MINE SAFETY AND HEALTH ADMINISTRATION
Metal and Nonmetal Mine Safety and Health
Surface Nonmetal Mine
Fatal Machinery Accident
June 23, 2000
Brad Ragan Inc. Contractor I.D. (S06)
Salem, Roanoke County, Virginia
Salem Stone Corporation
Acco Stone Company
Christiansburg, Montgomery County, Virginia
ID No. 44-00189
Dennis A. Yesko
Supervisory Mine Safety and Health Inspector
Okey H. Wolfe
Mine Safety and Health Inspector
Daryl E. Porter
Mine Safety and Health Inspector
F. Terry Marshall
Robert C. Boring
Mine Safety and Health Specialist
Mine Safety and Health Administration
547 Keystone Drive, Suite 4
Warrendale, PA 15086-7573
James R. Petrie, District Manager
Gary W. McKee, tire company serviceman, age 57, was fatally injured about 10:55 a.m., on June 23, 2000, when he was struck by a 1,650-pound tire which fell from a hydraulic lift arm while being loaded onto the back of his service truck. The accident occurred because the tire was not gripped properly and the victim was not in the clear of the suspended tire.
McKee had a total of 30 years experience with Brad Ragan Inc.; he serviced tires on a routine basis at this mine. He had received training in accordance with Part 48.
The Acco Stone Company, a surface limestone mine, owned and operated by Salem Stone Corporation, was located in Christiansburg, Montgomery County, Virginia. The principal operating official was Jay O'Brien, Jr., president. The mine normally operated one, 11-hour shift a day, 5 days a week. A total of 40 persons was employed.
Limestone was extracted from a multiple bench quarry and transported by truck to the plant where it was crushed, screened and stockpiled for sale as construction aggregate.
McKee was employed by Brad Ragan Inc., a tire contractor. The principal operating official was Mark A. Goods, branch manager, Eastern Region. Brad Ragan, Inc., was a subsidiary of Goodyear Tire & Rubber Company and employed a total of 900 to 1,000 employees, of which 52 were employed in the Eastern Region. Brad Ragan Inc. provided a variety of tire services to industries in the Salem and Wise, Virginia areas.
The last regular inspection of Acco Stone Company was completed on January 21, 2000.
On the day of the accident, Gary W. McKee (victim) arrived at the mine site at about 10:30 a.m., and met with Robert Brown, superintendent, Acco Stone Company. Brown instructed McKee to change a tire on a R-50 Euclid haul truck and McKee went to the tire storage location to load a new tire onto his service truck.
At about 10:55 a.m., as Charles Womach, maintenance foreman was exiting the maintenance shop, he glanced in the direction of the tire storage area and saw a tire fall from the hydraulic lift arm of the tire service truck and strike McKee. Womach shouted for Dale Dalton to call for help while he rushed to aid McKee. McKee was pinned between the toolbox of the truck and the tire. Several persons joined Womach. They proceeded to lift and block the tire and remove McKee. McKee had incurred severe traumatic injuries to the chest, neck, and head. Faint vital signs were detected. Local authorities and emergency medical personal arrived at 11:05 a.m. McKee was transported to a local hospital where he was pronounced dead. Death was attributed to head, neck and chest trauma.
MSHA was notified at 11:33 a.m., on the day of the accident, by a telephone call from Helena P. Hester, safety and human resource coordinator, Acco Stone Company, to Samuel Bond, mine safety and health inspector, MSHA, Charlottesville, Virginia. An investigation was started the same day. MSHA's accident investigative team arrived at the mine on the morning of June 24, 2000, and began a physical inspection of the accident site with the assistance of personnel representing the mining company, the contractor, and the Commonwealth of Virginia, Department of Mines, Minerals & Energy. Employees of the mine operator and the contractor did not request, nor have, representation during the investigation. An order was issued pursuant to Section 103(k) of the Mine Act to ensure the safety of the miners and contractor employees until the affected area could be returned to normal operation.
� The tire service truck involved in the accident was a 2000 Sterling tandem truck, Vehicle Identification Number (VIN) 2FZXEECB9YAF59725, rated for a Gross Vehicle Weight (GVW) of 58,000 pounds. It was equipped with a truck-mounted crane located between the cab, and an 8-foot by 21-foot flat bed. A control station for the hydraulic crane was located behind the operator's cab on the driver's side, between the cab and the flat bed. The controls were accessible from ground level.
� The truck-mounted crane was a HIAB (Hydrauliska Industri AB) 250 P-1 hydraulic crane manufactured in 1999, Serial Number 250.352, with a Power Handler 8500 gripper-type tire handler attachment, Serial Number 110-IN0161-062399. According to Piedmont Service Truck representatives, the Series 8500 Power Handler was designed for a maximum tire weight of 8,500 pounds and the HIAB 250 P-1 was rated at about 178,000 foot-pounds. The crane's hoist controls were being operated by the victim using the radio-remote control unit at the time of the accident.
� The HIAB 250 P-1 hydraulic crane consisted of three main members on a rotating platform and had three controls for movement. The first member of fixed length, the inner boom, was hinge mounted to the rotating platform, or the boom platform. It was driven by a hydraulic torque motor (control #1). The second member of fixed length, the outer boom, was hinge mounted to the inner boom with a two-way hydraulic cylinder (control #2) connected to each member to provide movement between these two members. The variable length third member, the extension boom, was hinge mounted to the outer boom and had a two-way hydraulic cylinder (control #3) to provide movement between them. Controlling this extension boom's length (control #4) allowed 90-degree relative movement between the extension boom and the Power Handler 8500 gripper-type tire handler. A rotational platform was attached to the first member of the tire handler to allow 340-degree rotational movement of the tire gripper through the use of a hydraulic torque motor (control #5).
� Gripping force of the tire gripper pads was provided by two, two-way hydraulic cylinders (control #6). The width of the spread could be varied from 60 inches to 138 inches. The tire gripper pads could rotate about 90 degrees (control #7) through the use of two, two-way hydraulic cylinders, one for each gripper pad. All of the hydraulic cylinders, except the tire gripper rotation cylinders, had counterbalance load locking valves designed into the system. Counterbalance load locking valves were also designed into the torque motor systems.
� The truck mounted crane involved in the fatal accident was equipped with three independent methods for operating the crane's hoist controls. They could be operated manually from levers located on the machine in the operator's station or from levers on the remote control unit. The remote control unit functioned by a radio transmitter-receiver type of coupling to the power box or via direct cable attachment (tether) from the remote control unit to the power box. Appropriate interlocks were provided to preclude operation of the crane's hoist controls by more than one means at a time.
� The mine's tire stockpile was located on a grade adjacent to a haul road approximately 2� truck widths wide with over-the-road type truck traffic at the time of the accident. The service truck had been parked by McKee on the haul road approximately parallel to several stacks of tires, with the front end of the truck downhill to allow the crane to pick up the tire from the driver's side of the service truck (see attached sketch). The grade in this area was about 9 percent.
� The parking brake control in the operator's compartment was found in the applied position.
� The tire involved in the accident was brought to the mine site by the victim during a previous trip to the mine. He placed the tire in the storage area until it could be mounted onto the off-road haul truck. The tire was a new General CM150 24.00-35 E-4 tubeless off-highway tire with a 36-ply rating. It was being moved from the mine's tire storage area onto the service truck's flat bed in order to transport it to the haul truck that it was to be installed on. The tire was approximately 81 inches in diameter, had a tread width of about 24 inches, and weighed 1,625 pounds. It had been stored flat on top of another tire between two other stacks of tires. The contour of the ground in this area allowed the bottom tire's top sidewall to be approximately 30 inches off of the ground on one end with the opposite end (180 degrees on the tire's circumference) to be about 24 inches off of the ground. The stack to the left was three tires high and measured to be about 78 inches high. A single tire was lying to the right. The three stacks were placed close together. The bottom tires of each stack almost touched the adjacent tire. Tires on either side of the accident tire had visible scrape marks on them. These scrape marks were consistent with structural members of the tire handler attachment.
� The remote control unit was part of a CombiDrive Remote Control System manufactured by Olsbergs AB. The unit was marked with P/N-982 6564, S/N-6622 on a tag attached to the upper half of the control housing and had P/N-982 3883, S/N-0171 marked on a tag attached on the lower half of the housing. The remote control unit had sustained damage to two of the actuating levers during the accident. The levers that operate the functions for rotating the attachment (Power Handler 8500) and gripper pad rotation were broken off. These were found on the ground in the immediate area of the accident.
� The remote control system consisted of four basic parts: remote control unit with integral radio frequency transmitter; radio frequency receiver and decoder unit; power box; and, electro-mechanical interface. Seven of the machine's control functions (i.e., boom platform rotation, inner and outer boom relative movement, outer boom and extension relative movement, attachment tilt, attachments rotate, gripper pad rotation, and gripper pad clamping) were accessible from the remote control unit.
� The remote control unit had six self-centering operating levers which provided for bidirectional movement of the crane's hoist controls. Operational speed (100, 50 and 20 percent) of the seven hoisting functions was changed with a three-position toggle switch located on the remote control unit. This toggle switch was found in the 100-percent position during the field inspection. This toggle position permitted operating the hoist controls to obtain 100-percent maximum speed for hoist functions. The other two toggle positions allowed for slower movement, one-half and one-fifth of the maximum operational speed of the hoist functions, for precise positioning of the payload (tires, rims, etc.). A self-centering toggle switch on the remote control unit provided a method to extend the remote's capabilities to control up to twelve functions from the six lever controls. Functions one through six were utilized without depressing the function switch. The seventh function, gripper pad clamping, was accessed by depressing and holding the function switch on the remote control while simultaneously operating the lever otherwise utilized for the boom platform rotation.
� There was no evidence of moisture present inside any of the units comprising the remote control system. Most of the electronic circuits inside of the power box, the radio frequency receiver, and the decoder unit were encapsulated. The remote control unit had a rubber o-ring type of gasket positioned around the outer edges between the upper and lower housing parts. The electronic circuit boards were coated with a material to minimize problems with contamination inside of the enclosure.
� The hydraulic system was functionally tested using all three methods of operation. No hydraulic leaks were visually observed in the crane's hydraulic control system. No defects in the hydraulic system or the three control systems affecting function were detected. No visible loss of the tire handler's gripping force was detected during hydraulic tests in which a hydraulic pressure of about 20 MPa (2900 psi) was applied to the gripper cylinders. The hydraulic gripper pad rotation functioned and rotation was uniform between the two pads when normal tire loads were subjected on the cylinders.
� Functional testing of the crane's hoist controls included actuation of the seven control functions in all three operational modes: manual onboard control; radio-remote control; and cable-remote (tether) control. All of the crane's hoisting functions performed as expected without any signs of irregular motion or control disruption while each function was operated throughout its operational limits. Proper operation of the crane's hoisting functions at the three different operational speeds selectable from the remote control unit were also verified.
� The truck sustained no damage during the accident. Visual inspections and functional tests were conducted on the service truck crane's hydraulic system, the manual control system, the cable-remote control system, and the radio-remote control system.
� A number of safety features incorporated in the remote control system were verified during operation. Any circuit malfunction or interference causing missing or conflicting data encoding to be received by the onboard machine controls resulted in the immediate shutdown of all remote control hoisting functions. Proper operation of these safety features were confirmed by introducing intentional faults or circuit malfunctions while operating the remote control. After the intentionally induced problem was resolved and the control levers on the . remote control unit returned to their neutral (center off) position, remote control operation resumed by first actuating and then resetting the emergency stop button on the remote control unit.
� The radio-remote control system continued to function at a line-of-sight distance in excess of 600 feet, at which time the system automatically switched to another radio frequency channel without control disruption. Six different radio channels (transmit-receive frequencies) were user selectable from the radio-remote control unit and proper operation of the radio-remote control functions were verified for all channels. Attempts to create radio frequency interference of the radio-remote control system were unsuccessful. The operating frequencies and output power of the CB radio units utilized at the mine site were not sufficient to cause interference with the remote control's radio frequency signals or to cause disruption of the digital encoding-decoding of the radio-remote control system's data signals.
� The gripper pads of the clamp type tire handler were approximately 18� inches by 18� inches and contained two circular bolt patterns with acorn style nuts (acorn nut teeth) on the side that contacts the tire tread to aid in gripping the tire. Both circular patterns used eight equally spaced �-inch diameter SAE grade 8 bolts. The inner pattern was 9� inches in diameter while the outer pattern was 15� inches in diameter. The acorn nut teeth normally protruded about 1 inch from the surface of the gripper pads. The gripper pad surfaces were measured to be 71� inches apart following the accident.
� One set of gripper pad marks was found on the accident tire's tread during the field investigation. A cardboard model of the gripper pad was used to visualize the orientation of the gripper pads with respect to the tire tread and sidewall area prior to any gripper pressure being applied. This is shown in Photo #1, #2 and #3. Photo #2 and #3 show two different views of the same gripper pad orientation. (See Appendix D for Photos.)
� Eleven out of sixteen acorn nut teeth imprints were observed to have been left in the tire tread area of Photo #1 while about four of sixteen acorn nut teeth imprints were observed to have been left in the tire tread area of Photo #3. These imprints were used to simulate how the tire service technician had used the tire handler's gripper pads to pick up the tire. Photo #4 and #5 represent the accident tire gripped with the gripper pads similar to the marks found on the accident tire and the gripper pad surfaces about 71� inches apart. (See Appendix D for Photos.)
� Tests were conducted in which the gripper pads were rotated with the tire tread edge in contact with the ground to provide resistance to the rotational forces of the gripper pads. The gripper pads' orientation shown in Photos #4 and #5 slightly slipped on the gripper pad that does not have the circular bolt patterns over the entire area of the tread. No gripper pad slippage was observed during rotation resistance tests conducted when both gripper pads had both circular bolt patterns placed across the entire area of the tread. (See Appendix D for Photos.)
� Functional testing of the crane's hoist controls resulted in all of the hoisting functions performing as expected without any signs of irregular motion or control disruption while each function was operated throughout its operational limits. Also, intentionally induced remote control circuit malfunctions or interference causing missing or conflicting data encoding to be received by the onboard machine controls resulted in the immediate shutdown of all remote control functions. Radio frequency interference sufficient to cause unexpected activation or movement of the crane's hoist functions beyond complete shutdown was considered to be extremely unlikely at the mine's location. In this regard, the radio signals would need to be at the proper frequency and have the proper data encoding to cause any unintentional operation of the crane's hoist functions.
� Visual examination of the imprints left within the accident tire's tread area indicated that approximately 30 to 40 percent of the acorn nut teeth of one tire gripper pad were physically in contact with the tire tread when compared with the number of acorn nut teeth physically in contact with the other tire gripper pad, and that the resulting gripper pad forces were not applied through the tire tread's centerline. This contributed to the tire dropping out of the crane's tire gripper attachment.
The root cause of the accident was the failure of the tire contractor to ensure that employees stood clear of suspended loads. A contributing factor was the failure to adequately grip the tire with the hydraulic lift arm. One of the grip pads on the lift arm had only about 30 to 40 percent contact with the tire surface, allowing the tire to fall.
Order No. 7725515 was issued June 23, 2000, under provisions of Section 103(k) of the Mine Act:
A fatal accident occurred at this mine site on June 23, 2000, when a contract employee was attempting to load a tire (24.00-35) onto a service truck and was struck by the tire. This order is issued to assure the safety of all persons at this operation. It prohibits all activity at the tire storage area and the Sterling service truck used by contractor until MSHA has determined that it is safe to resume normal operations in the area. The mine operator shall obtain prior approval from an authorized representative for all actions to recover and/or restore operations to the affected area.This order was terminated on June 27, 2000. Conditions that contributed to the accident had been corrected and normal mining operations were allowed to resume.
Citation No. 7727664 was issued June 24, 2000, under provisions of Section 104(a) of the Mine Act for violation of 30 CFR 56.16009:
A serviceman for a tire contractor was fatally injured on June 23, 2000, when he was crushed by a 1,650 pound tire which fell from the hydraulic lift arm that he was using to load the tire onto his service truck. He was not in the clear of the suspended tire. One of the grip pads on the lift arm had only about 30 to 40 percent contact with the tire surface allowing the tire to fall.
Related Fatal Alert Bulletin:
A. Persons Participating in the Investigation
B. Persons Interviewed
C. Area Sketch
E. Accident Investigation Data Form numbers; 7000-50a, 7000-50b, 7000-50c and 7000-50e
Brad Ragan, Inc.
Mark A. Goodes, managerGoodyear Tire and Rubber Co.
James L. Johnson, assistant manager
Donald M. Hemming, safety, health, and environmental managerSalem Stone Corporation
Robert J. Brown, superintendentState of Virginia, Department of Mines, Minerals, and Energy
Helena P. Hester, safety & human resource coordinator
Gary E. Barney, supervisory inspectorMine Safety and Health Administration
Charles E. Smith, inspector
Dennis A. Yesko, supervisory mine safety and health inspector
Okey H. Wolfe, mine safety and health inspector
Daryl E. Porter, mine safety and health inspector
F. Terry Marshall, mechanical engineer
Robert C. Boring, electrical engineer
Jerry Vance, educational field services personnel
Brad Ragan, Inc.
Mark A. Goodes, managerPiedmont Auto and Truck Sales
James L. Johnson, assistant manager
Michael O. Yates, Sr., mechanic
Robert K. Smith, manager of Auto and Truck SalesSalem Stone Corporation
Robert J. Brown, superintendent
Helena P. Hester, safety & human resource coordinator
Charles Womack, maintenance foreman
Dewey Lawrence, mechanic
David R. Mans, lowboy driver