Steering Failure Highlighted Maintenance Problem
The Australian Transport Safety Bureau (ATSB) has released its investigation report into the grounding of the tanker Bow Singapore in Port Phillip Bay, Victoria, in August 2016, highlighting both procedural and maintenance issues as contributing to the accident.
On August 19, 2016, a Port Phillip Sea Pilot boarded the vessel. The pilot was to conduct the ship through The Rip and the South Channel to an anchorage in the northern part of Port Phillip.
As the ship neared the eastern end of the South Channel, the rudder ceased responding to helm inputs and remained at 5° to port. The ship started swinging towards the edge of the channel. Steering was regained a short time later but, despite the efforts of the pilot, the ship grounded. The ship was re-floated the next day and did not sustain any hull damage.
A telemotor solenoid, controlling the rudder’s movement to starboard, had stopped responding to electrical signals. The company’s procedures for a steering gear failure required a change in operation from the bridge to local emergency operation from the steering gear room. However, the procedures did not include the steps to be taken on the bridge prior to that change, such as using non follow-up mode and changing to alternate telemotor and/or pump systems.
The planned maintenance system for the steering gear did not include any schedules for detailed inspections or scheduled parts replacement. In addition, the hydraulic system port and starboard solenoids were painted green and red respectively, to match the side of the ship that each is on when mounted on the shuttle valve. However, this was opposite to the direction the rudder would move when they were operated.
Odfjell Management, the ship’s managers, arranged for a manufacturer’s representative of the steering gear to attend the ship when it arrived in Singapore. The solenoids and shuttle valves for both steering systems were replaced, the relief valves were opened and examined, and the oil was changed. No faults that could cause the failure were found.
The ship managers have now included a six-monthly job entry into their planned maintenance system for the opening and inspection of the steering gear’s solenoids. In addition, the telemotor solenoids have been repainted so that the colors now match the direction of rudder movement, rather than the side of the ship on which they are mounted.
Further, the fleet wide safety management system procedure for steering gear failure has been amended to include reference to ship specific emergency change over procedures.
The report is available here.