MAIN ENGINE BREAKDOWN
12th Jan. 06
With the ship heading towards Haldia lock gates with Pilot on board, suddenly exhaust gas temperature of # 4 unit of Main Engine (B&W 6L60 MC) shot up very high.
We checked fuel pump fuel regulating shaft for functioning and found the fuel rack free and operating well.
After this fuel rack was pulled back to reduce the amount of fuel being injected into the system. With temp still not coming down, and ship entering lock gates the Pilot didn't allow the engines to be stopped for checking the reasons for the temp increase.
After this a heavy knocking and banging noise was heard near the No. 4 unit Ext valve. This noise gradually increased and was heard throughout the full length of the unit from Exh. V/V to crank case. Very little Engine movements were given after this.
After berthing, engine under piston space opened and found liner had broken into two halves at the scavenge ports.
The Broken Cylinder liner piece was lying on the diaphragm. The V/V was removed and found a part of the spindle broken, this piece having fallen and come in between the piston and liner scavenge port.
During upward movement of piston the liner was damaged.
This particular V/v spindle had been reconditioned more than 3 times- i.e. by building up parent material, coating and then machining.
But as per B&W, V/v spindles should not be reconditioned more than 2 times. So as the actual parent metal had been removed in due course, reconditioning had resulted in spindle material loosing its strength and eventual breaking of the V/v spindle.