Rotor clearance issues or debris can lead to metallic contact sounds Loose or worn belts squeal or howl, especially under load Airflow pulsations, valve leaks, or turbulence create hissing or whistling Bolts, nuts, and mounting pads loosen over time, amplifying noise
[pdf] Abstract: At 1:30 p.m. on May 29, 2017, an employee was changing a seal on a power swivel. The rigging chain on the tong broke, striking the employee in the side of his head. The employee suffered a fractured skull and was killed. Keywords: Broken Chain, Fracture, Struck By
[pdf] 
