Cracked cooling jacket on main engine no. 3 cylinder, postaccident. Arrow shows one of four hex head securing bolts for the jacket cover. (Photo by Coast Guard)
The National Transportation Safety Board (NTSB) issued an investigation report on the Grounding of Bulk ‘Carrier Nenita’ on the Columbia River, in November 2016, as a result of an engine failure combined with inefficient communication onboard.
On November 19, 2016, the fully-laden bulk carrier Nenita, registered in the Marshall Islands, was outbound on the Columbia River when the vessel suffered an engine failure impacting its ability to maneuver.
Damage to Nenita’s bulbous bow starboard side. (Photo by Spring Marine Bulk, S.A.)
The vessel subsequently ran aground at Three Tree Point on the Washington State side of the river, damaging its bulbous bow and hull. After the grounding, the Nenita was towed to Longview, Washington, for temporary repairs. Two weeks later, the vessel resumed the voyage to its original destination. There were no injuries or reported pollution as a result of the accident.
The National Transportation Safety Board determines the probable cause of the grounding of the bulk carrier Nenita was the failure of a main engine cylinder cooling jacket that initiated an automatic reduction in the engine speed, resulting in the eventual loss of steerageway. Contributing to the accident was the lack of information relayed from shipboard personnel to the pilot about the status of the main engine, which prevented him from taking effective corrective action following the engine casualty.
As a result of this report, the National Transportation Safety Board makes the following safety recommendations:
Comparison of bolts removed from no. 3 cylinder cooling jacket and replacement bolts shows same diameter and thread length, but unthreaded shoulder length of the replacement bolt was 2 millimeters longer. Also note damaged threads on leftmost bolt in right photo
- Water Chemistry: Maintaining proper water chemistry in engine cooling water systems reduces corrosion, scale, and the formation of deposits, which ensures effective cooling (heat transfer) to satisfy the system’s operating requirements. Mariners should conduct testing as per the manufacturer’s recommended schedule, ensure that the levels of treatment are correct, and maintain the water quality within specified limits. Insufficient cooling water maintenance may result in increased corrosion, clogging of cooling water passages, resulting in equipment failure.
- Tightening of Fasteners: Over the last two years, the NTSB has investigated three separate accidents that ,might have been caused by failure to tighten fasteners on marine engines as per the manufacturer’s recommended torque settings. Undertorquing a fastener may cause excess vibration or allow the fastener to fall apart, while overtorquing may lead to failure of the fastener or the machinery component being secured. When installing fasteners, mariners should use a calibrated torque wrench and follow the manufacturer’s recommended tightening guide to apply torque values.
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