BALTIMORE — The cargo ship Dali lost power twice before it hit the Francis Scott Key Bridge in March, and it suffered a pair of blackouts while docked hours earlier, according to the National Transportation Safety Board.
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The NTSB on Tuesday released a preliminary report on the crash , which sent the bridge into the Patapsco River, blocked access to the Port of Baltimore and claimed the lives of six construction workers.
Read More The Dali lost power around 1:25 a.m. on March 26 as it was about three ships’ lengths from the Key Bridge. Two electrical breakers unexpectedly tripped, taking out the lights and causing pumps required for the engine to keep operating to stop working, according to the report.
[ Francis Scott Key Bridge collapse: Crews conduct controlled demolition of span ]
The main engine shut down automatically, and the ship lost propulsion. Crewmembers were able to get power back, but they lost it again when another set of breakers tripped as the ship was .2 miles from the bridge.
Authorities were able to close the bridge to traffic about one minute before the Dali struck it. The collision threw members of a crew working to fix potholes on the bridge into the water, killing six. One person on the Dali was injured while escaping debris, officials said.
[ Francis Scott Key Bridge collapse: Workers recover sixth body from site ]
About an hour and a half before the crash, the ship’s captain had reported that the Dali “was in good working order,” according to the NTSB. However, the agency noted that the ship also lost power twice about 10 hours before it left port.
On March 25, the ship experienced a blackout during in-port maintenance, the NTSB said. A crewmember working on a system for the ship’s diesel engine “mistakenly closed an inline engine exhaust damper,” according to investigators.
“Closure of this damper effectively blocked the engine’s cylinder exhaust gases from traveling up its stack and out of the vessel, causing the engine to stall,” the NTSB said in its preliminary report.
[ Key Bridge: 1st container ship reaches Port of Baltimore since bridge collapse ]
Power was restored, but it was lost once more due to “insufficient fuel pressure for the online generator,” officials said.
It was not immediately clear how the outage on March 25 might have impacted the later crash.
“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 agency said in its report.
Authorities continue to investigate.
Bridge collapse Parts of the Francis Scott Key Bridge remain after a container ship collided with a support Tuesday, March 26, 2024, in Baltimore. The major bridge in Baltimore snapped and collapsed after a container ship rammed into it early Tuesday, and several vehicles fell into the river below. Rescuers were searching for multiple people in the water. (AP Photo/Steve Ruark) (Steve Ruark/AP)
Bridge collapse Parts of the Francis Scott Key Bridge remain after a container ship collided with a support Tuesday, March 26, 2024 in Baltimore. The major bridge in Baltimore snapped and collapsed after a container ship rammed into it early Tuesday, and several vehicles fell into the river below. Rescuers were searching for multiple people in the water. (AP Photo/Steve Ruark) (Steve Ruark/AP)
Bridge collapse The Dali container vessel after striking the Francis Scott Key Bridge that collapsed into the Patapsco River in Baltimore, Maryland, US, on Tuesday, March 26, 2024. The commuter bridge collapsed after being rammed by the Dali ship, causing vehicles to plunge into the water. Photographer: Al Drago/Bloomberg via Getty Images (Bloomberg/Bloomberg via Getty Images)
Bridge collapse The steel frame of the Francis Scott Key Bridge sit on the water after it collapsed in Baltimore, Maryland, on March 26, 2024. The bridge collapsed after being struck by a container ship, sending multiple vehicles and up to 20 people plunging into the harbor below. "Unfortunately, we understand that there were up to 20 individuals who may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN. Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge. (Photo by Jim WATSON / AFP) (Photo by JIM WATSON/AFP via Getty Images) (JIM WATSON/AFP via Getty Images)
Bridge collapse The Dali container vessel after striking the Francis Scott Key Bridge that collapsed into the Patapsco River in Baltimore, Maryland, US, on Tuesday, March 26, 2024. The commuter bridge collapsed after being rammed by the Dali ship, causing vehicles to plunge into the water. Photographer: Al Drago/Bloomberg via Getty Images (Bloomberg/Bloomberg via Getty Images)
Bridge collapse The Dali container vessel after striking the Francis Scott Key Bridge that collapsed into the Patapsco River in Baltimore, Maryland, US, on Tuesday, March 26, 2024. The commuter bridge collapsed after being rammed by the Dali ship, causing vehicles to plunge into the water. Photographer: Al Drago/Bloomberg via Getty Images (Bloomberg/Bloomberg via Getty Images)
Bridge collapse The Dali container vessel after striking the Francis Scott Key Bridge that collapsed into the Patapsco River in Baltimore, Maryland, US, on Tuesday, March 26, 2024. The commuter bridge collapsed after being rammed by the Dali ship, causing vehicles to plunge into the water. Photographer: Al Drago/Bloomberg via Getty Images (Bloomberg/Bloomberg via Getty Images)
Bridge collapse The collapsed steel frame of the Francis Scott Key Bridge and a section of the roadway still upright (L) sit on the water after the bridge collapsed in Baltimore, Maryland, on March 26, 2024. The bridge collapsed after being struck by a container ship, sending multiple vehicles and up to 20 people plunging into the harbor below. "Unfortunately, we understand that there were up to 20 individuals who may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN. Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge. (Photo by Jim WATSON / AFP) (Photo by JIM WATSON/AFP via Getty Images) (JIM WATSON/AFP via Getty Images)
Bridge collapse The steel frame of the Francis Scott Key Bridge sit on the water after it collapsed in Baltimore, Maryland, on March 26, 2024. The bridge collapsed after being struck by a container ship, sending multiple vehicles and up to 20 people plunging into the harbor below. "Unfortunately, we understand that there were up to 20 individuals who may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN. Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge. (Photo by Jim WATSON / AFP) (Photo by JIM WATSON/AFP via Getty Images) (JIM WATSON/AFP via Getty Images)
Bridge collapse The steel frame of the Francis Scott Key Bridge sits on top of a container ship after it struck the bridge in Baltimore, Maryland, on March 26, 2024. The collapsed sent multiple vehicles and up to 20 people plunging into the harbor below. "Unfortunately, we understand that there were up to 20 individuals who may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN. Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge. (Photo by ROBERTO SCHMIDT / AFP) (Photo by ROBERTO SCHMIDT/AFP via Getty Images) (ROBERTO SCHMIDT/AFP via Getty Images)
Bridge collapse The steel frame of the Francis Scott Key Bridge sits on top of a container ship after it struck the bridge in Baltimore, Maryland, on March 26, 2024. The collapsed sent multiple vehicles and up to 20 people plunging into the harbor below. "Unfortunately, we understand that there were up to 20 individuals who may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN. Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge. (Photo by ROBERTO SCHMIDT / AFP) (Photo by ROBERTO SCHMIDT/AFP via Getty Images) (ROBERTO SCHMIDT/AFP via Getty Images)
Bridge collapse Baltimore Fire Department Chief James Wallace, with Police Commissioner Richard Worley (R) and Mayor Brandon Scott (2nd R), speaks at a press conference on the collapse of the Francis Scott Key Bridge Baltimore, Maryland, on March 26, 2024. The bridge collapsed early March 26 after being struck by a container ship, sending multiple vehicles and up to 20 people plunging into the harbor below. "Unfortunately, we understand that there were up to 20 individuals who may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN. Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge. (Photo by Jim WATSON / AFP) (Photo by JIM WATSON/AFP via Getty Images) (JIM WATSON/AFP via Getty Images)
Bridge collapse A section of the roadway still stands after the collapse of the Francis Scott Key Bridge after it was struck by a container ship, in Baltimore, Maryland, on March 26, 2024. The collapsed sent multiple vehicles and up to 20 people plunging into the harbor below. "Unfortunately, we understand that there were up to 20 individuals who may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN. Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge. (Photo by Mandel NGAN / AFP) (Photo by MANDEL NGAN/AFP via Getty Images) (MANDEL NGAN/AFP via Getty Images)
Bridge collapse A US Coast Guard helicopter flies over the Dali container vessel after it struck the Francis Scott Key Bridge that collapsed into the Patapsco River in Baltimore, Maryland, US, on Tuesday, March 26, 2024. The commuter bridge collapsed after being rammed by the Dali ship, causing vehicles to plunge into the water. Photographer: Al Drago/Bloomberg via Getty Images (Bloomberg/Bloomberg via Getty Images)
Bridge collapse TOPSHOT - The steel frame of the Francis Scott Key Bridge sits on top of a container ship after it struck the bridge in Baltimore, Maryland, on March 26, 2024. The collapsed sent multiple vehicles and up to 20 people plunging into the harbor below. "Unfortunately, we understand that there were up to 20 individuals who may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN. Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge. (Photo by ROBERTO SCHMIDT / AFP) (Photo by ROBERTO SCHMIDT/AFP via Getty Images) (ROBERTO SCHMIDT/AFP via Getty Images)
Bridge collapse The Dali container vessel after striking the Francis Scott Key Bridge that collapsed into the Patapsco River in Baltimore, Maryland, US, on Tuesday, March 26, 2024. The commuter bridge collapsed after being rammed by the Dali ship, causing vehicles to plunge into the water. Photographer: Al Drago/Bloomberg via Getty Images (Bloomberg/Bloomberg via Getty Images)
Bridge collapse The steel frame of the Francis Scott Key Bridge sits on top of a container ship after it struck the bridge in Baltimore, Maryland, on March 26, 2024. The collapsed sent multiple vehicles and up to 20 people plunging into the harbor below. "Unfortunately, we understand that there were up to 20 individuals who may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN. Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge. (Photo by Mandel NGAN / AFP) (Photo by MANDEL NGAN/AFP via Getty Images) (MANDEL NGAN/AFP via Getty Images)
Bridge collapse The steel frame of the Francis Scott Key Bridge sits on top of a container ship after it struck the bridge in Baltimore, Maryland, on March 26, 2024. The collapsed sent multiple vehicles and up to 20 people plunging into the harbor below. "Unfortunately, we understand that there were up to 20 individuals who may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN. Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge. (Photo by ROBERTO SCHMIDT / AFP) (Photo by ROBERTO SCHMIDT/AFP via Getty Images) (ROBERTO SCHMIDT/AFP via Getty Images)
Bridge collapse The steel frame of the Francis Scott Key Bridge sits on top of a container ship after it struck the bridge in Baltimore, Maryland, on March 26, 2024. (Jim Watson/AFP via Getty Images)
Key Bridge in Baltimore collapses (Anadolu/Anadolu via Getty Images)
Bridge collapse The steel frame of the Francis Scott Key Bridge sits on top of a container ship after it struck the bridge in Baltimore, Maryland, on March 26, 2024. (Jim Watson/AFP via Getty Images)
Demolition begins: Crews conduct a controlled demolition of a section of the Francis Scott Key Bridge resting on the Dali container ship in Baltimore. (Roberto Schmidt/AFP via Getty Images)
Demolition: The Dali container vessel and the Francis Scott Key Bridge that collapsed into the Patapsco River during a controlled demolition in Baltimore. (Bloomberg/Bloomberg via Getty Images)
Demolition: The Army Corps of Engineers sets off a controlled demolition to remove wreckage from the Francis Scott Key Bridge off of the cargo ship Dali. (Kevin Dietsch/Getty Images)
Demolition: The Army Corps of Engineers sets off a controlled demolition to remove wreckage from the Francis Scott Key Bridge. (Kevin Dietsch/Getty Images)
Demolition: A controlled demolition to remove wreckage from the Francis Scott Key Bridge off of the cargo ship Dali was conducted in the Patapsco River. (Kevin Dietsch/Getty Images)
Demolition: The Army Corps of Engineers sets off a controlled demolition to remove wreckage from the Francis Scott Key Bridge off of the cargo ship Dali. (Kevin Dietsch/Getty Images)
Demolition: The Dali container vessel and the Francis Scott Key Bridge that collapsed into the Patapsco River during a controlled demolition in Baltimore. (Bloomberg/Bloomberg via Getty Images)
Demolition: Crews conduct a controlled demolition of a section of the Francis Scott Key Bridge resting on the Dali container ship in Baltimore. (ROBERTO SCHMIDT/AFP via Getty Images)
Demolition: Crews conduct a controlled demolition of a section of the Francis Scott Key Bridge resting on the Dali container ship. (ROBERTO SCHMIDT/AFP via Getty Images)
Demolition: A planned explosion cuts apart a section of steel truss from the Francis Scott Key Bridge that was draped across the bow of the Dali. (Baltimore Sun/TNS)