Summary
A grapple skidder was across the hill on a 40% slope. It became unstable on a narrow bench of land that was the upper portion of the cable yarding area. The skidder rolled over twice on the bench land and then it continued to roll many more times down much steeper terrain. The seat belt had previously been damaged and it tore in half during the incident. The skidder operator sustained fatal injuries.

Conclusions

Findings as to causes

• The skidder lost stability on a 40% slope. The sudden destabilizing event resulted in a rapid shift of weight distribution and quickly changed the skidder's centre of gravity and surface traction. Once the machine became unstable, the skidder operator could not restore the skidder's stability or stop the multiple-rollover incident from continuing.

• Operating the skidder across the slope created an increased potential for machine instability.
• The skidder was working on a 40% slope at the time of the rollover. There were no written safe work procedures regarding rubber-tired skidders operating on slopes greater than 35%.
• The skidder was working in close proximity to very steep terrain as it was on a bench next to a steep hill with a 65-79% slope. Although this was not a factor in the initial loss of stability causing the rollover, the steep hill contributed to the continuation of the rollover and the severity of the incident.
• The seat belt failed during the incident because of previous damage. It is not known whether the skidder operator would have survived the rollover if the seat belt had remained intact.

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