FAILURE OF CRANKSHAFT :
On a particular voyage, around 2145 hrs, the engineer’s alarm sounded. C/E entered the engine room and found the generator platform was full of oil mist. The ship was coasting near Japan, and the traffic was heavy. The duty engineer informed that he observed smoke from the running auxiliary engine and the crankcase relief valves were lifting intermittently. The standby generator was started and put on load and this generator was off loaded and stopped.
The engine was allowed to cool. Meanwhile the mustering alarm given and the fire party kept ready to fight the fire, in case if any.Lubricating oil priming pump was kept running and the engine was barred for 15 to 20 mins. Crank case was opened up and on inspection, it was found unit 5crank pin bearing sheared and the crank pin damaged beyond repairable limits. Ship proceeded to next port, and the inspections on the auxiliary engine was continued and found that out of 8 units, 7 unit’s connecting rods got bent and also the crankshaft was found bent by way of No.5 main journal.
Suspected the Lubrication failure, but gave up the idea in the sense that Low Lub oil pressure was effective and it was tried out recently. The other possibility is that the transverse frame by way of No.5 main journal might have got deformed either due to poor quality of material or defects in its fabrication.Ultimately it was found that the transverse frame got deformed, same was replaced. Line boring was carried out. All damaged connecting rods were replaced. Main bearings and bottom end bearings which were damaged were replaced with new ones. Crank shaft bend was removed and the damaged pins polished and built up. It took nearly 4 months to commission the engine.