Improper Brake Pad Disengagement Causes Anchor Drag

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Summary of the Incident

Less than three weeks before a barge’s 12,000-pound anchor was dragged across Line 5, the barge and its newly installed anchor brake system were inspected by the U.S. Coast Guard and the American Bureau of Shipping and found the system to be satisfactory. 

Six days later, when the American Bureau for Shipping performed its own inspection, the inspector was not told of the new brake pad but performed a functional test of the anchor and found the system was satisfactory. 

Sometime after the inspections, two crew members tasked with bow watch on the Erie Trader saw that the starboard anchor was protruding 1 to 2 feet from the barge. They assumed the brake system repairs still had not been completed, according to the report. 

But on April 1, 2018, the improper installment of the anchor brake pad, the unexplained disengagement of two backup brakes, a series of communication errors, and icy, rough waters caused the starboard anchor to pay out over the Straits of Mackinac, where it was dragged over a dual oil pipeline and severed three transmission cables, according to a U.S. Coast Guard report. 

The Coast Guard boarded the Erie Trader near the Soo Locks on April 6 and immediately saw the missing flukes on the starboard anchor. No drug or alcohol testing was performed on crew members because it was five days after the incident. 

During a follow-up inspection on May 7 in Oregon, Ohio, the Coast Guard found a “noticeable gap” between the brake drum and liner and friction spots and areas where paint “was burned away.”

Probable causes

  • The dielectric fluid spill was considered “minor” by the Coast Guard. Neither PCBs nor benzene compounds were found in the fluid, and no sheen was ever observed on the water’s surface.
  • It’s possible, Hjerstedt said, that during the Coast Guard inspection the brake pad misalignment discovered after the incident “may not have been readily apparent at the time of inspection.”
  • In March 2018, the 740-foot Erie Trader barge had repairs performed to its propeller system and a brake band on the starboard anchor that had cracked in 2017. But the installation was performed with no specific instructions for replacement of the band.
  • The Coast Guard was unable to determine who disengaged the paw and claw, but noted “it would have been impossible for these devices to become disengaged on their own.”
  • The Coast Guard believes headwinds closer to the Straits likely jostled the iced anchor. The weight of the chain and anchor on the improperly installed brake would have grown exponentially and pulled the anchor down farther.

Actions Taken

  • In the Coast Guard report, the investigating officer recommended the suspension and revocation of the mariner credentials of a crew member onboard the Erie Trader barge and Clyde S. Vanenkevort tug. 
  • Six months after the incident, the Coast Guard established a Regulated Navigation Area in the Straits of Mackinac prohibiting ships from anchoring within a mile of any charted cables or pipelines.
  • The Coast Guard recommended disciplinary action for both crew members.

Conclusion

  • The report from the Coast Guard follows a June 2019 report from the National Transportation Safety Board, which concluded a combination of human error and mechanical failure likely led to the anchor drop incident. 
  • The Coast Guard report came to similar conclusions but went into more detail regarding the faulty anchor brake system and oversights by crew members.

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Source: The Detroit News

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