NTSB releases new update on Dali investigation

Written by Nick Blenkey
Dali investigation

Photo: NTSB

As the Dali, the ship that struck the Francis Scott Key Bridge, was finally leaving Baltimore yesterday, the National Transportation Safety Board published an update on its ongoing investigation. It cautions that the Dali investigation update “does not contain analysis and does not discuss probable cause in this ongoing investigation. As such, no conclusions regarding the cause of the contact should be made based on the information contained in the update. The information in the update is preliminary and subject to change as the investigation continues.”

The update says that NTSB investigators have completed in-person interviews of the vessel’s crew. Onboard examination of engineering systems and testing of electrical systems has been completed. Documentation of the damage to the vessel structure is ongoing.

In its preliminary report (see earlier story), the NTSB said the Dali had experienced two electrical blackouts on the accident voyage and had suffered two while in port the previous day.

The Dali investigation update says that, during the accident voyage, electrical breakers HR1 and LR1 [in the ship’s electrical power distribution system] unexpectedly opened when the vessel was three ship lengths from the Francis Scott Key Bridge, causing the first blackout to all shipboard lighting and most equipment. While examining and testing the vessel’s electrical power distribution system and control circuitry, NTSB investigators noted an interruption in the control circuit for HR1’s undervoltage release (a device that opens a breaker when voltage falls below predetermined thresholds).

Dali investigation image
Exemplar terminal block identical to model removed from ship. (Source: WAGO)

NTSB investigators subsequently removed an electrical component, a terminal block,(an insulated block that connects two or more wires together).​​ from the control circuit for HR1’s undervoltage release. Two portions of control wiring associated with the terminal block were also removed.

“We continue to examine the removed components at the NTSB Materials Laboratory,” says the update. “We will continue to evaluate the design and operation of the vessel’s electrical power distribution system, and investigate all aspects of the accident to determine the probable cause and identify potential safety recommendations.”

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