Small screw came loose, big ferry grounded

Written by Nick Blenkey
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Hebrides aground

SEPTEMBER 15, 2017 — Loosening of setscrew less than 8 mm long led to the grounding of a 99 m long ROpax, according to the U.K. Marine Accident Investigation Branch report into the September 25, 2016 grounding of the Caledonian MacBrayne RO/RO passenger ferry Hebrides.

According to the MAIB report, the Hebrides was approaching Lochmaddy, North Uist, Scotland when control of the port controllable pitch propeller was lost.

The master attempted to control the ferry’s movements but he was unable to prevent it from running over several mooring pontoons and briefly grounding. There were no injuries but the ferry was damaged and had to be taken out of service and repaired in dry dock.

loosescrewThe loss of control was caused by the loosening of a setscrew (grub screw) within a servomotor assembly

Thread locking compound had not been used to secure the setscrew

Service instructions for the maintenance of the servomotor were not available to ship’s engineers or shore-based service engineers

An alarm system that had been recommended by the control system manufacturer had not been fitted

The bridge and engine control room teams were not sufficiently prepared or practiced to deal effectively with a loss of control in confined waters


Rolls-Royce Marine is recommended to verify its processes to ensure that service and inspection instructions provided by the original equipment manufacturers of the components used in its control systems are available to its service engineers and in the documentation provided to vessels.

CalMac Ferries Ltd (2017/137) is recommended to implement procedures that:

  • Document and process recommendations for safety critical system upgrades received from manufacturers.
  • Introduce drills and contingency plans to better prepare its crews to deal with propulsion failures.

Download the full report HERE

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