Podcast
Questions and Answers
What was the primary factor that led to the mechanical failure of the no. 3 main engine?
What was the primary factor that led to the mechanical failure of the no. 3 main engine?
- A failure in the fuel injection system causing uneven combustion.
- The installation of an incorrectly sized main bearing during a previous overhaul. (correct)
- Overheating of the engine due to a malfunctioning cooling system.
- Normal wear and tear on the engine components, exacerbated by prolonged use.
The incorrectly sized main bearing primarily led to which of the following immediate consequences?
The incorrectly sized main bearing primarily led to which of the following immediate consequences?
- Increased friction and wear on the crankshaft.
- A reduction in fuel supply to the engine.
- Elevated exhaust gas temperatures.
- Leakage of lubricating oil and subsequent drop in oil pressure. (correct)
What was the direct result of the loss of lube oil supply pressure to the connecting rod journal bearings?
What was the direct result of the loss of lube oil supply pressure to the connecting rod journal bearings?
- Increased vibration throughout the engine block.
- A decrease in engine RPM and eventual stall.
- A surge in electrical power generation from the engine.
- Rapid temperature increase in the connecting rod bearings and fracturing of bearing cap bolts. (correct)
Which of the following actions taken by the crew was most critical in preventing the fire from spreading?
Which of the following actions taken by the crew was most critical in preventing the fire from spreading?
Besides isolating fuel and stopping the engines, what other action did the crew take to control the fire by removing a key element?
Besides isolating fuel and stopping the engines, what other action did the crew take to control the fire by removing a key element?
What specific system did the crew activate as a final measure to extinguish the fire?
What specific system did the crew activate as a final measure to extinguish the fire?
What is the most important lesson learned from this incident regarding machinery maintenance?
What is the most important lesson learned from this incident regarding machinery maintenance?
To prevent similar incidents, what type of system is recommended for tracking replacement parts?
To prevent similar incidents, what type of system is recommended for tracking replacement parts?
What was the primary cause of the fire on the offshore supply vessel, according to the safety flash?
What was the primary cause of the fire on the offshore supply vessel, according to the safety flash?
Why was the no. 6 main bearing replaced with a standard-sized bearing during the maintenance period?
Why was the no. 6 main bearing replaced with a standard-sized bearing during the maintenance period?
What was the estimated financial impact of the engine failure on the offshore supply vessel?
What was the estimated financial impact of the engine failure on the offshore supply vessel?
Which factor most directly contributed to the technicians' error in replacing the no. 6 main bearing?
Which factor most directly contributed to the technicians' error in replacing the no. 6 main bearing?
What operational phase was the offshore supply vessel in when the engine failure occurred?
What operational phase was the offshore supply vessel in when the engine failure occurred?
What immediate action did the crew take after the mechanical failure and fire?
What immediate action did the crew take after the mechanical failure and fire?
Why is the NTSB’s 'Safer Seas Digest 2023' relevant to IMCA members?
Why is the NTSB’s 'Safer Seas Digest 2023' relevant to IMCA members?
What load conditions were present on the vessel's systems at the time of the engine failure?
What load conditions were present on the vessel's systems at the time of the engine failure?
Flashcards
Engine Room Fire Cause
Engine Room Fire Cause
Mechanical failure of a diesel generator engine leading to a fire.
Incident Context
Incident Context
Offshore supply vessel, post-maintenance sea trials.
Root Cause
Root Cause
Incorrectly sized bearings were installed during maintenance.
Incident Cost
Incident Cost
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Service Company Practice
Service Company Practice
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Incident Result
Incident Result
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Sea Trial Purpose
Sea Trial Purpose
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Missed Part Number
Missed Part Number
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Root cause of engine failure?
Root cause of engine failure?
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What was a direct result of the incorrectly sized bearing?
What was a direct result of the incorrectly sized bearing?
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What followed the loss of lube oil pressure?
What followed the loss of lube oil pressure?
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Crew's fire response included:
Crew's fire response included:
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Why shut down ventilation?
Why shut down ventilation?
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Suppression Method
Suppression Method
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Critical maintenance step?
Critical maintenance step?
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Tracking systems for parts?
Tracking systems for parts?
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Study Notes
- National Transportation Safety Board of the United States (NTSB) published "Safer Seas Digest 2023", which includes a number of incidents which may be of interest to IMCA members.
Incident Details
- An offshore supply vessel experienced a mechanical failure in its no. 3 main diesel generator engine, leading to an engine room fire during sea trials after maintenance.
- The fire was extinguished without injuries or pollution, but the vessel sustained approximately $1.1 million in damages.
Cause of the Incident
- A standard-sized connecting rod bearing on the no. 3 main engine did not meet specifications, leading technicians to replace all connecting rod bearings with standard-sized bearings.
- The no. 6 main bearing was unknowingly undersized with a smaller inner diameter but was not identified or recorded by the technician.
- Technicians replaced the no. 6 main bearing with a standard-sized bearing, expecting main bearing journals and connecting rod bearing journals to be machined simultaneously.
- The incorrectly sized no. 6 main bearing allowed lube oil leakage, reducing oil supply pressure to adjacent connecting rod journal bearings, leading to increased temperature and fractured bearing cap bolts.
- Several engine components broke free, causing hot oil and gas to start a fire in the engine room.
Crew's Response
- The crew responded effectively by stopping running engines, isolating fuel supplies, shutting down engine room ventilation, and closing air dampers and watertight doors.
- Tugboats returned to assist, and the crew activated the vessel's fixed CO2 fire extinguishing system.
Probable Cause Conclusion
- The mechanical failure and fire were likely caused by replacing a crankshaft main bearing with an incorrectly sized bearing during an engine overhaul.
- Engine service technicians failed to correctly identify the removed bearing's part number, leading to the loss of lube oil pressure in adjacent connecting rod bearings.
Lessons Learned
- Correct replacement of machinery components is critical for safe and reliable vessel operation during maintenance.
- Vessel crews and technicians should carefully identify and document part numbers of all removed components.
- Tracking systems should be used to ensure proper replacement part selection for reinstallation.
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