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Summary

Summary

On 19th April 1994 the New Zealand flag ro-ro vessel Union Rotoma was on passage from Nelson in New Zealand to Port Botany in NSW when, at 1835, alarms were sounded by the vessel's automatic fire detection system indicating a fire in the engine room. The duty engineer quickly reported that the aft end of the port main engine was on fire. The fire was spreading very rapidly and the decision was taken to evacuate the engine room and to flood it with the ship's fixed carbon dioxide extinguishing system. A "Mayday" message was transmitted by Inmarsat C and was acknowledged by the Maritime Rescue Coordination Centre in Canberra.

While the crew were shutting down the engine room, the bulk CO was released. The main engines had been stopped from the bridge. Shortly after the release, the running generator stopped, indicating that it had been stifled by the CO. Approximately one and a half hours after the release of CO, two engineers wearing breathing apparatus made an inspection of the engine room and reported that the fire had been extinguished and there were no remaining hot spots.

The engine room was purged of CO before a further inspection was made and the generators were started to restore full electrical power. The inspection revealed that oil, spraying from a fractured pipe on the starboard engine, had ignited on the hot exhaust manifolds of the port engine. The pipe, carrying lubricating oil to the engine's overspeed trip mechanism and to the camshaft bearings, had been fractured by the movement of the camshaft anchor bearing housing moving out of the entablature, into which it had been secured by eight 20mm diameter set bolts, all of which had sheared or worked loose.

Damage caused by the fire was slight, involving mainly instrumentation and wiring. The ship was able to proceed on its voyage to Port Botany using only the port main engine.

The incident was investigated by the Marine Incident Investigation Unit under the provisions of the Navigation (Marine Casualty) Regulations.

Conclusions

These conclusions identify the different factors contributing to the accident and should not be read as apportioning blame or liability to any particular organisation or individual.

  1. The fire in the engine room was caused by a spray of lubricating oil, from a fractured pipe on the starboard main engine, being ignited by the hot exhaust manifolds on the port engine.
  2. The lubricating oil pipe was fractured when the housing for the camshaft anchor bearing worked its way out of the entablature, consequent upon the failure of the eight securing set bolts.
  3. The set bolts which secured the bearing housing in the entablature had no form of locking and should have had cross-drilled heads and been laced with locking wire.
  4. It was not possible to ascertain when the securing set bolts had been fitted, but it appears that they must have been fitted when the vessel was in the hands of previous owners. At the time that they were fitted, they were probably not pre-loaded to the required torque.
  5. Engine vibration would have contributed to the failure of the bolts.
  6. The response of the vessel's firefighting organisation was both fast and effective. This was due in large part to the fact that all officers and key personnel had personal UHF radios and excellent communications were maintained between all those involved throughout the incident.
  7. Realistic fire drills carried out on a regular basis, incorporating such techniques as using radios while wearing breathing apparatus and scenarios such as engine room fires requiring C02 flooding, contributed to the efficiency with which the fire was extinguished.
  8. No portable oxygen analysers were available on board with which to test the atmosphere in the engine room after it had been vented to clear the CO. Although not a statutory requirement, had one of these been available it would have minimised the risk to personnel when re-entering a space which had been flooded with CO.
 
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