Executive summary
On Thursday 21 November 2002 at about 0938, the bulk cement carrier "Westport" collided stern first with the Old Mangere Bridge when the controllable pitch propeller mechanism failed during departure from Onehunga. Both the ship and the bridge suffered extensive damage.
The safety issues identified included:
· the adequacy of knowledge of default conditions for the system
· the adequacy of knowledge of correct operating pressures for the controllable pitch propeller.
Safety recommendations were made to the General Manager of Holcim (New Zealand) Limited to address the safety issues.
Related Recommendations
Ensure that all the crew of the Westport who are responsible for the operation, maintenance and monitoring of the controllable pitch propeller system are made aware of the way the system defaults under differing failure conditions and the necessary corrective action to take in case of a failure.
Instigate regular monitoring and logging of the critical operating oil pressures and flows of the controllable pitch propeller system under repeatable standardised operating conditions. Ensure that data collected is understood by the engineers and is sufficient to give warning of a possible failure in the unit. The maintenance system of the vessel should include the action to be taken if the values obtained deviate from those specified by the manufacturer.