Transport Malta has published an investigation report about an incident that took place on 14 September 2022. The vessel MV Mona was transiting the Aegean Sea, en route to a dry dock in Tuzla, Türkiye, when a fire broke out in the engine-room. Flames were observed rising above the main engine’s cylinder unit no. 2.
On 11 September 2022, MV Mona departed in ballast condition from the port of Ashdod, Israel, bound for a scheduled dry docking in Tuzla, Türkiye. On 14 September, the vessel was transiting the Aegean Sea, between the Greek islands, and was expected to arrive at Tuzla the next day. The voyage had been uneventful until around 1715 when, during routine rounds in the engine-room, the second engineer noticed a fuel oil leak from a slot in the fuel distributor housing of the main engine’s cylinder no. 2.
As his attempts to arrest the leak by further tightening the bolt of the housing with a spanner were unsuccessful, he used a pipe for added leverage on the spanner to tighten the bolt even further. Observing that the leak had now stopped, the second engineer wiped off the spilled oil that had collected below and left the engine-room. He proceeded to the ECR to switch the engine-room to UMS mode and then to inform the chief engineer about the leak during dinner time in the mess room.
At 1730, however, just as the second engineer arrived in the ECR, the fire alarm activated for the engine-room. At about this time, the second engineer also observed a low-pressure alarm for the main engine’s cylinder unit no. 2, on the ECR control panel. Opening the door to the engine-room, he saw high flames and dense smoke rising from cylinder unit no. 2. He shut the door and ran back to the ECR, while raising a verbal alarm on the fire.
In the meantime, the chief engineer was on his way to the messroom. Hearing the alarm, he rushed to the ECR, where he met the second engineer, who told him about the fire. The chief engineer opened the engine-room door and saw the fire for himself. At 1733, before the chief engineer could stop the main engine from the ECR, the vessel lost all power. He instructed the second engineer to immediately shut off all fans, dampers, ventilation, and electric supply to the engine-room, following which, he rushed to activate the quick-closing valves.
The fuel distributor manifold (item no. 3: choking tube; item no. 6: expansion joint; item no. 8: fuel distributor housing; item no. 9: bolts for the fuel distributor housing; item no. 17 bore holes; item no. 20: fuel feed pump)Meanwhile, on hearing the fire alarm from his cabin, the master ran up to the bridge. Noting that the fire alarm panel indicated that the fire was in the engine-room, he ran back down to the engine-room, where he came across the chief engineer who was activating the quick-closing valves. The chief engineer briefed the master about the situation before the latter returned to the bridge. He advised the chief officer, who was the officer of the watch, to have all crew members mustered and the fire team ready to fight the fire in the engine-room. He subsequently notified the Company via the satellite telephone.
By 1739, the rest of the crew members had mustered at the muster station. Following the chief officer’s instructions, the bosun and the oiler donned fire-fighting outfits and self-contained breathing apparatus (SCBA) sets. At 1741, the bosun and the oiler entered the engine-room with foam and carbon dioxide portable (CO2) fire extinguishers. Unable to control the fire, they retreated and advised the chief officer, who relayed the message to the master on the bridge.
The master went down to the upper platform of the engine-room to assess the situation. From there, he observed high flames and dense smoke. He left the engine-room and instructed the crew members to prepare for the activation of the vessel’s fixed CO2 fire extinguishing system for the engine-room and to stand by for his orders. He then went back to the bridge, updated the Company on the situation, and of his intention to activate the fixed CO2 fire extinguishing system to extinguish the fire in the engine-room. He also contacted the Greek authorities, notified them about the fire on board, and provided them with an update on the situation.
Once the crew members confirmed that all preparations were in place for the activation of the fixed CO2 fire extinguishing system, the master instructed the chief engineer and the chief officer to activate the system. At 1809, the fixed CO2 fire extinguishing system was activated. Soon after, the crew members observed a reduction in the smoke density.
By 1958, the vessel had drifted closer to the Northwest coast of Chios and having consulted with the local authorities, the crew members dropped the vessel’s starboard anchor. The master then instructed the crew members to carry out fire patrols and temperature checks of the area around the engine-room, in shifts.
It was during a discussion between the chief engineer and the second engineer when the latter informed the chief engineer about the leak he had observed, prior to the fire alarm, and his actions to eliminate it.
Cause of the fire on board MV Mona
Based on the crew members’ narratives and the observed fire pattern, the safety investigation concluded that the fire was caused by a spray of fuel oil from the region of the main engine’s cylinder units nos. 1 to 3 onto hot surfaces in the vicinity.
Probable cause of the fuel oil spray
In view of the heat and smoke damage to the main engine, the safety investigation was unable to determine the exact location from where the fuel oil sprayed out and ignited. Nonetheless, the broken bolt of the fuel distributor housing, of cylinder unit no. 2, strongly suggested that the oil may have sprayed out from this area. Once broken, oil would have sprayed out from the housing.
Probable cause of the fuel oil leak
The spray of fuel oil from the fuel distributor housing, in turn suggested a leak in the choking tube(s) of the fuel distributor for cylinder unit no. 2 and / or the feed pump’s connection to the fuel distributor housing. It is possible that the second engineer may have not been aware that the leak may have originated from the aforementioned parts.
The safety investigation hypothesized that the cause of the oil leak could be attributed to:
– failure of the choking tube(s), and / or
– excessive tightening of the fuel distributor housing bolt, leading to damage to the fuel feed pump casing.
Failure of the housing bolt aboard MV Mona
As mentioned earlier in this safety investigation report, the main engine’s manual specified a torque of 130 Nm for the tightening of the housing bolts. The second engineer had used a spanner with a pipe for extra leverage to tighten the bolt from where he observed an oil leak. He had no indication as to the torque being applied to further tighten the bolt.
Although the damaged threads of the bolt suggested failure due to over tightening (Figure 10), the safety investigation requested the Company to provide it with the broken bolt for the purposes of laboratory tests. These tests would have assisted the safety investigation to determine the cause(s) for the breakage of the bolt. However, the Company advised the MSIU that the broken bolt was held by the vessel’s insurers and was therefore unavailable.
The denied access to the broken bolt not only has compromised a detailed analysis of the failure mechanism of the bolt but prohibited it altogether. To this effect, the MSIU was unable to contribute towards a technical analysis and therefore on how the repeat of such an accident can be prevented.
In view of the above, the safety investigation can only suggest that the applied extra torque may have exceeded that specified in the manual and resulted in the failure of the bolt.
Conclusions
– The safety investigation believes that the fire was caused by a spray of fuel oil from the region of the main engine’s cylinder units nos. 1 to 3, onto hot surfaces in the vicinity.
– It is likely that oil sprayed out from the fuel distributor housing of cylinder unit no. 2 after the bolt failed.
– The bolt which failed had been tightened by the second engineer, using a spanner and a pipe for extra leverage on the spanner without an indication of the torque being applied.
– The manual for the main engine, which contained the torque limits for the bolts of various components, was not available on board.
– The safety investigation was unable to determine the exact cause of the breakage of the fuel distributor housing bolt, as it did not have access to the broken bolt. This not only has compromised a detailed analysis of the failure mechanism of the bolt, but prohibited it altogether.
Lessons learned after MV Mona fire
Following this occurrence, the Company advised all crew members on board its fleet of vessels to:
– notify the masters and chief engineers, prior to carrying out any maintenance tasks on critical equipment;
– use appropriate equipment for the maintenance of critical equipment;
– ensure that an officer confirms that all parts of all equipment on board are working properly; and
– stop the main engine, if necessary, to carry out maintenance tasks on fuel pumps and lines.
