PHYSICAL FACTORS INVOLVED

The accident occurred in the parking lot which was graveled and relatively level. The lot was located just south of the maintenance shop. The equipment involved was a 1977 Caterpillar 988B wheel loader. The bucket and control arm assembly had been replaced with a Teledyne rock breaker boom attachment.

Examination and testing of the mechanical control linkages and the hydraulic valves/components suspected to contribute to the accident showed the following:

1. The 1/4 inch diameter control rod that connects the hand control lever for the swing movement of the boom to the control valve was completely broken. The broken sections of the rod were corroded indicating that the rod had been broken prior to the accident. The broken rod rendered the hand lever control for the boom swing movement nonfunctional.
   
2. The linkage connections for the Teledyne controls, including the clevis pin connections and the ball socket connections, were corroded to the extent freedom of movement was impaired. When the hand control levers for the boom and the head angle were operated, the movement was resistant and the control valves did not return to the centered position.

   As part of the investigation, the linkages were disconnected from the control valve bank and the control valves and the linkages were operated by hand, independent of each other, to isolate the resistant movement and loss of self centering ability. The control valves operated freely and smoothly by hand without any sticking or binding and quickly returned to their centered position. Resistance was felt when the linkages were moved independent of the control valves, showing that the resistance was caused by the contaminated and corroded linkage connections.

   The cab was contaminated throughout with a white powder substance thought to be chemical residue from an ABC-type fire extinguisher that vandals had sprayed in the cab of the machine.
   

3. The rear portion of the linkage for operation of the boom stick was tightly contacting the cab wall liner and was not functional in the retract position. That is, the hand lever control could not be moved in the forward direction, resulting in the inability to retract the stick of the boom. Visual examination showed that the cab liner was not properly attached. Several attaching bolts were missing and others were not completely tightened, allowing the cab liner to pull away from the cab structure and contact tightly against the linkage that operates the boom stick.
   
4. The support structure where the hand control levers for the Teledyne boom components are mounted was hinged in the rear and could be raised upward. When raised to the uppermost point, the linkage for the controls bound against the support causing the control valves to move from the centered position.

The loader had been at the mine since October 1997, and had been used once on a trial basis. It had not suited the needs of the mine operator and had been parked unused for close to six months. The loader remained at the mine site during this time, awaiting Hanson to come for it.

DESCRIPTION OF ACCIDENT

On the day of the accident, Lowell Hanson (victim) arrived at the mine at about 8:30 a.m. He met Ralph Ehlert, mechanic, George Bevier, truck driver, and Nicholas Bevier, escort driver, all had recently been hired by Hanson to assist in transporting the loader. The battery of the machine was dead, so another loader parked beside it was used to jump- start the dead battery. The machine was started and backed up a short distance from the stored location.

With the engine idling, Ehlert proceeded to center the boom from the stored position, which was slightly to the right of center. Ehlert stated that the mechanical linkage rod that operates the swing movement was broken, so he used a pry bar approximately 15 inches long to move the swing control valve. In order to use the pry bar, he raised the hinged support structure where the hand lever controls that operate the Teledyne boom components were mounted, and held it in position with his upper left arm. He then placed one end of the pry bar directly on the swing control valve and used the support bracket for the linkage assembly as the fulcrum. Ehlert stated that he was unsure of which direction to move the valve to swing the boom to the left. His action resulted in the boom swinging farther to the right, crushing Hanson against the other loader. The valve stuck in the right swing position and Ehlert had to pry in the opposite direction to free the stuck valve. This resulted in the boom swinging completely to the left against the stop.

Nicholas Bevier ran to the mine office for help. A paramedic unit arrived a short time later and Hanson was pronounced dead at the scene by the county coroner.

CONCLUSION

The primary cause of the accident was the failure to repair the linkage and controls prior to attempting to operate the boom attachment.

VIOLATIONS

Order No. 7823030 was issued on September 18, 1998, under the provisions of Section 103(k) of the Mine Act:

A fatal accident occurred at this operation on September 18, 1998, when an employee was pinned between two 988B front-end loaders. This order is issued to assure the safety of persons at this operation until the mine or affected areas can be returned to normal mining operations as determined by an authorized representative of the Secretary.

A citation for violation of 30 CFR 56.14100(c) was not issued to Procon Group as Lowell Hanson (victim) was the sole employee of the company and did not survive the accident.

Related Fatal Alert Bulletin:
FAB98M40