Date of incident: October 2022
Notice of incident number: 2022197980026
Employer: Sawmill

Incident summary
Two workers at a sawmill were replacing drive belts on a piece of equipment. The workers were disconnecting the torque arm from another component of the drive unit for the equipment in order to install the new drive belts. When one of the workers removed the last bolt connecting the torque arm, the torque arm spun around and struck that worker, causing serious injuries.

Investigation conclusions

Cause

• Worker exposed to uncontrolled hazardous energy source. The equipment was not de-energized and locked out before the workers began the task of replacing the drive belts. When the worker removed the final holding bolt on the torque arm, significant stored energy (energy that resides or remains within the system but is not being used) was released, causing the torque arm to spin around and strike the worker.

Contributing factors

• Lack of hazard identification. The employer did not assess the equipment as required to determine whether there was potential for stored energy to remain in the system. Even though the employer had identified the need to lock out and de-energize other parts of the equipment, it failed to identify all components of the equipment as needing to be locked out and de-energized. A hazard identification and a risk assessment were not performed to identify and safely eliminate the exposure to the energy source on the equipment involved in the incident.
• Inadequate supervision and training. The employer did not provide adequate supervision. It allowed its workers to work on energized equipment that was not locked out and brought to a zero-energy state (when all energy sources have been removed or controlled, and all stored or residual energy has been discharged). The employer did not have a comprehensive system for identifying specific hazards related to the equipment or for ensuring that all hazardous energy was controlled and that this was verified prior to authorizing work on the equipment.
• Safe work procedures not followed and not adequate. The employer did have some written safe work procedures pertaining to lockout, but they were not followed. In addition, the employer did not have any written safe work procedures for locking out or de-energizing the torque arm.
• Manufacturer’s installation instructions not followed. The manufacturer’s installation instructions state that the reaction point of the torque arm (one end of the torque arm) must not be rigidly fastened; however, the employer affixed the reaction point of the torque arm with two bolts. If the reaction point had not been rigidly fastened, the position of the torque arm when energized would be different from when there is no stored energy in the system, thus providing a visual indicator that would allow workers to see that the system contained stored energy. The employer did not recognize that the torque arm was not installed according to the manufacturer’s specifications.

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