Following a steering failure, which caused the tanker Bow Singapore to ground in August 2016, the Australian Transport Safety Bureau (ATSB) highlighted the need for a well-formulated maintenance plan.
The 2004-built oil tanker ran into trouble on August 19 outside Australia’s Geelong harbour after its steering gear ceased working and the rudder 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.
ATSB’s investigation revealed that Bow Singapore’s A telemotor solenoid, controlling the rudder’s movement to starboard, had stopped responding to electrical signals, which initiated an uncontrolled turn towards the edge of the channel and shallow water.
“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 officials noted.
The planned maintenance system for the steering gear did not include or contain any schedules for any 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.
Bow Singapore was re-floated on August 20, with the assistance of the rising tide and a tug. The ship proceeded to anchor and, later, to the discharge berth in Geelong. After discharging cargo the hull was inspected by divers and no damage was found.
Odfjell Management, the ship’s managers, arranged for a replacement of the solenoids and shuttle valves for both steering systems, while the relief valves were opened and examined and the oil was changed. No faults that could cause the failure were found.
ATSB said that the ship managers have now included a 6-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 colours 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.