On July 5, 2020, about 0250 local time, the self-unloading bulk carrier Atlantic Huron was transiting the Upper St. Marys River, west of the Soo Locks, in Sault Sainte Marie, Michigan, with a crew of 25. While on approach to the locks and attempting to slow, there was a propulsion problem involving the vessel's controllable pitch propeller (CPP) system. The vessel subsequently contacted the west center pier at 6.8 knots. Before reaching the lock gate, the vessel's motion was halted, and the crew moored the vessel to the pier. No pollution or injuries were reported. Damages to the vessel ($1,633,000) and pier ($573,000) were estimated at $2.2 million.
The probable cause of the contact between the Atlantic Huron and the west center pier at Soo Locks was not following the manufacturer's requirement to use thread-locking fluid during installation of the feedback ring locking pin set screw on the vessel’' controllable pitch propeller system, which led to the failure of the controllable pitch propeller's oil distribution box.