Breakdown and Subsequent Drift of Bulk Carrier – Investigation Report

During a morning of May 2012, while transiting the Coral Sea, Bulk Carrier’s ID Integrity main engine shut down when its fuel pump reversing mechanism came free and jammed. This caused the camshaft to bend and slip in a drive coupling which resulted in the camshaft being out of timing and therefore the engine could not be restarted. The ship drifted in a westerly direction towards the Australian coast and the Great Barrier Reef. During the afternoon of the next day the ship passed over Shark Reef, located about 60 miles east of the Great Barrier Reef Marine Park. Luckily the incident ended without causing any damage to the environment or further damage to the ship’s systems, but the incident had the potential of evolving into a serious accident.

On 5 May 2012, the 185.74 m geared bulk carrier ID Integrity departed from Shanghai, China. The ship was in ballast and bound for Townsville, Australia, where it was to load a cargo of sugar. The ship travelled south through the western Pacific Ocean toward the northern coast of Papua New Guinea. During this time, the crew carried out an exchange of the ship’s ballast water in accordance with Australian ballast water management requirements. This process took about 3 days and required the running of two of the ship’s three diesel generators. While running two diesel generators, the ship’s engineers found that diesel generator numbers 2 (DG2) and 3 (DG3) could not carry the required load, so they dismantled and cleaned the turbochargers of both engines. The turbochargers were found heavily contaminated with carbon. In the days following this maintenance, DG2 was used to supply all the ship’s electrical needs.

Photo above: ID Integrity engine room layout

At about 0600 on 14 May (all times in this report are local time, UTC +10 hours), when the ship was in the Vitiaz Strait on the northern coast of Papua New Guinea (see figure below), DG2 shutdown without warning, the ship lost all electrical power (blacked out) and the main engine stopped. The engineers restored electrical power by starting diesel generator number DG1 and DG3 and the voyage was continued. Upon investigation, the engineers found DG2’s turbocharger rotor shaft had broken. Since there was no spare on board, the turbocharger could not be repaired and the generator was not run. The engineers left the remaining two diesel generators running in the belief that running two generators in parallel on low load provided more security of power supply than one generator running alone on higher load.

At 2200 on 15 May, ID Integrity passed through Jomard Passage (see figure below) and entered the Coral Sea. The weather was now from the southeast at Beaufort scale force 7 (28 to 33 knot winds with wave heights of 4 to 5.5 m). The master contacted the Australian Rescue Coordination Centre (RCC) and made an initial Australian Ship Reporting System (AUSREP) report.

Figure above: Section of navigational chart Aus4060 showing ID Integrity’s track, 14 to 22 May

At about 0930 on 16 May, in position 13° 16.5′ S 150° 46.3′ E, both diesel generators unexpectedly stopped when they were unable to carry the electrical load. The ship blacked out, the main engine stopped and the emergency generator automatically started, providing emergency power. Without propulsion, the ship turned beam on to the weather and swell, began to roll heavily and to drift in a westerly direction. DG3’s turbocharger was dismantled and cleaned and the engine put back into operation. DG1’s turbocharger was also dismantled, however, the engineers found the bearings had failed. Because there were no spares remaining on board, the turbocharger could not be repaired. In an effort to provide backup electrical power to support DG3, and as DG2’s turbocharger was already dismantled, the engineers decided to run DG2 normally aspirated. Aspirated refers to an engine operating without assisted air supply to the cylinders (by turbo-charging or super-charging). This reduces the density of air in the cylinders reducing the amount of fuel that can be burnt and therefore reducing the load carrying capacity of the engine.

At about 2000 on 16 May, the main engine was started, but it could not be run up to full speed because the number two cylinder air start valve was stuck open. The engine was shut down to repair the air start valve, but the engineers could not repair it in place and were unable to remove it from the engine as it was stuck fast in the cylinder head.

By the morning of 17 May, the air pipe leading to the faulty air start valve had been blanked off. The main engine was started, but this time its number six cylinder was not firing and the engine would not reach full speed. The main engine was shut down again and, after some consultation with the company’s shore-based technical superintendent, the engineers replaced the number six cylinder fuel valves (injectors) and the fuel pump delivery valve. During this time, the ship continued to drift in a westerly direction, rolling heavily in the rough seas.

At 1218 of 17 May, the master made an AUSREP deviation report (a report that is being made should a ship, at any time, be in a position more than 2 hours steaming from the position that would be predicted). He noted that the ship was stopped due to main engine problems and was drifting in a westerly direction at 3 knots. It was 150 miles from the nearest danger (Willis Islets to the south) and about 310 miles northeast of Cairns, Queensland. The master provided further information to the RCC as the day progressed.

At 0100 on 18 May, in position 13° 22.19′ S 148° 56.29′ E, the main engine was started and the voyage was resumed. The master reported to the RCC that the ship was making good a speed of 8 knots but had only one fully operational diesel generator.

At about 0550 on 18 May, in position 14°00.66′ S 148°30.87′ E, the main engine stopped again. No alarm sounded and the duty engineer could not identify a fault. The chief engineer was called and the engine room staff began searching for the cause of the shutdown. In the heavy seas, there had been repeated lubricating oil pressure alarms so attention was initially turned to verifying the integrity of the main engine lubrication system. No problems were found and several unsuccessful attempts were made to restart the main engine.

At 0859 on 18 May, the master reported to the RCC that the ship was drifting, with an expected stoppage time of about 3 hours. The RCC began to monitor ID Integrity’s progress. The ship was in no immediate danger (about 100 miles to the east of Osprey Reef) and the engineers continued to search for the cause of the main engine stoppage.

At 1815 on 18 May, the master contacted the RCC and reported that the ship was in position 14° 05’ S 148° 00’ E and that the main engine could not be started. The ship was drifting in a westerly direction at about 3 knots and would be closing on Shark Reef in about 20 hours. The Australian Maritime Safety Authority (AMSA) activated the Australian National Maritime Emergency Response Arrangements (NMERA) which included assessing the availability of towing resources. AMSA advised ID Integrity’s managers, of this action and the company began making arrangements to source other suitable towing vessels to assist.

On 19 May, two tugs were dispatched to assist ID Integrity. PT Kotor, a 23.5 m tug departed from Mourilyan (south of Cairns) and was expected to rendezvous with ID Integrity during the morning of 20 May. The 28.7 m tug PB Leichhardt departed from Townsville with an estimated arrival at the ship’s position during the evening of 20 May. ID Integrity’s engineers, in consultation with the managing company’s technical superintendent, continued to search for the cause of the main engine stoppage. While inspecting the engine, the engineers were slowly turning the engine using the turning gear (a reversible electric motor connected through a worm gear drive to the toothed flywheel of the main engine to allow slow turning of the engine) when the turning gear drive motor overloaded and tripped out. The chief engineer concluded that there was a physical obstruction in the engine that was causing an increased resistance to turning, so he decided to inspect the rotating components of the engine, starting with the camshaft. Upon removal of the camshaft cover from number six cylinder, he found pieces of the fuel pump cam, fuel pump roller and reversing mechanism (see figures below). Closer inspection showed damage to the cam and engine block surfaces (see figures below). The engineers cleaned the debris out of the camshaft space and began preparing to lift the number six fuel pump off the cam so they could attempt to run the main engine on the remaining five cylinders.

Photo above: Pieces removed from camshaft space

Photo above: Fuel pump cam and engine block damage

Photo above: Fuel pump cam damage

Photo above: Damage to roller guide housing

At 1305 on 19 May, the master reported to the RCC that the ship was rolling heavily in 2.5 to 3 m seas and 35 to 40 knot winds from the southeast. It was still drifting in a westerly direction at 3 knots and was about 14 miles from Shark Reef. As none of the tugs would reach the ship before it was likely to pass over Shark Reef, other contingencies, including the use of the ship’s anchors, were considered. It was agreed that the master would de-ballast the ship to reduce its aft draught to 5.0 m, increasing the ship’s under keel clearance to the maximum possible. The minimum charted depth for Shark Reef is 8.1 m.

At about 1830 on 19 May, ID Integrity drifted across the southern end of Shark Reef in waters about 20 m deep, about 4 miles south of the charted 8.1 m depth. ID Integrity was now about 60 miles from the eastern edge of the Great Barrier Reef Marine Park and was expected to close on it in less than 24 hours.

At 0900 on 20 May, the tug PT Kotor rendezvoused with ID Integrity and in the rough seas it took about an hour to connect a tow line. ID Integrity’s bow was then turned into the weather allowing it to ride more easily and its drift was arrested. The tug and tow moved in a south-easterly direction.

At 1715 on 20 May, the tug Pacific Responder arrived at ID Integrity’s position and, with darkness approaching, stood-by until the following morning. PB Leichhardt arrived later that evening.

During the morning of 21 May, Pacific Responder took over the tow and at 0815, with the other tugs as escorts, commenced towing ID Integrity toward Cairns.

At 0635 on 23 May, two pilots boarded the ship and guided the tow through the Grafton Passage and towards Cairns. By 1500, the ship was safely anchored off Cairns, and the tugs had been released. While ID Integrity was at anchor, the main engine and generators were repaired.

On 27 June, the ship sailed for Port Moresby, Papua New Guinea, where further repairs were carried out.

Safety issues contributing to the incident

• Over time, cracks had developed in the reversing link of the number six cylinder fuel pump. On 18 May 2012, the reversing link failed and the resulting debris jammed the fuel pump drive mechanism. As a consequence, a camshaft coupling slipped and the main engine could not be restarted.
• While the maintenance records on the ship suggested that the reversing mechanism and roller guides had been regularly inspected, there was no evidence to indicate what was checked, whether the reversing links had been crack tested or replaced, or if the cam follower guide block retaining screws and pins were ever inspected, retensioned or replaced.
• The ship’s planned maintenance system did not include all of the main engine manufacturer’s maintenance requirements.
• The maintenance records did not include sufficient detail to confirm that the main engine was maintained in accordance with the manufacturer’s requirements.
• The vessel’s Class did not have in place a system which ensured that updated service advice from the engine manufacturer was being implemented on board ships with engines which its surveyors were routinely and regularly surveying.
• In conducting repeated decarbonizing of the diesel generator turbochargers, the ship’s engineers had focussed on the symptoms rather than the causes of the turbocharger fouling. Over time, this approach had resulted in a reduction in the reliability of the machinery.

Recommendations

• The vessel’s managers were advised to take steps to inspect the roller guides in all main engines in their fleet as soon as practical or during dry dockings and carry out repairs as required. All Ship’s staff would be briefed and crew training centres include information regarding this incident. In addition, closer contact between on board and shore management would be instigated along with tighter restrictions on the use of shipboard computers and maintenance systems to limit the loss of information due to computer virus attacks.
• The vessel’s Class was advised that they were in discussion with MAN B&W about obtaining engine design and service information and that all relevant departments would share any design change information.
• The Class was also advised that survey reports are checked by head office and damage information arising from inspections, or from notices received from the equipment manufacturer, is analysed and recorded in the company survey database. This information is brought to the attention of, and made available to, class surveyors through a monthly damage list which is issued to all class surveyors. This information is also available to surveyors through company internal document systems.

Source: Australian Transport Safety Bureau (ATSB)