Dec 212010
 
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The passenger walkway collapsed

Britain’s Marine Accident Investigation Branch, MAIB, has urged the UK Major Ports Group, UKMPG, and British Ports Association, BPA, to review the risks of vessels running main engines while embarking or disembarking passengers and vehicles; and, inspect the passenger access structures in their ports, following the best practices and guidelines available on the subject from the civil engineering industry. The warning follows MAIB’s into unintended movement of the ro-ro passenger vessel Ben-My-Chree during loading operations at Heysham on 26 March 2010.

The accident was caused when the chief officer, intending to carry out pre-departure
control tests, set the pitch lever of both main propulsion engine CPPs to the 100%
ahead position. Expecting both shafts to be stationary, he had not noticed that the
starboard engine and shaft were running at sea speed with its CPP set on zero pitch.

The engineer who passed control of the engines to the bridge was not fully aware of  which machinery was running, and had not informed the chief officer that the starboard shaft was turning. Running the main engines in port during passenger and vehicle operations was a normal activity on board this vessel, carried out once every three days to facilitate water-washing of the turbochargers on the main engines.As all the mooring lines which could have restrained the vessel were set on autotension winches, the vessel surged forward as soon as the propeller thrust  overcame the preset tension on the winches.

Ben-My-Chree moved approximately 8m along the quayside, causing serious damage to the passenger access structure. The foot-passenger walkway detached at both ends and collapsed onto the quayside, and the gangway detached from the vessel’s side shell door and was left hanging on a single rope. Fortunately, there were no injuries. Eight passengers were trapped in the gangway compartment of the shore structure and were later rescued by the local fire service.

A number of weaknesses were evident in the passenger access structure, including:
• The quay on which the structure was built had suffered considerable settlement
over the years;
• The walkway was secured to the rest of the structure with only two small bolts
at either end, and;
• There were no records of inspections or maintenance work carried out on the
structure.

Ben-My-Chree had just completed an extended period of repairs in a dry dock but still had electrical faults on the main circuit breakers connecting the main engine driven  shaft generators to the bow thrusters. When Ben-My-Chree called at Heysham, shore
electricians rectified the faults, and in order to provide electrical power to test the bow thruster, the starboard main engine was started with its controllable pitch propeller (CPP) set to zero pitch.

In addition to the full accident report here MAIB has issued a safety flyer to the industry here.

MAIB warns:

1. Running main propulsion engines while a vessel is alongside is an extremely hazardous activity and must be controlled carefully. Several accidents in the past have resulted from failure of controllable pitch propeller (CPP) control systems resulting in propeller blades being inadvertently set to ahead or astern pitch. Sufficient safeguards must be put in place to mitigate the consequences if the CPP system fails to maintain the neutral position of the propeller blades and, specifically, to uncouple the hazards of engine operation from passenger or vehicle operations.

2. The use of autotension winches on ro-ro ferries significantly reduces the dependence on the crew to maintain the required tension in the mooring lines. However, opposing spring lines held on autotension winches can cause the vessel to ‘walk’ along the pier and may not restrain the vessel as well as mooring lines secured on bitts or held on winch brakes. Operators should conduct a detailed assessment to consider the balance of these risks and adapt their procedures accordingly.

3. Regular inspection and maintenance of facilities used by passengers is of paramount importance. Guidance is available for the design and construction of passenger access structures in the form of published reports and British Standards. In particular, the following are most relevant:

• Safety in Ports, Ship to Shore Linkspans and Walkways (CIRIA report C518)
• Maritime Structures: Code of Practice for the Design of Ro-Ro Ramps, Linkspans and Walkways (BS 6349-8:2007)
• Maritime Works: Code of Practice for the Design of Quay, Walls, Jetties and Dolphins (BS 6349-2: 2010).

4. It is crucial that crew members communicate openly and do not make assumptions about each others’ actions, especially when performing tasks which are not part of the daily routine.

The vessel owner, Isle of Man Steam Packet Company (IOM-SPC), has since implemented a policy allowing its vessels a minimum of 24 hours after finishing any extended maintenance period to test systems and rectify defects before resuming passenger service.

See also:

CFL Patron Contact: CPP Goes Wild – Expect It

Accident Report: CPP Gets Heat For Lock Bop

USCG warning on controllable pitch props

Queen of Nanaimo: Grounding: A Case of Loose Dowel Movements

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