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UNITED STATES
DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION

REPORT OF INVESTIGATION

Surface Nonmetal Mine
(Crushed Quartz)

Fatal Powered Haulage Accident

July 4, 2001

Appalachian Tree and Stone (C345)
Spruce Pine, Mitchell County, North Carolina

and

Howell Contracting Company (H4K)
Spruce Pine, Mitchell County, North Carolina

at

Schoolhouse Mine Operation
Unimin Corporation
Spruce Pine, Mitchell County, North Carolina
Mine I.D. No. 31-000375

Accident Investigators

Mitchell Adams
Supervisory Mine Safety and Health Inspector

Michael C. Henley
Mine Safety and Health Inspector

Ronald Medina
Mechanical Engineer

Thomas J. Morgan
Mine Safety and Health Specialist

Originating Office
Mine Safety and Health Administration
Southeast District
135 Gemini Circle, Suite 212; Birmingham, AL 35209
Martin Rosta, District Manager


OVERVIEW


Michael V. Jackson, truck driver, age 44, was fatally injured on July 4, 2001. Jackson was descending a grade with a load of material when he apparently lost control of his haul truck, exited the cab and was run over by the rear wheels.

The accident occurred becausethe truck's service brakes had not been properly maintained and the victim had not been instructed relative to themanufacturer's operating procedures for this truck.

Jackson had a total of eight weeks experience, all with the same contractor, at this mine. He had not received training in accordance with 30 CFR Part 46.

GENERAL INFORMATION


Schoolhouse Mine Operation, a surface quartz operation, owned and operated by Unimin Corporation, was located at Highway 226n, about 5 miles from Spruce Pine, Mitchell County, North Carolina. The principal operating official was Carl F. Horvat, plant manager. The plant was normally operated two, 10-hour shifts a day, seven days a week. Total employment was 49 persons.

Quartz was drilled and blasted then loaded into trucks and hauled to the plant where it was crushed, washed, screened, sized and stockpiled. The product was then dried, packaged and sold for use in the aerospace industry and the manufacturing of electronic chips.

The victim was employed by Appalachian Tree and Stone, located in Spruce Pine, Mitchell County, North Carolina. Appalachian Tree and Stone was contracted to strip overburden and to construct a new access road to the mining area. The principal operating official was Blaine Biddix, owner. Appalachian Tree and Stone employed two persons and sub-contracted two additional employees from Howell Contracting Company, located in Spruce Pine, Mitchell County, North Carolina. The principal operating official for Howell Contracting Company was Dewitt Howell, Jr.. Five contract employees were working at the mine when the accident occurred. They normally worked 8 to 12 hours a day, 7 days a week.

The last regular inspection of this operation was conducted February 20-22, 2001. A regular inspection was conducted following the investigation.

DESCRIPTION OF ACCIDENT

On the day of the accident, Michael V. Jackson (victim), reported for work at 6:00 a.m., his regular starting time. He was assigned to operate a haulage truck, transporting overburden from the stripping area to the dump site.

Jackson had made 22 trips without incident. At about 2:45 p.m., Jackson was descending a hill with a load of material when apparently the brakes failed to slow the truck. It is believed that when Jackson realized he could not control the truck, he jumped from the truck and was run over by the rear wheels. The truck came to rest against a berm, 115 feet from whereJackson's body was found.

Andy Phillips, road grader operator for Unimin Corporation, was traveling in the opposite direction on the roadway when he saw the haulage truck coming down the hill. Phillips saw the truck strike the berm and the loaded bed of the truck overturn. Phillips found Jackson lying on the side of the roadway. Realizing Jackson was seriously injured, Phillips immediately summoned help. James Miller, mine supervisor, immediately went to Jackson and checked for vital signs but was unable to find any. Jackson was transported to the Watauga CountyCoroner's Office in Boone, North Carolina, where he was pronounced dead as a result of multiple trauma.

INVESTIGATION OF THE ACCIDENT

MSHA was notified of the accident at 4:00 p.m. on July 4, 2001, by a telephone call from Richard Sparks, health, safety and security supervisor for Unimin Corporation, to Cindy L. Kinard, safety and health specialist. An investigation was started that day. An order was issued under the provisions of Section 103(k) of the Act to ensure the safety of miners.MSHA's accident investigators traveled to the mine, made a physical inspection of the accident scene, interviewed employees, and reviewed conditions and work procedures at the time of the accident. MSHA conducted the investigation with the assistance of both mine and contractor management and employees. The miners did not request nor have representation during the investigation.

DISCUSSION

  • The haulage road, where the accident occurred, went from the stripping area to the dump site for a distance of approximately 3/10ths of a mile, with grades varying from 9.8 to 14.9 percent. The road was an average of 30 feet wide with earthen berms, approximately 4 feet high, on both sides.

    Jackson's body was found 530 feet from the crest of the roadway. The truck continued traveling another 115 feet from where the victim was found.

  • The truck involved in the accident was a Moxy MT30, six-wheel drive, articulated dump truck with a 30-ton capacity. The truck was powered by a Scania, DSC9, 6-cylinder, diesel engine rated at 263 horsepower. The gross vehicle weight was 100,400 pounds. The hour meter indicated 1130.5 hours of operation. The tractor portion of the machine had one axle and the trailer had two axles. The truck was leased by Howell Contracting Company. No Operating and Maintenance Manual for this haul truck could be located on the mine property.

  • The trailer overturned onto its right side as a result of the accident and a brake line from the rear master cylinder to right rear wheel was slightly dented, but was not leaking. The tractor portion of the truck did not overturn and no accident related damage was found. Witnesses reported that the engine was still running after the truck came to rest following the accident.

  • The controls were found in the following positions: the gear shift lever was in the forward, drive (D) position, the hydraulic retarder lever was fully back toward the operator in the fully applied position, the park brake control was fully back toward the operator in the applied position, the truck dump body lever was in the full forward position which was the dump body down position, the interaxle lock was disengaged, the key was in the off position (co-workers reported the engine was turned off after the accident), the windshield wipers were off, the air conditioner was on, the service brake pedal, accelerator pedal, and steering wheel were operating properly.

  • The truck was equipped with an electronically controlled automatic transmission with six forward speeds and three reverse speeds. The operator could select 1, 2, 3, and D in forward, and 1, 2, and 3 in reverse. There was also a neutral position. According to the Operating and Maintenance Manual for the truck, with the transmission lever in D, the transmission would automatically shift between first and sixth gears according to truck speed and engine RPM. When placed in the 1, 2, or 3 position, the transmission would not shift into a higher gear than the one selected.

  • The truck was equipped with an engine exhaust retarder and a hydraulic transmission retarder. The engine exhaust retarder was designed to engage whenever the throttle pedal was released. There were no other operator controls for the exhaust retarder. The hydraulic transmission retarder was also designed to engage upon throttle release, provided the hydraulic retarder control lever was in the applied position. The Operating and Maintenance Manual stated that when either retarder was engaged, the transmission would not shift to a higher gear. However, if the operator pushed the throttle pedal while descending the grade, the transmission could up shift at these times. Mine personnel, who drove other Moxy MT30 trucks on the same grade with the same load reported that the trucks shifted into 4th or 5th gear while descending the grade, if the transmission was in drive and the speed was not controlled. In higher gears, the effectiveness of the retarding systems to slow the truck was much less than in lower gears. No defects were found with the engine exhaust brake or hydraulic retarder systems.

    The applicable retarder chart in the Operating and Maintenance Manual indicated that, based on the 9.8 to 14.9 percent grade the truck was traveling and the load the truck was carrying, the highest permissible travel gear was 3rd when descending the grade.

  • The service brake system consisted of air-over-hydraulic, caliper-disc brakes at each of the six wheels. The front and rear circuits were separated and each circuit had its own air and fluid reservoirs. Each of the brake actuators that developed the hydraulic braking pressure consisted of an air chamber fixed to a hydraulic master cylinder. When the air chamber was pressurized, a rod extended from it, which forced the master cylinder piston to pressurize the brake fluid and activate the brake caliper pistons. The manual also stated that the operating air pressure for the brake system was from 99 to 113 pounds per square inch gauge (PSIG).

    Two separate air chamber/master cylinder actuators were provided. One for the front brakes (tractor) and one for the rear brakes (trailer). Each of the two front wheels on the tractor was provided with two brake calipers and each of the four rear wheels on the trailer was provided with one caliper. This made a total of eight calipers. The service manual for the truck stated that each of the calipers provided the same amount of braking torque when applied. Examination of the brake pads and the discs showed they were in compliance with the manufacturer's specifications.

    The parking brake system consisted of a spring-applied, air-released, caliper-disc on the trailer drive shaft. The parking brake was activated by a lever in theoperator's compartment. To prevent driving through an applied park brake, the truck design included a transmission/park brake interlock that would place the transmission into neutral when the parking brake was applied.

  • After the trailer was up righted, the truck engine was started and air pressure built up in both the front and rear brake system air tanks. The cut-in and cut-out points of the compressor were 95 PSIG and 110 PSIG. The truck was inspected for air leaks and none were found.

    The brake fluid level in the front master cylinder reservoir, on the tractor portion of the truck that did not turn over, was 2 inch below the minimum level marked on the reservoir. With 95 - 110 air pressure and the service brake fully applied, the output brake fluid pressure from the front master cylinder was 0 PSIG. This master cylinder was disassembled and the piston cup seal, which pressurized the brake fluid for the front service brake system, was found to be torn in two pieces. The front service brake system was therefore nonfunctional and provided no braking force.

    The pre-accident brake fluid level in the rear master cylinder reservoir could not be accurately determined since the trailer came to rest on its side which allowed brake fluid to escape through the vented cap. The output pressure from the rear brake master cylinder was approximately 1500 PSIG with full service brake application and an air pressure between 95 and 110 PSIG. The brake fluid pressure held steady for two minutes while the operator held the service brake pedal applied. Allowing for measurement tolerances this pressure was within the expected range.

    Four out of the eight service brake calipers on the machine were not functional. This severely reduced the braking capability of the truck.

  • Heat damage was apparent at the parking brake caliper. A four inch long section of the soft plastic casings that separately covered the electric and air lines routed directly above the parking brake caliper were charred black. After the casings were removed and examined, it was determined there was much less heat damage inside the casings than outside. There was no evidence indicating the heat source was electrical.

    The damage appeared recent since there was dust and mud on the rest of the plastic casings but not on the charred area. Soot was found on the parking brake disc and the linings appeared burnt. Witnesses reported a strong odor of overheated brake linings immediately after the accident.

    The park brake control lever was found in the applied position. On site testing showed that this lever did not automatically shift to the applied position even in the event of a complete loss of air pressure. (This indicated the system worked as designed, however, the spring-applied parking brake caliper itself, did apply upon loss of air pressure as designed.) Based on this evidence, it can be concluded that Jackson applied the parking brake, causing the brake to overheat as the truck continued down the hill.

    The truck was designed such that the transmission would shift into neutral when the parking brake was applied. This interlock was tested and functioned according to design.

  • No defects were found with the steering system. The seat belt was found fully retracted and it latched when the two ends were buckled. Weather on the day of the accident was dry.

  • Evidence indicated that Jackson had the transmission selector in drive as he descended the hill. This allowed the transmission to up-shift, negating the retarder. As the truck gained speed, Jackson applied the parking brake, which shifted the transmission into neutral, causing the engine brake and hydraulic retarders on the truck to become completely ineffective in slowing the machine.

    CONCLUSION

    The primary cause of the accident was failure to properly maintain thetruck's service brake system in operable condition. The following root causes were identified: failure to establish procedures requiring safety defects to be reported, recorded and promptly corrected and the failure to train equipment operators in the correct operation of the haul trucks.

    VIOLATIONS

    Unimin Corporation

    Order No. 77797584 was issued on July 4, 2001, under the provisions of Section 103(k) of the Mine Act:
    A fatal accident occurred at this operation at about 2:45 p.m. on July 4, 2001, when a contract haulage truck operator exited his truck and was run over by same truck. This order is issued to assure the safety of persons at this operation until the mine or affected areas can be returned to normal operations as determined by an authorized representative of the Secretary. The mine operator shall obtain approval from an authorized representative for all actions to recover persons, equipment, and/or return affected areas of the mine to normal.
    This order was terminated on July 20, 2001. Conditions that contributed to the accident have been corrected and normal mining operations can resume.

    Appalachian Tree and Stone

    Citation No.6076203 was issued on July 20, 2001, under the provisions of 104(a) of the Mine Act for violation of 30 CFR 46.3(a):
    A fatal accident occurred at this operation on July 4, 2001, when a contractor employee lost control of the haulage truck he was operating and was crushed beneath the rear wheels. The contractor had not developed or implemented a written plan for training new miners, newly-hired experienced miners, training miners for new tasks, annual refresher training or site specific hazard awareness training.
    This citation was terminated on July 23, 2001. A training plan had been developed.

    Citation No. 6076204 was issued on July 20, 2001, under the provisions of 104(d)(1) of the Mine Act for violation of 30 CFR 46.5(a):
    A fatal accident occurred at this operation on July 4, 2001, when a contractor employee lost control of the haulage truck he was operating and was crushed beneath the rear wheels. The victim was employed on May 7, 2001, and was not provided with the required 24 hours of new miner training or assigned work where an experienced miner could observe that the employee was performing the work in a safe manner. The victim had no prior mining experience. This constitutes more than ordinary negligence and is an unwarrantable failure to comply.
    This citation was terminated on July 24, 2001. Requirements of Part 46 has been explained to the contractor and all newly hired employees will be trained accordingly.

    Citation No. 6076205 was issued on July 20, 2001, under the provisions of 104(a) of the Mine Act for violation of 30 CFR 56.14100(d):
    A fatal accident occurred at this operation on July 4, 2001, when a contractor employee lost control of the haulage truck he was operating and was crushed beneath the rear wheels. Defects existed on the haulage truck that affected safety and were not either reported to, or recorded by, the operator. Pre-shift examination records indicated the last examination was conducted June 28, 2001. Daily operational records indicated the haulage truck had been operated daily from June 30, 2001, to July 4, 2001.
    This citation was terminated on July 24, 2001. Pre-shift inspections are being conducted and deficiencies are being reported and recorded.

    Howell Contracting Company

    Citation No. 6076202 was issued on July 20, 2001, under the provisions of 104(a) of the Mine Act for violation of 30 CFR 56.14101(a)(1):
    A fatal accident occurred at this operation on July 4, 2001, when a contractor employee lost control of the haulage truck he was operating and was crushed beneath the rear wheels. The service brakes on the Moxy, MT 30 haulage truck were not adequate. The piston cup seal for the front master cylinder, which pressurizes the hydraulic side of the front service brake system, was torn in two pieces and rendered the front brakes non-functional.
    This citation was terminated on July 24, 2001. The truck has been removed from the property.

    Related Fatal Alert Bulletin:
    Fatal Alert Bulletin Icon FAB01M19



    APPENDIX A

    Persons Participating in the Investigation

    Unimin Corporation
    Richard Sparks .......... health, safety and security supervisor
    David Duffy .......... mine superintendent
    Appalachian Tree and Stone
    Blaine Biddix .......... owner
    Clay Lusk .......... equipment operator
    Howell Contracting Company
    Andy Greene .......... foreman/equipment operator
    North Carolina Department of Labor
    Allen Greene .......... inspector/investigator
    Mine Safety and Health Administration
    Mitchell Adams .......... supervisory mine safety and health inspector
    Michael C. Henley .......... mine safety and health inspector
    Ronald Medina .......... mechanical engineer
    Thomas J. Morgan .......... mine safety and health specialist
    APPENDIX B

    Persons Interviewed

    Unimin Corporation
    Richard Sparks .......... health, safety and security supervisor Andy Phillips .......... grader operator
    Appalachian Tree and Stone
    Blaine Biddix .......... owner Clay Lusk .......... equipment operator
    Howell Contracting Company
    Andy Greene .......... foreman/equipment operator Mark Greene .......... equipment operator