Norway's Transportation Investigation board has released a preliminary report on this accident. You can find it attached.
Here's a rough translation....
Lillestrøm, 20 October 2011
AIBN (AIBN) has implemented safety investigation in connection with the fire on board the coastal steamer Northern Light 15 September 2011. Thurs crew members were killed and two were seriously injured during the fire, which occurred in the main engine room during the approach to AES. Seven crew members were slightly injured. Northern Light had 207 passengers on board. All were evacuated without any physical injuries.
Accident Investigation Commission's work has so far included technical surveys on board, review of logs and other forms of documentation, and interviews with the crew and other involved parties. There is also conducted laboratory studies of various machine components. AIBN has in this connection, factors that may have been crucial in both the cause and course context.
AIBN want to notify the NMD as a supervisory authority of the safety critical conditions AIBN already looks to have affected the accident.
1. PRELIMINARY OBSERVATIONS
1.1 Diesel Leaks at the starboard main engine
The investigations of the main engine room after the accident shows that there has been heavy fire in and around the starboard main engine. The fire was at its strongest around the anterior part of the starboard side of the engine. Molten aluminum parts and deformed steel structures shows that there has been very high temperatures in this area.
The main engines on board the Northern Lights are two six-cylinder diesel engines of the type MaK 6M552C providing 6,114 hp (4500 kW) each. Accident Investigation Commission's examination of the engine room after the accident has also focused on possible leaks of flammable liquids, and in this connection were made observations of particular interest. The observations are mainly related to the fuel system of the starboard main engine. The picture below shows the starboard side of the starboard main engine front and aft. The findings, which are further described below, is marked in the picture.
Figure 2: The photo shows the starboard side of the starboard main engine front and aft.
1) Fuel Pump # 5
2) Fuel Return, drains
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At the Board's investigation it was discovered violations in low-pressure pipe leading fuel in return from the fuel pump for cylinder No. 5 (numbered from stern). The breach was discovered by welding to the upper flange (see Figure 3).
During removal of the tubes was also uncovered violations in the supply pipe and the oil pipe that leads to the oil pump. It is not clear whether the break in the conduit occurred during disassembly or whether it was already broken, the insulation material may have hidden a break. Probably the pipe was about to fail and can therefore be broken during disassembly. The tubes are sent to the metallurgical examination of the analysis. The preliminary results indicate that in the case of fatigue fracture.
1) Fuel Pump # 5
2) Stir the return from the pump
3) Stir for supply to the pump
4) Violation of the pipe for the return
5) Fixing Bolts for fuel pump
In addition to the investigation uncovered violations in both fuel pipes and the oil pipeline, the bolts fastening the same fuel pump # 5 was found to be so loose that they could be disassembled by hand. According to the engine manufacturer's maintenance manual to the bolts tightened with torque to 190 Nm. The fuel pump was replaced 12 days before the fire occurred. The job description of the ship's maintenance system does not mention explicitly torque and show not to the maintenance manual or other supporting documentation.
AIBN is working at present from a theory that the loose bolt caused the fatigue fractures in the fuel pipes and oil pipe. After the fire, it was found that the fuel pump could move around. 2-3mm from the surface as a result of the bolts were loose. At each revolution of the camshaft, the whole pump could be pushed upward by the comb. Such a movement will cause low pressure pipes cyclic stresses. Accident Investigation Board will look into the fuel system in the further investigation.
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Another key observation is related to the fuel pipe for returning fuel from the cylinders. Fuel pipes discussed above, with the return from each cylinder, collected in a common pipe leading the fuel back to a tank. This handset comes starboard side and goes down in front of the engine. Here it is mounted a T-connector with a drain pipe that has been closed with a ball valve and a threaded plug (see Figure 4). Accident Investigation Commission has been informed that this tube has probably been intended for a drainage function, but that probably has never been used. The survey was only Threaded left on the tube. The second part of the valve, the ball and the plug was found nearby. Fire is the lowest point seems to have been in this area.
Figure 4: The picture on the left is from the starboard main engine of the Northern Lights and displays the drain pipe with ball valve and plug, and the image on the right is from the starboard main engine of the Northern Lights and displays the drain pipe with only Threaded place.
Following the Board's view it is highly unlikely that the two violations of the fuel system have occurred simultaneously and independently. One can therefore assume that one leak has occurred first, created a primary fire, and then caused the second breach in the fuel system which, in turn, has further contributed to the fire. AIBN is working out the theory that low-pressure pipe for the return of cylinder No. 5 has cracked first as a result of fatigue and that the fuel leak quickly reached an ignition source (see Section 1.2 below). Further investigation will look into the fire development and the relationship between the two leak points.
1.2 Hot surfaces - potential ignition sources
Several of the indicator cocks on the starboard engine was found inadequate in isolation. These taps are connected top of the cylinder in order to diagnose metabolism through measurement of cylinder pressure. Indicator The cranes will be able to reach temperatures over 220 degrees Celsius, and will thus normally be isolated. A spray of diesel hitting a hot surface will cause a fire. The nearest bar faucet without adequate insulation were less than 30 cm from the tube with the breach. Measurements made on board the sister ship Richard With shows that this indicator taps at temperatures around 270 degrees during normal operation.
A Regulation of 28 March 2000 No. 305 concerning surveys, construction and equipment of passenger ships in domestic trade, Annex 1, Chapter II-2 and DNV Rules for Ships January 2011, Pt. 7 Ch.2 Sec.2 C203
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Figure 5: The picture on the left shows indicator valve between the cylinder No. 4 and No. 5 cylinder on the starboard main engine and the distance to the fuel pump No. 5 (the tubes are removed). Indicator crane was found uninsulated. The picture at right shows imaging of the corresponding indicator crane aboard Richard With. Photo right Photo: SINTEF NBL.
1.3 Ventilation and cooling of nødgeneratorrommet
Under fire in the engine room of the systems were the main power quickly put out of action. The investigations so far indicate that the emergency generator when started as it should, and provided power to the ship's emergency systems. After a short time, probably about 20 minutes, failed the emergency generator.
The investigations on board the dampers to ensure that the emergency generator has access to fresh air for cooling and combustion found in the closed position. It was also found violations of a coolant hose. Lack of air around the radiator to cool the cooling water has probably led to such high temperatures and pressures that the chilled water pipe has burst. With the complete lack of cooling the engine quickly become so hot that it has cut down and stopped. Preliminary examination of the engine to support this theory, and there are no findings on the engine that would indicate that it has stopped for other reasons.
Figure 6: The left photo shows the aft damper to the emergency generator outside. The photo shows the starboard dampers inside nødgeneratorrommet.
The above-mentioned flap is designed so that they are kept open by means of compressed air. The compressed air comes from the working air system, which relies on a compressor that is associated
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main power system. This was pointed out that a weakness in the Board's report (SEA 2010/03) after the grounding of the sister ship Richard With. After the incident, it was fitted with a valve that was meant to prevent unwanted closing of the louvers. This valve had been installed on board the Northern Lights before the fire. However, had the crew aboard the Northern Lights during testing found that the system still did not work satisfactorily in relation to the accidental closing of the vanes. It had therefore been ordered parts for further improvements, but these had not arrived and assembled when the accident occurred. In conversations AIBN has had with the crew, it emerged that after the fire occurred was attempting to reach nødgeneratorrommet to ensure the air supply. This failed because it was too thick smoke to get around in this area.
2. SAFETY CRITICAL ISSUES
Based on the above observations will AIBN with this alert authorities of the following safety critical conditions:
Notification of safety-critical conditions No. 5 / 2011 SHT
After the fire at the Northern Lights, it was found a fuel pump with loose mounting bolts and breaking the fuel and the Engine oil to the same pump. The loose bolts have apparently caused the cyclic stresses and fatigue fracture in the above tubes, which in turn has led to fuel leakage.
Notification of safety-critical conditions No. 6 / 2011 SHT
It is found more inadequate isolated areas on the main engines on board the Northern Lights. These are areas that the operation will be able to reach temperatures above 220 ° C, and thus should have been isolated. Accident Investigation Commission considers it very likely that the above mentioned fuel leak has reached such hot surfaces and thus triggered the fire.
Notification of safety-critical conditions No. 7 / 2011 SHT
Under fire in the engine room of the systems were the main power quickly put out of action. Emergency generator, which then provide power to the ship's emergency systems, failed after a short time. The investigations on board the dampers to ensure that the emergency generator has access to fresh air for cooling and combustion found in the closed position. This has probably caused the engine to quickly has become so hot that it has cut down and stopped.
3. FURTHER WORK
Accident Commission will continue to examine the relevant issues surrounding fuel leaks at the starboard main engine. It is also found that it lacked the covers before the fuel system on both the main engines on board the Northern Lights. The effect of these was lost will be considered further. There will also be conducted a comprehensive survey of hot surfaces in the engine room.
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Furthermore, the Commission will work to assess the extent and consequences of the fire, including how the fire control system worked and the extent to which smoke had spread. In addition to CO2 - based fire extinguishing systems had Nordlys a water-based fire control point system in the engine room. The preliminary investigation indicates that the water-based extinguishing system was triggered during the fire. CO2 - the facility, if any, must be released manually, was not released because it was not accounted for all crew members.
Accident Investigation Commission intends to prepare a report within a year after the time of the accident, which explains the events and the Board's assessments of the causes. The report will include any recommendations for action to be taken or considered with a view to preventing similar accidents in future.
- Nordlys preliminary report.pdf
- MV Nordlys engine room fire preliminary report by Norwegian accident investigation board
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