What happened

When the operating levers was put forward to bring the vessel to the dock, the crew felt that something was wrong and that the engine increased speed and was out of control for the crew. The levers were then immediately taken back to zero position in an attempt to regain control, but this did not give the desired effect, and the vessel continued forward.

They pressed the emergency stop button, and the crew lost control of the vessel that now was without engine power. The vessel continued a few tens of meters before it hit several pleasure crafts and the dock. The incident led to significant damage to dock and pleasure crafts.

Cause

Prior to the incident, the vessel had been to service where it was carried out work on the operating system. They ran tests afterwards and everything worked as it should at the time.

When the vessel had new service after the accident described above, it was discovered several new errors related to the actuator. A loose splint to the drive shaft / actuator and misaligned actuator, led to the possibility to have error on both pitch actuators simultaneously.
The detected errors were probably the cause of the accident. When the fault occurred and because the vessel were near the dock, there was not enough time for the crew to run emergency steering from the engine room.

What we see

Norwegian Maritime Authority have seen that equipment are modified or equipment get new requirements or practices relating to the use, maintenance, and operation. Findings after the above-mentioned accident showed that the equipment on board had been modified after it was installed on board the first time. Changes was carried out on the control system, without drawings and documentation showing the changes.

Claim

By including periodically unattended machinery (UMS), must also the recognized classification society's requirements for periodically unattended machinery be followed, this also includes manoeuvre, control and monitoring equipment. When changes are made on the aforementioned equipment, this must be documented and described in the system manuals and procedures. Routines that have to be changed as a result of equipment changes must be taken into the daily operation and be known to all those who use the equipment.

“Approved, type-approved or accepted” as described in Regulation, requires that equipment changes retain its original characteristics also after the change.

Changes must be documented.

If doubt it will always be necessary to evaluate whether a new approval is required.

  • Approved: a single piece of equipment approved by the Norwegian Maritime Authority, with the exception of radio equipment approved by the Norwegian Post and Telecommunications Authority.
  • Type-approved: prototype approved by the Norwegian Maritime Authority with or without spot checks of mass production.
  • Accepted: equipment accepted by the Norwegian Maritime Authority on the basis of approval or type-approval by a recognized classification society, any other public or private institution, or the administration of a country which has ratified the SOLAS Convention.

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Footnote

An actuator is a type of motor that is responsible for moving or controlling a mechanism or system.

It is operated by a source of energy, typically electric current, hydraulic fluid pressure, or pneumatic pressure, and converts that energy into motion. An actuator is the mechanism by which a control system acts upon an environment. The control system can be simple (a fixed mechanical or electronic system), software-based (e.g. a printer driver, robot control system), a human, or any other input.

Reference: https://en.wikipedia.org/wiki/Actuator