BACKGROUND: On a dry, sunny, fall day in the Appalachians, a timber cutter was limbing his way up a large maple tree that he had just felled.
PERSONAL CHARACTERISTICS: The 49-year-old, experienced timber cutter was fully trained. He was wearing safety chain saw pants, hard hat with face screen, ear muffs, and cut-resistant boots.
UNSAFE ACT AND CONDITION: The chain saw bar’s roller tip sprocket rivets had either worn down or were damaged. Prior inspections failed to identify worn hardware.
ACCIDENT: As the cutter was limbing the tree, he suddenly felt the chain seize up and stop cutting. At the same time, he saw an object fly up toward his face, hitting his face screen. He first thought a piece of wood had chipped off the limb. However, he could see that the roller bar tip had spread open, allowing the sprocket to come out and puncture his screen.
The cutter turned off his saw and examined the roller tip. The rivets had broken loose, and the sprocket had cracked in half, allowing a portion of the sprocket to spin out of control towards his face screen. The screen had three puncture marks in the wire mesh, and the sprocket was lying in the leaves about five feet away.
INJURY: The cutter was not injured from this unexpected malfunction, but if he had neglected to use his screen, he would have suffered a serious face wound which might have prevented him from ever working in the woods again.
RECOMMENDATIONS FOR CORRECTION: Never ignore chain saw maintenance. Always inspect equipment before each use, and look for loose bolts, cracks, or other defects that might cause a mechanical failure. An improperly or poorly cared for chain saw may increase risk of injury. Review the chain saw’s instruction manual for recommended maintenance procedures, and to educate yourself on the risks of operating your equipment. Many manufacturers also offer helpful maintenance materials, including the proper maintenance of saw chain, drive sprockets, and guide bars. Always use all the required and recommended PPE (personal protective equipment) when operating a chain saw—protect yourself from the unexpected!
Courtesy of the Forest Resources Association: https://www.forestresources.org/