According to the agency, the issue of sudden unintended boom movements was first discovered on the loaders during an investigation of a 2001 fatality at a US metal/nonmetal operation.

“The CAT 988H loader involved in the accident, when tested cold (approximately 25 degrees Fahrenheit), would operate abnormally,” officials said in the alert.

“During raising of the loader arms, the arms would continue to rise after the lift control was released.

“When the operator tried to feather the arms down, the bucket would drop several feet.”

Caterpillar compiled new machine warm-up procedures to address the problem but the two said that risk to personnel could and should be evaluated when lifting or lowering objects, as a risk was posed with individuals nearby that the bucket could drop the object and injure personnel.

Also, when loading trucks, the bucket dropping could result in a jolt or injury to the truck driver and could also lead to significant equipment damage.

Until Cat determined a fix for the problem, administrative controls should be implemented.

This includes making sure the hydraulic fluid is warm, as per the OEM’s operating manual and ensuring that the bucket operation is reviewed before being put to work.

When in operation, all personnel must be clear of the machine and truck operators should remain in the truck cab or at a safe distance away as loading was performed.

Finally, complete training for all equipment operators is key, which includes all procedures for all equipment individuals operate.

“If any machine, equipment, or tool does not function as designed, immediately remove it from service and contact the manufacturer,” MSHA said, adding that all of these items should also be used within the manufacturer’s intended design capacity.