In this aerial view, a steel truss from the destroyed Francis Scott Key Bridge that was pinning the container ship Dali in place was detached from the ship using a controlled detonation of explosives in the Patapsco River on Monday in Baltimore, Md. Chip Somodevilla/Getty Images
WASHINGTON — The container ship that struck the Francis Scott Key Bridge had electrical problems the day before it left the Port of Baltimore when it was docked, according to a preliminary report released Tuesday by investigators at the National Transportation Safety Board.
The Dali experienced a "blackout" during maintenance about ten hours before leaving the port, the NTSB wrote in its report, when "a crewmember mistakenly closed an inline engine exhaust damper," causing the engine to stall.
The crew was able to restore power before the ship suffered a second blackout, investigators said. That prompted the crew to change the configuration of the ship's electrical system while still in port on March 25th.
But the NTSB says it's still not clear how those incidents relate to what happened early the following morning, when the Dali lost power twice in the minutes before it crashed into one of the bridge's supports.
"The NTSB is still investigating the electrical configuration following the first in-port blackout and potential impacts on the events during the accident voyage," the report says.
After the Dali lost power, authorities rushed to close the Key Bridge to traffic. Six construction workers were killed when the bridge collapsed into the Patapsco River, cutting off most maritime traffic into Baltimore's busy port and severing an interstate highway that carried 34,000 vehicles per day.
The effort to free the Dali took a major step forward this week with the controlled demolition of the largest remaining span of the collapsed bridge, which was resting on top of the ship's bow. Crews set off a chain of carefully placed explosives on Monday, letting off plumes of black smoke and a loud boom as the mangled steel trusses crashed into the water below.
Salvage crews continue to remove wreckage from the Dali six weeks after the cargo ship collided with the Francis Scott Key Bridge in Baltimore. Chip Somodevilla/Getty Images
The next step is to refloat the Dali so that it can be guided to a nearby terminal at the port for temporary repairs. The U.S. Army Corps of Engineers has opened a temporary alternate channel, and it is still working to restore a deeper channel for large container ships that typically use the port.
State and federal officials have pledged to rebuild the Key Bridge, but they acknowledge it won't be easy or quick. Meanwhile the legal fight over who will ultimately pay to replace the bridge is underway.
The NTSB and the FBI are separately investigating the incident. Their findings could play an important role in determining who is ultimately held liable for the accident.
From the NTSB's report, it appears that the harbor pilots who were in control of the vessel at the time of the accident were not aware of the ship's recent electrical problems.
"The senior pilot asked about the vessel's condition, and the captain reported that the ship was in good working order," according to the report.
Investigators at the NTSB say they analyzed samples of the fuel that was being burned at the time of the accident, as well as other fuel tanks on the vessel. But those results did not identify any concerns relating to the quality of the fuel, investigators said.
The NTSB says it's working with the Maryland Transportation Authority to assess its other bridges and to determine whether pier protection measures need to be improved. The MDTA is studying options for upgrades to the existing protection system around both spans of the Bay Bridge that connect Annapolis to the Eastern Shore of Maryland, according to the report.
"The NTSB investigation of all aspects of the accident is ongoing as we determine the probable cause," the report says.
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