The National Transportation Safety Board (NTSB) has revealed that the Dali containership experienced a loss of electrical power before colliding with the Francis Scott Key Bridge in Baltimore, Maryland.
On 26 March, the Francis Scott Key Bridge collapsed after being hit by the Dali containership.
According to the NTSB, on 25 March, approximately 10 hours before departing Baltimore, the Dali had a blackout (loss of electrical power to the HV and LV buses) during in-port repairs.
While working on the diesel engine exhaust scrubber system for the diesel engine running the lone online generator no. 2, a crewmember accidentally closed an inline engine exhaust damper.
NTSB noted that closing this damper prevented the engine’s cylinder exhaust gases from travelling up the stack and out of the vessel, causing the engine to stall.
When the system identified a power outage, generator number three started automatically and connected to the HV bus.
READ: Port of Baltimore suspends traffic operations amid bridge collapse
The power was restored when crewmen manually closed the HR2 and LR2 breakers; however, low fuel pressure led its speed to drop, and its breaker (DGR3) opened, resulting in a second blackout.
During the recovery, the crew activated the TR1 transformer to power the low-voltage bus because the TR2 transformer had reportedly been in use for several months.
The HR1 and LR1 breakers suddenly opened, resulting in the first vessel blackout since departure on 26 March.
READ: Baltimore sues vessel owner and manager over bridge collapse
The NTSB is still examining the electrical arrangement following the initial in-port outage and its potential influence on the events of the voyage.
NTSB also revealed that there were no issues with the quality of the marine fuels used by the Dali containership. The ship reportedly utilised low-sulfur marine petrol oil (LSMGO), low-sulphur heavy fuel oil, and heavy fuel oil.
The collapse of the bridge resulted in six construction workers being killed.
