the ship’s port propulsion unit had been non-operational since 24 January and that the ship had sailed from Darwin to Melbourne, via Cairns and Sydney, with just the starboard propulsion unit operational.
Victorian Chief Investigator, Transport Safety, Chris McKeown said underlying factor in the starboard propulsion unit failure was a design error in the repairs it had undergone in December.
“The December repairs included a modification resulting in insufficient clearance between the brush holder and sliprings of the propulsion unit’s AC generator,” Mr McKeown said. “Despite the manufacturer’s internal quality management system, this was not identified during the review and approval stages of the design.”
We would recommend against using newly modified equipment without redundancy.
“Overall the design for the modifications was a proven and used concept, but the detailed design work required for its specific use on the Norwegian Star was not.”
“The decision to sail from Melbourne with only one operational propulsion unit was not in breach of any regulatory requirement, however, we would recommend against using newly modified safety critical equipment without redundancy,” Mr McKeown said.Last update 24 May 2018