Ferry hit pontoons after mechanical failure, says report
Investigation finds fault occurred after engineer fitted a part without instructions.
A ferry that grounded lost control due to a mechanical failure after an engineer fitted a part without instructions, investigators have found.
The passenger ferry Hebrides crashed into mooring pontoons and grounded as it approached Lochmaddy on North Uist on September 25 last year with 77 people on board.
The Marine Accident Investigation Branch (MAIB) report found that the loss of control was caused by a mechanical failure within a linear servomotor actuator in the propulsion control system.
This failure resulted from a setscrew not being secured in position with thread locking compound when it was replaced six months earlier.
Marine investigators found that neither the service engineer who fitted the setscrew nor the ferry's engineers were aware of the manufacturer's service instructions on how to fit it, which had not been provided by Rolls-Royce Marine, the provider of the propulsion control system
Investigators said the lack of service instructions was "pivotal" to the failure.
They also found the crew's response to the loss of control was well intended but was "uncoordinated" because they were not sufficiently prepared or practised to deal quickly and effectively with the loss of pitch control in the confined waters.
None of the 32 crew or 45 passengers were injured in the incident, however the Caledonian MacBrayne ferry was damaged and had to be taken out of service and repaired in dry dock.
Investigators found that the service instructions for the actuator were not included in the system's engineering manuals provided by RR Marine that were carried on board Hebrides.
RR Marine had also not issued any information regarding the maintenance or inspection of the actuator.
The MAIB report said: "The absence of service instructions for the actuator's inspection and maintenance that were available from its manufacturer was pivotal to the failure."
It has issued a recommendation to Rolls-Royce Marine aimed at ensuring that service instructions are made available to service engineers and in documentation provided to vessels.
The MAIB has also recommended that CalMac Ferries Ltd ensure that recommendations for safety critical system upgrades received from manufacturers are properly documented and processed and that its crews are better prepared to deal effectively with propulsion failures.
CalMac has issued a technical bulletin to its major vessels that requires all propulsion controls, including emergency controls, at all stations are tested regularly and it has conducted its own investigation of the incident.
A spokesman said: "We note the MAIB's report which largely confirms the findings of our own investigation into the incident.
"Since the grounding in September last year we have put in place a number of processes to mitigate the issues raised and will continue to monitor these areas to ensure our procedures meet the highest possible standards and give our customers assurance that we take their safety very seriously."
Rolls-Royce Marine has issued a service letter to all users of the HeliconX propulsion control systems and a service procedure for the linear servomotor.
A Rolls-Royce spokesman said: "Rolls-Royce has noted the recommendations and will take these into consideration going forward."