A new report from the National Transportation Safety Board (NTSB) suggests that a loose wire aboard the container ship Dali may have caused the blackout that led to the ship crashing into the Francis Scott Key Bridge on March 26.
According to the report, HD Hyundai Heavy Industries (HHI) engineers discovered that a loose cable connection at node 381 in the control line led to the accident. This loose connection could cause a power interruption to the HR1 UVT coil, resulting in an undervoltage trip and a blackout of the 440V switchboard.
When HHI simulated the disconnection of the cable, the HR1 relay opened, causing a blackout of equipment powered by the switchboard. The power was restored after 10 seconds through an automatic transfer, confirming the issue. The results aligned with the engineers’ expectations, leading to extended monitoring.
To remind, according to the NTSB preliminary report, electrical breakers HR1 and LR1 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.
Regarding the cause of why the breakers DGR3 and DGR4 tripped (opened), leading to the second blackout as reported in the previous NTSB report, do the NTSB and Hyundai have any findings on this?