The casualty described below is a good example of the importance of well-trained seafarers.
The vessel in question was equipped with four engines (of approximately 4,000 kw each) and with a diesel electric propulsion system.
When the breakdown occurred all four engines were running as normal on HFO 380 cst., and nothing unusual was noticed. Without any warning, one cylinder in one of the engines exploded. As a result, the piston rod came out of the crankcase door which again caused damage to the oil module, and a fire broke out.
Suddenly a serious situation had developed, but due to the quick reaction of the crew the HI-FOG system was activated and after 15-20 minutes the situation was brought under control and further damage was avoided. The cause of the explosion is not yet clear, the incident still being under investigation.
There is reason to believe that reduced, or lack of, oil cooling to the actual piston has caused the breakdown.
So far the investigation has shown that the piston crown in the actual cylinder split from the piston shirt, which resulted in the crankcase explosion and fire in engine room.
The explosion caused extensive damage to the engine, which led to the complete renewal of the engine block, crankshaft, piston, bearings, etc., and renewal of many electrical cables and other equipment.
No personal injuries arose from the incident, but there was significant mechanical damage that caused the vessel to stay at a shipyard for a long period, during which she was off-hire.
Quick reaction from the crew and repeated fire drills ensured that more serious damage was prevented.
The following incident occurred on a general cargo vessel.
When the incident occurred, the vessel was fully loaded and under way to a European port. The vessel was at sea, the main engine was running on full speed as normal and everything seemed to be as it should.
The engine crew only discovered that something was wrong when they noted that the main engine RPM had dropped and a bearing high temperature alarm had been activated.
Since the RPM had dropped and the main engine shaft generator was connected, a blackout also occurred at this time. The auxiliary engines started automatically and electric power was restored. However, the main engine was still running and had to be stopped manually.
The engine crew did not open the crankcase doors, but only checked the temperature on the doors, which gave no indication of over-heating. The lube oil pressure also appeared normal. After ten minutes the chief engineer decided to start the main engine again and continue the journey.
The RPM was slowly increased to full speed and it was noted that bearing temperatures increased to in excess of the permissible upper limit before decreasing again. At the same time, several lube oil filter alarms sounded. This was found to be caused by sludging.
It was decided to continue at full speed, despite all bearing temperatures being above normal, several lube oil filter alarms having been recorded, and a persisting lube oil sludging problem. The vessel continued at this speed until a crankcase explosion occurred the next morning. An automatic shutdown of the main engine was activated by the oil mist detector which was followed by heavy smoke and the sounding of the fire alarm.
Further investigation and subsequent dismantling of the components of the crankcase revealed substantial damage to the main and crank bearing. Several bearing shells were found to have been completely smashed or deformed. Furthermore, several pistons, including liners, were cracked. The engine crew quickly realised that they were unable to repair the engine and the master was informed that towing was necessary.
Upon arrival at the port, service engineers from the manufacturers attended on board and started dismantling the crankcase to facilitate further investigation. It quickly became clear that the crankshaft was bent and beyond repair. Due to the unavailability of spare parts and the consequent delivery time, repair time was estimated to be approximately 10 weeks.The investigation concluded that the most probable cause of the breakdown was the thin-walled white metal lining of one of the main bearings having broken and subsequently fallen into the crankcase. This again was the probable cause of the blocked oil supply, which led to the damage.
The crankshaft then lost its support in way of the main bearing, and this, in the end, caused the crankshaft explosion. As the crankshaft also had to be renewed, the repair time was quite extensive.
In the end we have to ask, could something have been done to prevent or reduce the damage? As can be seen above, there were several indications beforehand that something was wrong. Also, when the first warning alarm sounded, the crankshaft doors were not opened to manually check the temperature.
The lube oil alarms and the persisting sludging problem were also ignored, which again could be an indication that something was wrong.
It also has to be mentioned that the engines were running in this condition for several hours before the explosion.
The end result was very expensive for all involved, and it is strongly recommended that alarms or any indications that something is wrong are not ignored until you have satisfied yourself that everything is safe.
The majority of the cases involved engine breakdowns – some with subsequent grounding or collision and the more severe also leading to pollution or even total loss of the vessel. The risks involved in some repair or maintenance operations are not always readily identifiable. Potential risks may be overlooked due to the apparent simplicity of the work due to be carried out and the consequences may be that proper preparations are not made and the necessary precautions not always implemented.
The purpose of this circular is therefore to highlight the importance of proper planning, co-ordination and follow-up before, during and after a period of repairs.
There can be several reasons for a vessel suffering an engine breakdown shortly after a period with engine repairs. Some of the most common factors seen by Gard have been a lack of co-ordination and follow-up meetings on the progress of the repairs by the shipowner and the yard’s ship repair manager, poor workmanship and qualifications of the repairer, e.g. when using sub-contractors, and unclear allocation of responsibilities and contractual issues between the shipowner and the yard.1 Time pressure from the owner or charterer, reuse of old spare parts together with long delivery times of new spare parts or the fact that spare parts have not been ordered at all, have in many instances had a negative impact on the end result.
Modification of the lube oil system
In one Gard case the lube oil system to the main engine had been modified by the shipyard. It was later revealed that the inside of the new piping had not been treated by acid pickling and flushing to remove scale and welding remnants. Debris from the inside of these pipes was deposited in various bearings when the engines were started upon departure from the shipyard. Increasing the engine load destroyed the bearings, and caused the crankshaft pins and bearings of the main engine to overheat. The modification work was an additional task and was not part of the detailed repair specification made available to the yard prior to the dry-docking. This resulted in unclear instructions to the yard and basic elements of the installation process were overlooked. The vessel suffered an engine shut down and almost drifted ashore.
Malfunction of the thruster
In another Gard case a vessel experienced problems with the pitch on one of its thrusters. Hydraulic filters were checked and a gel-like substance was found. During analysis of the substance, plastic materials were discovered. It later became evident that the cause of the damage could be traced to the previous dry-docking period where the thruster had been serviced by the manufacturer. When the shipyard fitted the lower unit of the thruster, the protective plastic wrapped around the exposed blank steel was not removed. Over time the plastic loosened and was ground between the moving parts to small pieces of plastic which penetrated all lines and controls causing a malfunction. The incident resulted in another off-hire period in dry-dock rectifying the problem.
Fire in the engine room
In a third case the fuel pumps of the vessel’s auxiliary engines were dismounted and brought ashore for overhaul. During a routine inspection after the vessel was put to sea, the duty engineer discovered a fuel leak from one of the fuel pumps. The load was taken off the generator from the main switchboard and a normal stopping operation was carried out. During the automatic switching process from HFO to MDO the corrosion plug in the leaking fuel pump exploded, which in turn led to MDO being flushed over the exhaust channel and igniting. The burning MDO spread across the upper platform and thereafter under the floor plating. After completion of casualty inspections it was discovered that the yard had not replaced new corrosion plugs as required. No follow-up meetings on the progress of the work and quality checks had been performed during the stay at the yard.
The time available to prepare the vessel following a period of maintenance, and get her back in operation can be limited, and the refitting of removed insulation mats or spray shields is often left for the crew to complete during the voyage. According to SOLAS Ch.II-2/Reg. 4.2.2, all surfaces above 220° Celsius must be insulated or protected in order to prevent ignition by flammable liquids.2
Preparing a vessel for a period of repair or dry docking involves quite a lot of work and co-ordination for those on board, as well as for shore based staff such as fleet managers, superintendents and purchasing department. Preparation in the form of planning as well as follow up during and after a period of repair are key factors in a successful dry docking or yard stay, particularly in connection with major engine overhauls.
We would like to emphasise the following recommendations :
The risks involved in specific repair or maintenance operations are not always readily identifiable and potential risks may therefore be overlooked due to the apparent simplicity of the repair work. It is therefor recommended that a proper risk assessment is carried out prior to the repair work to ensure that sufficient preparations are made and necessary precautions are implemented.
Properly brief the engine room crew about the type and scope of maintenance to be carried out and their respective duties before entering the yard to ensure that everyone has a common understanding of the scope of work, including special challenges, critical measurements to be collected, how to correctly perform the measurements and interpret the results. Where the engine crew has not been briefed it is very difficult, if not impossible, to follow up the work carried out.
The vessel’s crew should have a certain “ownership” of the repairs and overhauls to ensure the required and sufficient quality. Regardless of who is carrying out the repair or overhaul (yard, sub-contractor or manufacturer) there should be at least one responsible person from the vessel following up each and every job.
Use the engine’s manufacturer to conduct major overhauls of main or auxiliary engines during a yard stay. Should it be necessary to use sub-contractors or the yard’s own repair teams, it is preferable to use the engine manufacturer’s representative to supervise the overhaul.
Allow sufficient time to carry out test runs or sea trials after the completion of any engine repairs. It is much more cost effective and saves time to discover problems before leaving the yard, than if a breakdown occurs once the vessel has left the yard.
To avoid misunderstandings, ensure that all involved parties have a common understanding of the contractual agreements between the repair yard and the shipowner.
Dry docking and any major repairs to a vessel are expensive for the shipowner. Many of the costly incidents and time consuming disputes could have been avoided if proper planning and preparations had been carried out prior to the period of repairs, and if the necessary test runs or sea trials had been carried out after completion of repairs.