NTSB reports on 2016 bulk carrier grounding

JANUARY 19, 2017 — The National Transportation Safety board says that the probable cause of November 2016 grounding of the 738 ft fully-laden bulk carrier Nenita in the Columbia River was the failure of a main engine cylinder cooling jacket that initiated an automatic reduction in engine speed, resulting in the eventual loss of steerage way.

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.

Water Chemistry

The NTSB Marine Accident Brief on the incident notes that 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 per the manufacturer’s recommended schedule, ensure levels of treatment are correct, and maintain water quality within specified limits. Insufficient cooling water maintenance may result in increased corrosion, clogging of cooling water passages, or, ultimately, the failure of equipment.

Tightening of Fasteners

Over the last two years, the NTSB has investigated three separate accidents that may have been caused by a failure to tighten fasteners on marine engines to the manufacturer’s recommended torque settings. Under-torqueing a fastener may cause excess vibration or allow the fastener to come loose, while over-torqueing 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 and torque values.

Read the NTSB Marine Accident Brief HERE