Abstract: At approximately 9:48 a.m. on April 6, 2017, Employee #1 was repairing the cutting edge on bottom of Fisher EZ-V snowplow. The cutting edge on the plow was bent. He supported the right side of the plow on a 7-ton jack stands and used a C clamp to straighten the bent cutting edge. When the C clamp would not work, he used the arm of a Komatsu PC78 MR excavator to bend the cutting edge back and hold it in position. Lying on a mechanic's creeper, he slid under the plow and attempted to attach the V-plow flap mounting weldment bracket, which attached to the bottom of the plow with two bolts. While working under the plow, Employee #1 struck the mounting bolts with a 3-pound sledgehammer to align them. The vibration from the hammer caused the excavator bucket to slip and the bucket struck him in his head, causing skull fracture. Employee #1 was transported to a medical center, where he received treatment and was then hospitalized.