NTSB Posts Final Dali Findings

The National Transportation Safety Board (NTSB) has posted its final findings on the case of the mv. Dali, which struck and collapsed several spans of the Francis Scott Key Bridge in Baltimore Harbor on March 26, 2024. The allision and bridge collapse caused the deaths of six highway workers and shut down water-borne commerce to the port for months.

The report was preceded by an open meeting of the full NTSB board to hear the final results (WJ, November 21). The 259-page final report details the events—beginning with a single loose wire in a transformer block—that officials determined were the probable cause of the loss of electrical power that led the 213-million-pound container ship to crash into the bridge.

Having waited for the NTSB’s final report, HD Hyundai Heavy Industries (HHI) released an extensive statement following its own internal investigation that blamed the incident on shortcuts and neglect of inspection and maintenance by the operator. HHI built the vessel, and one key finding of the NTSB was that a single loose wire was the immediate cause of the cascading events that led to the strike. The NTSB made 24 safety recommendations to several entities in total.

“Floating City”

HHI pointed out that container ships like the mv. Dali are like “floating cities.” They have onboard power plants that power the ships’ systems for weeks at sea, thousands of miles from dock.

“When the mv. Dali was built and delivered to its initial buyer nearly a decade before the Key Bridge tragedy, it had a host of redundant systems with automatic restart capabilities. … These redundancies are so critical that they are required by the relevant classification society, an industry safety group,” HHI said.

The ship was delivered with two independent transformers to convert high-voltage electricity to low-voltage electricity to power certain equipment, including the fuel supply pumps and the main engine cooling system pump.

The two transformers, and their associated safety systems, also provide critical redundancy. If a transformer fails or its associated safety system detects an abnormal condition, the system is designed to switch to the other transformer to relieve the crew of having to troubleshoot the abnormal condition. Only one transformer is needed to provide low-voltage power to the ship at any given time.

“Some time after taking possession of the mv. Dali, the ship owner and operator circumvented the ship’s safeguards by compromising its critical redundancies,” HHI stated. “Instead of using the fuel supply pumps with automatic restart capabilities to provide fuel to two of the generators, they used a different type of pump—an electrical flushing pump. Unlike the fuel supply pumps, the flushing pump is used to clean out heavy fuel oil before it can solidify, clog the generator’s internal piping system and damage the generators. The flushing pump is also used during maintenance. Further, the flushing system lacks critical protections like temperature controls, viscosity monitors and certain filters. There is only one electrical flushing pump on the ship, and it is not designed to operate as a fuel supply pump to the generators. For these reasons, it can only be restarted manually. Using the flushing pump as a fuel supply pump sacrificed both redundancy and automation of the fuel supply system and violated established classification rules.

“On the day the mv. Dali hit the Key Bridge, the ship experienced two blackouts,” the HHI statement continued. “The first was reportedly caused by a wire disconnecting from a terminal block in the transformer #1 system. In response, because the transformer was being used in manual mode, the crew had to manually switch to transformer #2. However, when switching to transformer #2, the crew did not restart the flushing pump that had been supplying fuel to the operating generators, starving the generators of fuel and resulting in another blackout. Had the shipowner and operator used the ship’s transformer in automatic mode and the fuel supply system as designed and manufactured, power would have been restored within seconds, and the second blackout, which led to the tragedy, would not have happened.”

In other words, HHI contended that, even if a wire in a transformer system became loose over a decade, the redundant and automated systems would have immediately kicked on, switched to the other transformer, reestablished the fuel supply and provided the crew with ample opportunity to regain control of the ship without experiencing the second blackout.

HHI concluded, “The mv. Dali’s shipowner and operator used the vessel’s systems improperly and neglected their continuing inspection and maintenance obligations. They cut corners and violated class rules, which ultimately led to the tragic incident. Their failure to adhere to established safety standards compromised the vessel’s reliability, which led to the allision.

“HD Hyundai Heavy Industries joins the Baltimore community in mourning the tragic loss of life and extends its deepest condolences to the families,” HHI stated. “We will continue to work with the authorities to help prevent similar incidents from occurring in the future.”