Last month, I wrote about using condition-based maintenance to prevent unnecessary maintenance costs. Not spending valuable resources on replacing or overhauling equipment that may still work perfectly, based purely on a maintenance schedule makes good business sense when combined with condition monitoring and testing. Without the monitoring and testing, condition-based maintenance becomes lack of maintenance, and can be quite disastrous. The following is a good reminder of that.
Last week, the UK Marine Accident Investigation Branch released its report (no. 22/2015) on the investigation of a major engine room fire on board P&O Ferries’ passenger ferry, Pride of Canterbury. The incident took place while berthing in Calais on 29 September of last year.
According to the report, one of the propellers became unresponsive and was shut down during the approach to Calais. It was deemed safe to continue without the propeller and the system was started up again, using the defective propeller’s stand-by pump to maintain oil circulation. It didn’t take long for a joint in the pipeline to burst, spraying hydraulic oil onto the exhaust uptakes. The heat from the exhaust ignited the oil immediately, starting a fire in the main engine room. The engine room was evacuated and the passengers were gathered at the emergency stations. The fire was extinguished and the ship was unloaded normally in Calais.
The cause of the incident turned out to be a defective back pressure valve in the hydraulic system which had jammed shut, prompting a rise in oil pressure in the return line. One of the joints in the return line ruptured under the pressure, spraying the exhaust uptake with oil in the process.
As it turns out, the defective valve had been in service for 23 years, but had not once been tested for functionality during that time. The manufacturer had specified an annual test interval, but did not specify how to conduct testing. This unfortunately resulted in the valve not being tested at all and, upon the valve’s failure, sparked a chain reaction of events that could have ended much worse.
In this case, the fallout was limited to material damage. The incident led to modifications to the propeller systems, and procedures have been set in place to prevent similar accidents in the future. Nevertheless, an event like this does emphasize the importance of maintenance being carried out, but also that manufacturers should specify exactly how and when it must be carried out.