Background

On a winter day in the Pacific Northwest, two rigging crew members were setting chokers. One of them went to retrieve chokers from a dropline under a motorized carriage.

Incident

As the one crew member was retrieving the chokers, the 5 ¼” by 5 ¼” metal exhaust rain flap fell from the carriage. After dropping about 100 feet, the flap struck and penetrated the right side of the other crew member’s hard hat. The 27-year-old choker setter was seriously injured. He lost consciousness upon impact. After regaining consciousness, he was driven to a hospital by a coworker. He suffered a skull fracture and traumatic brain injury, and an injury to his right shoulder. He spent several months recuperating before returning to work.

Unsafe Conditions

An inspection determined that the flap fell after the bolt came loose due to wear on the flap. The flap that fell was a replacement put on by the employer, and had a different design and was heavier than the original flap designed by the manufacturer.

Recommendations for Correction

• Maintain equipment in serviceable condition and inspect it before each work shift to ensure that is.
• Defective equipment in need of repair must be reported to management as soon as possible, and such equipment must not be used until repairs are completed if there is a possible safety hazard to employees.
• You must not make any modifications or additions that affect the capacity or safe operation of the equipment without written approval of the manufacturer or a qualified engineer.
• Replace motorized carriage exhaust flaps when they show signs of excessive wear.
• Train crews that flaps can come off, presenting a falling object hazard to workers below.
• Consider securing the exhaust flap with a chain tether to the exhaust guard to ensure that should the flap come loose from the carriage it will not fall to the ground.