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Western District
Metal and Nonmetal Mine Safety and Health


Robinson Mine, I.D. No. 26-01916
Magma Nevada Mining Company
Morbark Sales Corp., Contractor ID - UTU
Ruth, White Pine County, Nevada

March 10, 1995


Ronald G. Ainge
Mine safety and Health Inspector


David A. Kerber
Mine Safety and Health Inspector

Western District Office
3333 Vaca Valley Parkway, Suite 600
Vacaville, California
Fred M. Hansen, District Manager


Robert Crawford MacDonald, a 31 year old equipment operator, was fatally injured at about 9:50 a.m., March 10, 1995, when the top in-feed yoke of a wood chipper fell and struck him. MacDonald, employed by Morbark Sales Corporation at the time of the accident, had one day of mining experience at this property.

Garry Day, MSHA Western District Assistant Manager, was notified of the accident by Robert Philips, Contracts Manager for Robinson Mine, at 10:50 a.m., March 10, 1995. An investigation was begun the same day.

The Robinson Mine was a surface copper and gold operation owned and operated by Magma Nevada Mining Company, Robinson Mining, Ltd. Partnership, located in Ruth, White Pine County, Nevada.

The mine and mill had about 550 employees and operated three shifts, seven days a week.

Primary activities at the mine site were directed toward the construction of a mill and settling pond. Some workers were involved in recovering gold, from previously mined ore, through a heap leaching process.

Magma had contracted with Ames Construction Inc. to build a large waste water impoundment area. Ames had then contracted with Morbark Sales Corp. to chip the trees and brush that were to be removed from the impoundment area.

Company Officials were:

Magma Nevada Mining Company, Robinson Mining, Ltd. Partnership

Harry C. Smith, President
Mian S. Khalil, Project Manager
Susan Stoddard, Safety Coordinator

Ames Construction Inc.
Richard J. Ames, President
Roger L. McBride, Director, Safety & Health
Michael Johnson, Division Manager
Richard Katsma, Project Engineer
Steve Park, Division Safety Manager
Guy Walkos, Project Safety Officer
Pete Smyle, Project Superintendent

Morbark Sales Corp.
Noval Morey, CEO Milan W. Robinson, Plant Manager

The operator required that all contractors conduct Part 48 training. Ames Construction, Inc. trained their employees as well as Morbark Sales Corp. employees according to a MSHA training plan approved December 9, 1994.

The last regular inspection at this property was conducted on November 25-26, 1994.


The accident involved an E-Z Mountain Goat Chipper, model number 50/36, serial number 1010, manufactured by Morbark Sales Corporation, Winn, Michigan. The chipper was being used to reduce trees and brush into chips in an area being converted to a waste water impoundment.

The E-Z Mountain Goat was powered by a 750 horsepower diesel engine. The chipper unit was mounted on a Caterpillar 325L undercarriage. It was equipped with a knuckle boom with a grappler on the end that picked up trees and brush and fed them into the chipper.

The in-feed area consisted of; a caterpillar chain feed conveyer on the lower portion of the chute, two in-feed wheels on each side of the opening, and a floating roller at the top. These components were used to guide the material into the chipper. The top roller was raised and lowered by hydraulic cylinders which put pressure on the trees and brush to control the feed rate.

Hydraulic drive motors provided forward and reverse motion to the conveyer and the feed wheels.

There was an area between the operator's cab and the outer edge of the in-feed chute that periodically clogged with wood chips and other material. This buildup of material had to be cleared because it would prevent the in-feed roller from being completely lowered. It was necessary for the roller to be in the lowered position to allow for the changing of the chipper knives. For the machine to work efficiently, the knives had to be changed or rotated at least once a day.

When the buildup occurred, the operator had to crawl into the in-feed area and remove the material by hand. Prior to entering this area, he/she was to place the in-feed roller and yoke assembly in the fully raised position and install locking pins. Wood chips or other debris on top of the chipper cover could prevent the yoke assembly from being completely raised and result in improper, or incomplete, insertion of the locking pins.

The locking assembly consisted of two pieces of one inch, inside diameter, metal tubing welded onto each side of the in-feed roller yoke. This tubing aligned with two more pieces of tubing that were welded to the chipper cover. To hold the in-feed roller in the upright locked position, two 1-inch metal pins were to be inserted into the tubing of the yoke and then into the tubing on the cover. The investigation determined that only one pin had been utilized.

The in-feed roller and yoke assembly that struck the victim was about 36 inches wide, 18 inches in diameter, and weighed approximately 2500 pounds.

The weather was rainy and cold with a high temperature of about 55 degrees.


Robert MacDonald reported for work at 6:00 a.m., his scheduled starting time. He operated the E-Z Mountain Goat Chipper without incident until about 9:30 a.m. At that time he radioed Pete Smyle, Project Superintendent for Ames Construction Inc., and asked him to have the service truck and compressor brought to his location so that he could change the knives on the chipper.

Smyles directed David DeMartin, Ames Construction Inc. maintenance foreman, and Dane Bjerky, Ames Construction Inc. oiler, to take the requested equipment to MacDonald. This was accomplished at about 9:40 a.m. DeMartin spoke with MacDonald for about five minutes and then he and Bjerky left the area.

At about 9:55 a.m., Gary Goodrich, Magma Nevada Environmental Manager, and five visitors went to the chipper area to observe the machine in operation. When they arrived, the engine was idling and MacDonald appeared to be working on the inside of the in-feed area. He was on his knees with his legs crossed at the ankles. After watching MacDonald for a couple of minutes and detecting no movement, Goodrich became concerned and climbed onto the machine.

He saw that MacDonald's head was pinned between the yoke of the in-feed roller and the frame of the feed chute. Goodrich shook and spoke to MacDonald but there was no response. He then went to the operator's cab, shut down the engine, and radioed for help.

Richard Katsma, Ames Construction Project Engineer/Manager, arrived at the accident scene at 10:00 a.m. He checked MacDonald for vital signs. Finding none, he radioed Magma's office and instructed them to call 911 for assistance.

The rescue unit from Ruth, Nevada arrived at the scene at 10:32 a.m., but were unable to resuscitate the victim. The White Pine County coroner arrived at 10:40 a.m. and pronounced MacDonald dead.


The primary cause of the accident was the failure to properly lock the in-feed yoke in the upright position prior to entering the chipper. A buildup of chips, and the lower pin holes being filled with material, may have prevented the yoke assembly from being locked in the fully upright position. Contributing factors may have been engine vibrations or the performance of work that dislodged a partially inserted pin.


Citation No. 3933668, 104(a), 56.14211(c). Issued to Morbark Sales Corp. 03/10/95

The operator of the Morbark 50136 E-Z Mountain Goat chipping machine, serial no. 1010, failed to properly secure the in-feed roller in the upright locked position while he was cleaning debris from between the feed chute and the operator's cab. The yoke assembly fell and struck the man in the left temple area causing a skull fracture resulting in a fatal injury.

Citation No. 3933669, 104(a), 56.14100(a). Issued to Morbark Sales Corp. 03/10/95.

The operator of the Morbark 50136 E-Z Mountain Goat chipping machine, serial no. 1010, was not doing a pre-shift examination of his equipment. During the accident investigation interview of the other operator it was determined that a pre-shift examination was not being conducted on the mobile equipment.

There was only one pin available on the machinery that could be used to lock the yoke assembly in the upright position. There were provisions for two pins. During a pre-shift inspection it should have been noted that one pin was missing.

Respectively submitted by:

/s/ Ronald G. Ainge
Mine Safety and Health Inspector

/s/ David A. Kerber
Mine Safety and Health Inspector

Approved by:

Fred M. Hansen,
Manager, Western District
Related Fatal Alert Bulletin:
Fatal Alert Bulletin Icon [FAB95M10]