Two loose dowel pins and poor shipboard communications led to a contact incident of BC Ferries Queen of Nanaimo on 3 August 2010, says an internal company report obtained through the Freedom of Information Act by the Vancouver Sun.
The incident, in which the vessel hit a dock at 5 knots, resulted in four injuries to passengers and six to employees.
Each of the vessel’s two controlled pitch propeller arrangements include two tapered dowels which secure the auxiliary servo piston and the lever on top of the Kamewa control post which moves the valve rod for the propeller hub. After the incident the two dowels in the port oil distributor box were missing.
Without the dowels there was a disconnect that resulted in the CPP drifting to full ahead. Indicators on the bridge and in the engine control room would have shown the propeller as ‘adrift’ with almost zero pitch on the port shaft but was not noticed.
Neither the engine room nor the bridge realised that the port propeller had failed to full ahead. Communications were hampered by the lack of a talk-back system between the bridge and the engine room.
There were two thing wrong with the dowels, those on the port side were the wrong dowels and the locking nuts that might have kept them in place had not been fitted. Those on the starboard side were correct and fitted with lock nuts. There was no note in maintenance records. The appearance of the failed port dowels was significant enough from those on the starboard system to indicate that they were the wrong type and not properly fitted.
BC Ferries has told its engineering staff that critical components must be inspected during and after refit or repair and a quality assurance system should be introduced.
The incident exposed a number of shortcomings that may have developed over time and poor procedures that had become standard operating procedures.
MAC considers the BC Ferries investigation a good example for internal investigative report which should be encouraged. It concentrates on fixing the problem, not the blame.