Lack of drills and training in procedures to be used in case of loss of steering have been identified as safety issues by Australia’s Transport Safety Bureau, ATSB, in its report on the 31 July 2008 grounding of the bulk carrier Iron King at Port Hedland, Western Australia.
The grounding followed two steering gear malfunctions on the outbound ship. After the incident a technician checked the steering gear rotary vane unit pressure and discovered that the actuator pressure was 75 bar when the rudder was turning to starboard, but only 20 bar when it was turning to port. He
determined that the aft actuator relief valve, one of two valves controlling oil pressure within the actuator, was draining oil from the actuator whenever the rudder was turning to port. As a result, the actuator pressure was being limited to 20 bar, a pressure that was insufficient to provide the torque required to turn the rudder to port when it was under load. The aft actuator relief valve was removed and the technician found that it was sticking.