BALTIMORE -- The shipping vessel that crashed into the Francis Scott Key Bridge in March experienced two power blackouts while docked, 10 hours before the collision that toppled part of a bridge span, according to a preliminary report released Tuesday by the National Transportation Safety Board (NTSB).
In addition to two power losses while the ship was in port, there were two power failures in the moments leading up to the crash, causing the ship's main to shut down, according to the NTSB. The crew was unable to regain propulsion before it slammed into the bridge, the report said.
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Federal investigators say fuel tests did not show irregularities and they are now focusing the probe on the ship's electrical system.
The M/V Dali experienced two blackouts on March 25 while the Sri Lankan-based ship was undergoing maintenance at the Seagirt Marine Terminal in Baltimore Harbor, the report said.
A crew member mistakenly closed an inline engine exhaust damper for one of the vessel's four diesel generators, which blocked the engine's exhaust gases from exiting the vessel, according to the NTSB. That, in turn, caused the engine to stall and diesel generators to stop working, the report said.
When the Dali's systems detected the power loss, another generator started, according to the NTSB report.
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Crews were able to get the first generator back online. However, a second blackout occurred when "insufficient fuel pressure caused [the second generator's] speed to decrease, and its breaker ... opened," causing another blackout, according to the NTSB.
After crews were able to re-open the exhaust damper for the first malfunctioning generator, it automatically restarted and power was restored, the report said.
The Dali slammed into the Francis Scott Key Bridge over Baltimore Harbor at 1:28 a.m. ET on March 26, causing part of a bridge span to collapse during the early morning hours of March 26 after it experienced two blackouts. The first blackout caused the Dali's engine to shut down and its propeller stopped, according to the report.
The report found that the Dali lost power twice the night of the incident as it made its way out of port.
The first power loss shut down the main engine, according to the NTSB. The crew was able to restore power, but then the ship lost power again moments later when it was approaching the bridge, according to the NTSB.
The crew was able to regain power again but unable to regain propulsion, the report said.
"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 said.
There were no reported blackout incidents recorded when the Dali was docked at ports in Newark and Norfolk during its recent U.S. voyage, according to the NTSB.
Video of the incident showed the lights on the Dali going off and smoking coming from the ship before it crashed.
Crews onboard were able to warn officials about the malfunction, giving them time to close off the bridge to oncoming traffic before the crash. However, six men, who were working on the bridge, were not able to get off and were killed.
The crash affected entry into the Port of Baltimore for weeks as the debris blocked entry for other ships.
The investigation and recovery efforts are ongoing. The final NTSB report with the cause of the incident could take up to two years to complete.
The Dali has remained stuck at the crash site but recovery teams made progress this week after they set off controlled explosions Monday to remove the section of the bridge that was attached to the boat.