Maintenance error led to $3.8 million marine casualty in Washington

March 15, 2022

On April 22, 2021, whilst the vessel was conducting a article-servicing sea trial in Puget Sound, the no. 3 principal motor seasoned a connecting rod assembly failure and ejected factors that breached the crankcase. Washington State Division of Transportation photo

An improperly tightened fastener led to a diesel motor failure on the passenger and vehicle ferry Wenatchee around Bainbridge Island, Clean., resulting in approximately $3.8 million in damages, the Countrywide Transportation Protection Board explained Tuesday.

Maritime Investigations report 22/06 details the NTSB’s investigation into the April 22, 2021, catastrophic failure of the no. 3 key motor aboard the Wenatchee for the duration of a sea trial in Puget Sound. The failure led to the ejection of elements from the motor and resulted in a fireplace in the no. 2 engine space. No injuries or air pollution were noted.

In November 2020, the Wenatchee, operated by Washington Condition Ferries (WSF), was taken out of service for upkeep. Throughout the upkeep period, two of the four main diesel engines, quantities 2 and 3, had been overhauled by factory-skilled technicians. In February 2021, pursuing the completion of engine overhauls, the vessel crew conducted motor assessments. Alarms activated for the no. 3 main motor. Crew customers located parts of a cigarette lighter in the lube oil method. Experts returned to examine the motor and get better the parts they recommended WSF it was satisfactory to run the engine.

On April 22, when the vessel was conducting a submit-servicing sea demo in Puget Audio, the no. 3 key motor expert a connecting rod assembly failure and ejected factors that breached the crankcase, ensuing in the ignition of sizzling pressurized gases that ended up released in the engine home. The crew of the Wenatchee correctly contained the unfold of the hearth by stopping all gas source and air flow to the engine room and isolating the space.

The NTSB determined the possible lead to of the mechanical failure of the no. 3 main motor was a connecting rod assembly that arrived unfastened and separated from the crankshaft due to insufficient tightening (torqueing) of a reduce basket bolt through the earlier engine overhaul.

“When installing fasteners, personnel need to use a calibrated torque wrench, follow the manufacturer’s proposed tightening tutorial and torque values, and validate that all expected torque requirements have been done,” the report claimed. “Undertorqueing a fastener might cause excess vibration or make it possible for the fastener to appear free, when overtorqueing may possibly direct to failure of the fastener or the machinery element remaining secured.”

The NTSB has earlier investigated other causalities triggered by improperly torqued fasteners, like an motor area fire aboard the cruise ship Carnival Liberty in 2015, a hearth aboard bulk provider Nenita in 2016 and an engine failure on the offshore offer vessel Pink Dawn.