GOVERNOR-AIR CYLINDER LINKAGE FAILURE
The vessel with Main Engine 6RTA 58 was fully loaded, the sea was very rough, with the vessel pitching heavily; the time was about 3AM and I was in the 12/ 4 watch.
I was taking rounds in the purifier room when suddenly the junior engineer came running and told me that the cylinder relief values were lifting. Due to the noise from the two running purifiers I had not heard the noise from the main engine. At once I rushed to the engine control room and found that the main engine over-speeding. I attempted to stop the ME by turning the fuel lever to zero, but I found there was only slight change, so the emergency stop button was pressed to bring the main engine to stop. The bridge was informed and so also the chief engineer.
On investigation later we found that the pin connecting the air cylinder linkage to the governor had come out and the linkage had come to rest against the panel for engine parameters; and so the over speeding was limited to some extent. The locking of the pin was worn out due to the fact that the load on the engine was fluctuating heavily, and the governor kept trying to bring the speed within limits. So the violet movement of the linkage has caused the pin to slip out.
We at once put the linkage in place and locked the same from both sides with bent tin sheet. All the crank case doors were opened up to have a thorough check of the crank case and the locking. #4 after web of this main engine had suffered a slip of about 3° before a year or so. I examined the web for any further slippage and also examined the other marks on the other webs. Fortunately we found every thing in order. The doors were boxed back and the main engine was blown through by air and started on fuel, then slowly first, and progressively the speed was increased. All cylinder head relief valves were OK, and by about 7 am the main engine was put to full speed.