Corroded wire causes crew fatality
Lookout! Issue 26, September 2012
The men were carrying out routine scheduled maintenance on one of the passenger vessel’s 14 lifeboats. They were standing on the cabin roof about 16 metres above water level, greasing the lifeboat’s support cables, called fall wires. When the forward fall wire failed and the boat fell, the men’s safety harnesses, clipped to a line strung between the lifeboat’s lifting hooks, also snapped. The lifeboat remained suspended by its rear fall wire, but the men were thrown into the harbour.
Conditions were poor, with a stiff southerly breeze and choppy waters. The alarm was raised and the ship’s rescue boat was quickly launched. One of the men in the water grabbed a grease bucket and used it to stay afloat until he was rescued. He was treated for bruising and mild hypothermia and was able to return to work later that day.
The other man, who could not swim, was seen above water briefly but then disappeared. Despite the port authority, Coastguard and emergency services joining the search, it was four hours before divers located the second man’s body on the seabed near where he had gone into the water.
On examination, the fall wire was found to be severely corroded at the point where it had failed and had lost structural strength. The final failure had come when the remaining cross-section fractured under tension. Technical analysis found this section of wire had little grease compared with elsewhere on the wire.
The design of the hydraulic davits (lifting arms) for the vessel’s lifeboats was found to be flawed. The part of the wire that failed passed across the guides on the end of the fixed arm and was difficult to access for maintenance. It was hard to apply a protective coating of grease to it, and to make sure the circumference was completely coated. As a result, this part of the fall wire had not been properly inspected or lubricated during its four years in use. Salt water was able to penetrate and corrode its internal strands.
An examination of the vessel’s other davits identified 10 other badly corroded fall wires.
Vessel owners and the manufacturers of these and similar systems were alerted to the potential for this design flaw to compromise protective maintenance, causing corrosion and eventual failure of the fall wires.
- The fall wire broke because its internal strands had corroded to the point where it was too weak to support the weight of the lifeboat. In marine environments, which involve harsh saltwater conditions, wire ropes need regular and thorough inspection for signs of corrosion. The full length and circumference of the wire must be lubricated.
- The men’s safety harnesses did not support them because the line they were attached to failed when the fall wire failed. Consider where best to secure safety harnesses so that an unforeseen failure elsewhere need not affect the points where they are secured.
- The vessel had sound safety systems in place to prevent injuries or loss of life during maintenance procedures, but on this occasion they were not properly followed. No matter how carefully safety risks are identified and documented, accidents cannot be avoided unless crew follow the appropriate procedures.
- The men had on heavy clothing and workboots, but were not wearing lifejackets or buoyancy aids. Their clothing would have quickly become waterlogged and their boots filled with water, weighing them down. The man who died could not swim and was probably dazed by the impact of his fall from a height of 16 metres and the shock of entering cold water.
- However, had he been wearing a lifejacket, he is more likely to have been able to keep his head above water, increasing his chances of surviving until he could be rescued. Buoyancy aids such as lifejackets should always be worn when working outside a ship’s rail.