Faulty governors

A member has reported a series of incidents involving the shutdown of two different diesel generators onboard a long term chartered vessel. On three separate occasions these incidents caused a full blackout, a partial blackout and the loss of a generator. The DP class II multi-purpose support vessel has four governors of the Woodward PG-EG58 type. During the incident investigation and fault finding process, two suspect governors were removed and replaced with two new units from a separate batch. The two suspect governors were returned to the manufacturer for inspection. The results of this inspection are summarised below:

• Broken check valves were found in the governor oil pumps of both units;
• The oil spray nozzle filters were blocked in both units. Small metal particles and pieces of check valve were identified;
• The filter in the oil line to the torque motor was blocked in both units. Small metal particles and pieces of check valve were identified;
• Foreign metal particles were found inside one of the governor units. These particles had caused the filters to become blocked, preventing oil flow to the hydraulic valve.

Although the governor can operate without the check valve, the pieces of broken valve were carried in the hydraulic system. This caused malfunction of the hydraulic valve.