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UNITED STATES
DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION

COAL MINE SAFETY AND HEALTH

REPORT OF INVESTIGATION

Surface Coal Mine


Fatal Powered Haulage Accident
July 29, 2000


Black Butte and Leucite Hills Mines
Black Butte Coal Company
Point of Rocks, Sweetwater County, Wyoming
ID No. 48-01180


Accident Investigators

William E. Vetter
Coal Mine Safety and Health Specialist (Health)

Eugene D. Hennen
Mechanical Engineer

Darren J. Blank
Civil Engineer

Dennis Tobin
Training Specialist


Originating Office
Mine Safety and Health Administration
District 9
P.O. Box 25367
Denver, Colorado 80225-0367
John A. Kuzar, District Manager


Report Release Date: 01/16/2001
Revised Date: 04/24/2001




THIS REPORT WAS REVISED TO ADDRESS THE FOLLOWING CORRECTIONS:

1. The sketch on page 1 was revised to correctly show the location of the soil samples that were taken by MSHA during the investigation.

2. Page 5, paragraph 2 was changed to remove references that the truck was steered toward the left shoulder. The report now states that the truck veered toward the left.

3. The last sentence on Page 7, paragraph 2 was revised to state that an oil sample was taken from the steering circuit hydraulic oil tank of the truck involved in the accident.

4. Page 8, Item 6 was revised to correctly indicate that the tractor had dual wheels on the rear axle.

5. Page 9, Item 7 was revised to correctly state that the trailer had dual wheels on the axle.

6. The last sentence on Page 10, Item 9 was added to state that the steering hose, which became damaged, was installed on the truck after it was delivered to the mine. This determination was made since the truck was delivered to the mine in the second quarter of 1979 and the hose was manufactured in the third quarter of 1979.

7. Page 10, Item 10 was revised to refer to working pressures instead of maximum pressures, and additional information on the steering circuit was included.

8. Page 10, Item 11 was changed to correctly refer to the locations where the soil samples were taken.

9. The Conclusion on Page 14 was rewritten to state that the soil sample tests determined that the loss of steering oil occurred prior to the truck hitting the haul road berm.




OVERVIEW


On Saturday, July 29, 2000, at approximately 9:00 p.m., Claud C. Butler, age 45, was fatally injured in a surface powered haulage accident while operating a haul truck at the Black Butte and Leucite Hills Mine. Butler was driving a loaded Euclid haul truck, Model CH-150, Unit No. 19-7115 (#15), from Pit No. 10 to the No. 10 hopper, a distance of approximately 6.5 miles. Troy Householder, another haul truck driver returning to the pit, was the last to see Butler before the accident. This was at the crest of a hill on the Ramp No. 2 haul road from Pit No. 10.

From the time he was last seen, Butler's truck traveled approximately 0.4 miles from the crest of the hill to the intersection of the Ramp No. 1 and Ramp No. 2 haul roads. As Butler's truck negotiated a right-hand curve to enter the intersection, it veered slightly to the left leaving the roadway, crossed the Ramp No. 1 haul road, traveled through a 7.5-foot high berm, turned left, and traveled in a semi-circle, coming to rest at the edge of the Ramp No. 1 haul road. Butler was not wearing a seat belt and was ejected through the windshield of the operators cab. He landed and remained on the external truck decking. Butler had nine years, twenty-eight weeks mining experience. Other than having driven a Euclid haul truck on two occasions in the last nine months, he had not driven one for several years.

The direct cause of the accident was a ruptured hydraulic steering hose which caused Butler to loose steering control of the truck. Testing of the steering system showed that the truck would not steer to the right. Visual examination showed that the loss of steering was caused by loss of hydraulic pressure through a hole in a worn steering hose. The damaged steering hose was worn from rubbing against the frame of the coal hauler. This hose was not secured in the area of the damage to prevent it from rubbing the frame of the coal hauler. Soil samples tested for oil compatible with the steering oil from the truck indicated that the loss of steering oil occurred prior to the truck impacting the haul road berm. Contributing factors were the victim not wearing a seat belt; failure to stop the truck before impacting the berm; and the limited operating time of Butler on the Euclid truck in recent years.

GENERAL INFORMATION


The Black Butte and Leucite Hills Mine is a surface coal mine located 38 miles east of Rock Springs, Sweetwater County, Wyoming. The mine produces sub-bituminous coal. The Black Butte operation is located south and adjacent to Interstate 80. The Leucite Hills property adjoins Black Butte but is located to the north of Interstate 80. The mine is operated by Black Butte Coal Company, a joint venture by Level III/Anadarko. The mine has two active pits, No. 8 and No. 10.

Coal production began in February 1979. Coal is mined in Pit No. 8 from the "D", "C", and "A" seams of the Almond formation. The combined average thickness of these seams varies from 19 to 24 feet. In Pit No. 10, the "C" seam of the Union formation is mined with a maximum thickness of 28 feet. At the present mining location in Pit No. 10, the "C" seam splits forming the "C1" and "C" seams for a total average thickness between 18 and 24 feet. The parting between these two seams ranges from 4 inches to 15 feet. The overburden thickness is 80 feet at Pit No. 8 and 150 feet at Pit No. 10.

Top soil is removed by bulldozers and the remaining overburden is drilled and blasted and removed by Bucyrus-Erie, Model 1570, draglines. Once the overburden has been removed, the coal is drilled and blasted. It is then loaded with a Caterpillar, Model 992-G, front end loader onto either Euclid, Model CH-150, bottom dump or Caterpillar, Model 777, end dump haul trucks to be transported to "near pit" hoppers. The haulage distance from Pit No. 8 to No. 8 hopper is either one mile or three miles depending on which of the two ramps are used. Haulage distance from Pit No. 10 to No. 10 hopper is six and one half miles. From the hoppers the coal is transported by conveyor belt to a central processing plant. At the plant, coal passes through a primary and secondary crusher system, yielding a 2-inch minus product. From this point, it is conveyed to storage silos to be loaded onto trains or over the road trucks and transported to the Bridger Power Plant or Solvay Minerals, Inc., a trona processing plant.

Coal is produced at an average rate of 9,000 tons daily. The mine operator employs approximately 145 administrative and mining personnel. Two contractors employ a combined total of 14 technical employees. Mining operations are scheduled for two 12-hour shifts, seven days a week. Salaried supervisors are scheduled on two overlapping shifts five days a week, Monday through Friday. Hourly employees selected as leadmen cover the supervisory duties for eight hours every day Monday through Friday. Leadmen are also assigned to supervise the work force from 9:00 p.m. Friday to 5:00 a.m. Monday.

The last Mine Safety and Health Administration (MSHA) inspection (AAA) prior to the accident was completed on February 11, 2000. The NFDL incident rate (excluding office workers) for this mine was 5.73 for the 2nd Quarter, 2000, and 1.73 for 1999, compared to the National surface NFDL incident rate of 2.23 for the 2nd Quarter, 2000, and 2.03 for 1999.

The principal officers at the mine at the time of the accident were:
William Hill ............... Mine Manager
Steven Mullaney ............... Mine Superintendent
Lyn Caudill ............... Equipment Superintendent
Donald Kollekowski ............... Safety Supervisor
Howard Starr ............... Planner Superintendent
James Vugrinec ............... Maintenance Planner
The highest levels of supervision at the mine when the accident occurred were:
William Frost ............... Leadman/Grader Operator
Larry Downs ............... Leadman/Equipment Operator
DESCRIPTION OF THE ACCIDENT


On Saturday, July 29, 2000, at approximately 5:55 p.m., production crew members received their job assignments from William Frost, leadman/grader operator, at the main shop. The crew was instructed by Frost to load and haul coal from Pit No. 10 to the No. 10 hopper area. Coal was to be loaded with a Caterpillar, Model 992-G, front-end loader into bottom dump Euclid, Model CH-150, haul trucks. After receiving their assignments, the miners left the shop area to travel to their respective jobs. Frost went about the task of setting up portable light plants for night operations. Light plants were to be set up at Pit No. 10 and a stock pile area located near No. 10 hopper.

The weather had been dry and seasonably warm during the day shift with no abnormal conditions reported. With the weather continuing as it had been during the day shift, a water truck driver on the night shift had applied water to the haul road from Pit No. 10 to No. 10 hopper. The haul road was reasonably well maintained. However, there were a couple of isolated locations containing what were locally called "blow holes". These were depressions in the road where the hard packed road surface had broken down exposing the softer sub-surface material. At these locations, the blow holes occupied a small area of the haul road width.

Normally, Pit No. 10 was accessed by Ramps No. 1 and No. 2. However, only Ramp No. 2 was being used due to the stage of mining, which prevented the use of Ramp No. 1. Coal hauling operations commenced soon after the crew members received their instructions and progressed normally as a fleet of six trucks hauled coal out of Pit No. 10. Frost, after positioning light plants at Pit No. 10, traveled to the No. 10 hopper area to install light plants there.

Shortly before 9:00 p.m. Claude Butler, victim, operating Euclid, Model CH-150, coal hauler, Unit No. 19-7115 (#15), topped the crest of a hill on Ramp No. 2. Hauling his third load of coal from Pit No. 10, he met Troy Householder driving another Euclid, Model CH-150, coal hauler, returning empty to the pit. After passing Householder, Butler drove his truck from the crest of the hill another 0.4 miles. He successfully negotiated several curves as he traveled toward the intersection of Ramp No. 2 with Ramp No. 1.

As Butler approached the right-hand curve leading into the intersection, tire tracks indicated that the truck veered toward the left shoulder of the road, avoiding a direct hit with a "blow hole". The tire tracks then indicated the truck veered to the right as if to negotiate the curve. After the right side tires passed through the "blow hole", the truck traveled in a straight direction for a short distance, then veered slightly to the left. Continuing at this angle, the truck traveled along the left shoulder of the road for approximately another forty to fifty feet. Leaving the road, the truck passed over a small triangular shaped area formed by the Ramp No. 1 road converging with the Ramp No. 2 road, and down a slight embankment. After the truck entered and crossed Ramp No. 1, it impacted a berm 7.5 feet high, which ejected Butler from the operators compartment through the windshield. He landed and remained on the truck's deck at the front right corner of the operators cab. The truck continued through the berm on a relatively flat area and made a sharp left turn. It traveled in a semi-circle and came to a stop at the inclined shoulder of the Ramp No. 1 haul road.

Approximately five minutes later, the haul truck driver following Butler saw Butler's truck setting at the east end of the berm, but discounted any thought of a problem. Thinking that Butler had intentionally driven to this location and parked his truck, the driver continued on to the No. 10 hopper. Jason Roberts, the driver of a second truck, crested the hill in view of the accident approximately ten to twelve minutes after Butler had gone through the berm. From the top of the hill, Roberts noticed Butler's truck stopped at the end of the berm. As he approached the accident scene, he noticed a fresh opening in the earth berm and stopped to investigate. After parking his truck and contacting Frost by radio, Roberts mounted Butler's truck from the damaged ladder at the front. Finding Butler on the decking outside of the truck cab, Roberts checked for a pulse and found none. The truck engine was still running so he reached through the front window opening and turned off the ignition switch. As the engine stopped the truck began to roll backwards. To stop the truck, he again reached through the window opening and set the trailer brakes.

Soon after Roberts had turned off the truck engine, Russ Noble, lube truck driver, arrived at the scene. Noble, who was trained in Basic Emergency Care (BEC), confirmed Roberts' evaluation of Butler's condition. Other rescue personnel began arriving to help remove Butler from the truck. The mine ambulance was summoned to transport Butler to a hospital in Rock Springs, WY. En route Butler was transferred to the Vase Ambulance Service ambulance and taken to Memorial Hospital of Sweetwater County where he was pronounced dead on arrival.

INVESTIGATION OF THE ACCIDENT


On Saturday, July 29, 2000, at 10:00 p.m., William Denning, District 9 Staff Assistant, was notified of the accident. Michael Havrilla, MSHA inspector assigned to the Craig, CO field office, arrived at the mine at 7:15 a.m., July 30, 2000, to secure the area and take photographs of the scene. Preliminary information was collected at this time. Detective, Marc Furman, from the Sweetwater County Sheriff's Office, investigated the accident on July 30, 2000. Assigned to investigate the accident for MSHA were: team leader, William E. Vetter, Mine Safety and Health Specialist from Delta, CO; Eugene D. Hennen, Mechanical Engineer, from MSHA Technical Support, Triadelphia, WV; Darren J. Blank, Civil Engineer, from MSHA Technical Support, Pittsburgh, PA; and Dennis Tobin, Educational Field Services Specialist from Vacaville, CA. Also participating in the investigation were Donald G. Stauffenberg, Wyoming State Inspector, and Rudy King, Deputy State Inspector, both from Rock Springs, WY.

The MSHA accident investigation team arrived at the mine on July 31, 2000. A pre-investigation conference was held with William Hill, Mine Manager; Donald Kollekowski, Safety Supervisor; and Frank Ratajski, Peter Kiewit & Sons, Corp., Safety Manager. Following this conference, the investigation team traveled to the accident scene accompanied by Kollekowski. The accident scene and haul truck were visually examined and video camera filming was done. Measurements and calculations of the material removed from the berm by the truck were made. Grades, measurements, and curvatures of the road from the crest of the hill to a point beyond the accident were recorded.

On Tuesday, August 1, 2000, the MSHA investigation team arrived at the mine joined by Dennis Tobin, Educational Field Services Specialist (MSHA) from Vacaville, CA. Hennen traveled to the accident scene accompanied by company officials while the remaining investigation team held interviews with employees assigned to the July 29, 2000, night shift production crew. Copies of equipment maintenance logs and training records were obtained and reviewed. During Hennen's investigation activities at the scene, a ruptured hydraulic steering hose was discovered. An attempt to turn the front wheels to a straight position with the damaged hose in place failed.

On Wednesday, August 2, 2000, the investigation team returned to the accident site. Soil samples with evidence of oil/fluids were collected from the path of the truck prior to the truck colliding with the berm. The soil samples were tested by the Touchstone Research Laboratory, Ltd., One Millennium Centre, Triadelphia, WV 26059, to determine the identity of the oils/fluids in the soil samples. Test results are included in the Discussion factors. Tests were also conducted to determine the effects the damaged hydraulic steering hose had on the braking system. These tests showed no negative effects. The damaged hose was removed from the truck and collected as physical evidence. After analyzing the soil samples that were collected from the truck path, MSHA decided that it was unnecessary to conduct tests on the damaged hose.

On Thursday, August 3, 2000, the investigation team traveled to the accident site to conduct additional tests. These tests included: testing the engine retarder; parking brake pull test using a tension link; testing hydraulic pressure and reactionary time of the braking and steering systems during various stationary braking or steering maneuvers; and a visual test of the steering system while simulating a damaged hydraulic steering circuit. Oil samples were collected from the oil supply units mounted on the lube truck used to service the haul trucks and from the steering circuit hydraulic oil tank of the truck involved in the accident.

DISCUSSION


1. The accident occurred on the Ramp No. 2 haul road, which served as a main haulage route from Pit No. 10 to the No. 10 hopper. The road was approximately 6.5 miles long and consisted of a relatively smooth surface of well-graded material ranging in size from sand to gravel. Approximately 2.5 miles from the pit, the road came to the crest of a small hill. The road then passed through three curves in a 0.43 mile stretch. The accident occurred as the truck operator entered the third curve in this section of the road.

2. The average width of this stretch of road ranged from 95 to 112 feet. From the crest of the small hill, the road passed through a right-hand curve with an inside radius of 490 feet and a 6% downhill grade. Immediately upon exiting this curve, the road made a left-hand curve with an inside radius of 463 feet. Through this zone, the downhill grade reduced to 3%. Upon exiting this curve, the road progressed into a slowly developing right-hand curve with an inside radius of 1407 feet. The grade further reduced to approximately 0.5% entering the last curve. The last curve was banked at a 3% grade toward the inside.

3. The berm that the truck impacted was approximately 275 feet long, 7.5 feet high, and between 25 and 30 feet wide at its base. The truck struck the berm 98 feet from the eastern end of the berm. The berm contained boulders and firmly packed sand and gravel material. Approximately 45 tons of material were displaced when the truck passed through the berm.

4. The minimum sight distance at the entrance to the last curve was approximately 1060 feet. Since the truck's normal stopping distance would be considerably less than this value, sight distance was not a factor in this accident. Furthermore, based on the combination of the radius of the curve, the banking provided, and the road surface condition, the banking forces generated by the loaded coal hauler traveling at 40 miles per hour (MPH) would not have exceeded the available frictional resistance. That is, the truck should not have skidded to the outside going through the curve. Skid marks were not present.

5. The truck involved in the accident was a Euclid CH-150 Coal Hauler, company identification No. 19-7115 (Unit #15). The net weight of the Euclid CH-150 coal hauler, which consisted of the tractor and trailer combination, was approximately 205,600 pounds. The gross vehicle weight of the coal hauler was approximately 505,600 pounds when loaded with 150 tons. The combined unit was comprised of a Euclid Model 311CH, bottom dump trailer, pulled by a Euclid Model 302 HDT tractor. The truck was approximately 79 feet long and 17 feet wide. Based on the manufacturer's information, the truck was rated for a load capacity of 150 tons, but due to the limited volume capacity of the trailer, it could only contain approximately 132 tons of raw coal. The truck was loaded at the time of the accident.

6. TRACTOR: The tractor for the coal hauler involved in the accident was a Euclid Model 302 HDT, Serial No. 69398. This tractor had a front steering axle and one axle in the rear. The front axle had one wheel on each side and the rear axle had dual wheels. The engine in the coal hauler was a Cummins Model KTA-2300-C1050 with 1050 hp. Records received from the manufacturer indicated this tractor was shipped from the manufacturer on May 17, 1979. The approximate weight of the tractor was 96,900 pounds.

7. TRAILER ASSEMBLY: The trailer for the coal hauler involved in the accident was a Euclid Model 311CH, Serial No. 69515. The trailer had one rear axle with dual wheels. The rear wheels of the tractor carried the weight of the front of the trailer. Records received from the manufacturer indicated this trailer was shipped from the manufacturer on May 22, 1979. The approximate weight of the trailer was 108,700 pounds.

8. STEERING: At the accident site, the tractor was found with the front steering wheels turned in the left direction. The engine was started and an attempt was made to steer the tractor. The tractor did not steer in either direction. When an attempt was made to turn the steering to the left, no movement occurred. Visual examination showed that the steering axle was in the extreme left turn position. When an attempt was made to turn the steering to the right, oil leaked from a hydraulic hose located under the operator's compartment. Visual examination showed that this hose was located between the steering valve located under the floor of the operator's compartment and the crossover relief valve, which was located on the front of the steering axle. The leaking hose was removed and replaced with an undamaged hose, and the steering was retested. With the replacement hose installed, the tractor steered in both directions.

9. STEERING HOSE: The leaking steering hose was visually examined. The hose was worn where it had been rubbing against the support member of the tractor frame, and a hole was found in the worn area. Prior to removal of the hose for inspection, it was strapped together with other hoses. The hose was not clamped in the area of the damage to prevent it from rubbing against the tractor frame.

    The damaged steering hose was an Aeroquip hose, part number 2781-16. This hose had a nominal inside diameter (ID) of one inch. Information from Aeroquip stated the working pressure for the hose was 2,500 psi, and the burst pressure was 8,000 psi. These hose pressure ratings agree with the machine manufacturer's recommended hose pressure ratings for the steering circuit.

    In addition to the part number, the damaged steering hose was identified by the number 3Q/79. According to information received from Aeroquip, this number identified the hose as being manufactured in the third quarter of 1979. The tractor was shipped from the manufacturer in the second quarter of 1979. This indicates that the steering hose, which had been damaged by rubbing the tractor frame, had been installed after the machine arrived at the mine.

10. STEERING CIRCUIT PRESSURE: The service manual for the coal hauler stated that the working pressure in the steering circuit should be 2500 psi. A check of the working pressure in the steering circuit revealed that it was 2450 psi. Both the working pressure recommended by the machine manufacturer and the actual measured working pressure in the steering circuit were within the hose manufacturer's recommended working pressure. The steering valve on the coal hauler is closed center, which means the hydraulic oil in the steering cylinders and in the hoses to the steering cylinders is trapped when the machine is not being steered. The steering circuit has a crossover relief valve which transfers pressure from one side of the steering cylinders to the other in the event of road shock. The maintenance manual for the coal hauler states the pressure setting on the crossover relief valve should be set at 3000 PSI. The 3000 PSI recommended setting for the crossover relief is slightly more than the 2500 PSI recommended working pressure of the steering hoses, but is well under the burst pressure of 8000 PSI.

11. SOIL SAMPLE TEST: In order to determine if the hose burst before or after the coal hauler hit the berm, soil samples were collected in the path that the coal hauler traveled before it hit the berm. Three of these samples (1A, 3A and 4A) were collected directly in the path of the truck. Another sample (2A) was collected from an area where the subject haul truck did not travel. These four soil samples, a sample (3C) of oil from the steering circuit hydraulic oil tank of the truck involved in the accident, and a sample (5A) of additive used in the dust suppression system were evaluated by an independent testing laboratory. A sample of oil, which was taken from the lube truck, was not sent to the lab. The testing showed that samples 1A and 3A, taken from the left side of the truck's path, contained oil that matched the oil taken from the steering circuit of the truck involved in the accident. The test of sample 4A, taken from the right side of the truck's path, showed that it contained oil based material, but it did not match the steering oil. The test of sample 2A, taken from the area where the subject haul truck did not travel, showed that this sample did not contain either the steering oil or the dust suppression additive. The tests of the three samples (1A, 3A, and 4A), that were taken from the travel path of the coal hauler, showed that no dust suppression additive was in the samples. The location and identification numbers of the soil samples are shown on the sketch on page 1. See Appendix D, page 21, for the laboratory report (not included in internet version).

12. Interviews with haul truck operators indicated that most operators travel between 30 and 40 MPH in the location of the accident. At these speeds the coal haulers travel between 44 and 58 feet each second. During the accident investigation, the tracks of the coal hauler involved in the accident were still visible in the haul road. Approximately 280 feet before the truck struck the berm, the right wheel traveled through a soft spot ("blow hole") in the road. As the truck left the soft spot, the tracks showed that it veered slightly to the right. The right turn in the haul road where the accident occurred began approximately 120 feet from the soft spot. Instead of turning right, the truck started veering slightly to the left and traveled until it hit the berm. The first soil sample (3A) that contained steering oil was collected approximately 40 feet beyond where the operator would have needed to start steering to the right. The second soil sample (1A) that contained steering oil was collected approximately 83 feet beyond the location where the first sample was taken. The oil at this location covered a much larger area than in any other location. At this point, the coal hauler was approximately 40 feet from the impact point on the berm. If the haul truck was traveling at the typical speed of 30 to 40 MPH, the machine would have traveled the 40 feet and impacted the berm in less than two seconds. The haul truck impacted the berm at a 55 to 70 degree angle.

13. The material in the "blow hole" near the accident site was of a dry, powdery consistency. The "blow hole" measured approximately 21 feet wide by 24 feet long. Located to the left of the road way centerline and in the path of loaded haul trucks, it was approximately 280 feet from where the truck went through the berm.

14. SERVICE BRAKE SYSTEM: The original service brake system installed on the coal hauler was an air over hydraulic system. At some point between the time the machine arrived at the mine and the time of the accident, the service brake system had been changed to an all hydraulic system. The service brake system had drum brakes on all six wheels. The brakes were applied in three different ways. The foot actuated brake valve applied the brakes on all three axles. There was also an auto apply system which applied the brakes on all three axles when the pressure in the steering circuit dropped to 1400 psi. This system kept the brakes applied until the pressure in the steering circuit reached 1800 psi. A third brake apply system, called the shovel brake, applied the brake on the trailer only.

    There were five hydraulic accumulators in the service brake system. The accumulators were charged with pressure from the steering circuit. The pressure for the brakes on each of the three axles was supplied from three individual accumulators for both the foot actuated and the automatic brake. The shovel brake was supplied from one of the other accumulators. The fifth accumulator was used to supply the pressure for the control part of the automatic brake.

15. SERVICE BRAKE TEST: The following tests of the service brake system were conducted:

    a. A force link was attached to the coal hauler, which still had most of the load it was hauling at the time of the accident. With the coal hauler running and the service brake applied, a crawler mounted dozer was used to apply a force of approximately 100,000 pounds to the coal hauler. The service brake kept the wheels on the coal hauler from turning while the dozer tracks spun.

    b. Tests were conducted to determine if automatic application of the service brakes would have occurred during the accident since there was a hole in one of the hoses in the steering circuit. The automatic control system for the service brakes applies the service brakes when pressure supplied to the steering circuit drops to 1400 psi. Since the hose with a hole in it was after the steering valve, the only time pressure would have been lost through the hose was when the steering wheel was being turned. When these tests were conducted, the old steering hose had been replaced with a new hose. To simulate a worst case scenario during the tests the new hose was totally disconnected at one end. With the hose disconnected, the steering wheel was turned to the right slow and fast with the engine at low idle and at full throttle. At full throttle, it took 20 seconds for the pressure in the steering circuit to drop to the point were the automatic service brake would have applied, when the steering wheel was turned to the right quickly. The pressure in the steering circuit did not drop when the engine was at full throttle and the steering wheel was turned to the right slowly. With the engine at low idle, it took 9 seconds for the pressure in the steering circuit to drop to the point were the automatic service brake would have applied when the steering wheel was being turned to the right quickly and 20 seconds when the steering wheel was being turned slowly. These tests indicated that it would have taken a minimum of at least nine seconds for the automatic service brake to activate. Considering the distance traveled and the approximate speed of the haul truck, it is unlikely that the automatic service brake applied before the truck hit the berm.

16. PARK BRAKE: The coal hauler had a level actuated shoe drum park brake which was mounted in the drive line. The force to apply the park brake was supplied by a spring inside of a hydraulic cylinder which was attached to the level on the park brake. To release the park brake, pressure was supplied to the hydraulic cylinder, which overcame the spring force.

    A pull test on the coal hauler with the park brake applied revealed the park brake was totally out of adjustment and would not hold the loaded coal hauler on the grades the coal hauler was being operated on at this mine. The grade that the coal hauler involved in the accident descended immediately prior to the accident had a maximum grade of 6 percent.

    A pull test on the coal hauler after the park brake was adjusted revealed the park brake would hold the fully loaded coal hauler on a 14 percent grade, which is a steeper grade than any of the grades the coal haulers operate at this mine.

17. RETARDER: The coal hauler had a hydraulic retarder as a part of the transmission to control the speed of the coal hauler while descending grades. The operation of the hydraulic retarder was tested in accordance with information obtained from the manufacturer, i.e., operate the engine at 2200 RPM, apply the hydraulic retarder, and engine speed should drop to approximately 1900 RPM. When tested, the hydraulic retarder was found to be operating within the manufacturer's test specifications.

18. The operator's seat in the truck was equipped with a shoulder harness type seat belt even though the truck was not provided with a Rollover Protective Structure (ROPS). Seat belts are not required to be worn in vehicles not equipped with ROPS.

19. An examination of the seat belt showed it to be fully functional and adjusted to fit a person of Butler's build. When tested, the seat belt latched and unlatched satisfactorily. None of the interviewees could state whether the victim was wearing his seat belt when last seen. Leadman, William Frost, had never reprimanded an employee for failure to wear a seat belt. All parties interviewed stated it was a condition of employment to wear a seat belt when operating mobile equipment. This was additionally stressed with decal stickers on the dashboards of all equipment, including the accident vehicle. They all said they wore their seatbelts at all times. It was apparent the victim was not wearing his seat belt when the truck struck the berm. However, it is not known if Butler had removed the seat belt and was attempting to exit the truck prior to the accident.

20. Truck drivers stated that 30 to 40 MPH was the maximum designed speed for the Model CH-150 haul trucks and the haul roads were maintained to safely operate these trucks at that speed. Left hand traffic was required on all haul roads and the posted speed limit was 40 MPH.

21. The mine was in an increased coal production mode to fill a temporary order due to a labor dispute at another mine in the region. This situation necessitated demands on employees of the Black Butte work force to be assigned to jobs outside their normal work duties. In addition, employees were asked to volunteer to work extra shifts and new employees were being hired. The truck drivers for the night shift on July 29, 2000, consisted of persons fitting all of these descriptions.

22. Butler had nine years, twenty-eight weeks mining experience and was normally assigned as a dragline dozer operator. He had not operated a Model CH-150, Euclid haul truck for several years with the exception of the following two most recent occasions. Company records indicated Butler had operated this type of haul truck for 1 hour on October 31, 1999, and for 11.5 hours on July 17, 2000. Butler completed 5 hours of task training for operating a Euclid CH-150 haul truck on July 18, 1991, and had operated this type of truck at the mine for approximately 4 years. He had received annual refresher training on December 7, 1999. Since Butler had completed task training on the Euclid truck, had operated it for 4 years previously, and had safely operated it within the preceding 12 months, no task training violation was found.

23. Tests of the steering and braking systems for the Euclid Unit #15 haul truck indicated that, other than the damaged hose, no defects were found that would contribute to the accident.

CONCLUSION


The direct cause of the accident was a ruptured hydraulic steering hose which caused Butler to loose steering control of the truck. Testing of the steering system showed that the truck would not steer to the right. Visual examination showed that the loss of steering was caused by loss of hydraulic pressure through a hole in a worn steering hose. The damaged steering hose was worn from rubbing against the frame of the coal hauler. This hose was not secured in the area of the damage to prevent it from rubbing the frame of the coal hauler. Soil samples tested for oil compatible with the steering oil from the truck indicated that the loss of steering oil occurred prior to the truck impacting the haul road berm. Contributing factors were the victim not wearing a seat belt; failure to stop the truck before impacting the berm; and the limited operating time of Butler on the Euclid truck in recent years.

ENFORCEMENT ACTION


1. A Section 103(k) Order (No. 7617887), dated July 30, 2000, was issued to the operator to ensure the safety of all persons until an investigation could be completed and the Pit No. 10 haul road deemed safe.

2. A Section 104(a) Citation (No. 7625876), dated December 11, 2000, was issued to the operator for a violation of 30 CFR §77.404(a). It was issued with "Moderate" Negligence and with Gravity as "Occurred," "Fatal," and "Significant and Substantial." The violation stated, "The mine operator failed to maintain the Euclid, Model CH-150, No. 19-7115 haul truck in a safe operating condition while being used to transport coal from Pit No. 10 on July 29, 2000. A one-inch, steel braided, hydraulic steering hose was allowed to contact the metal truck frame for an extended period of time. This caused the steel braids to wear and weaken to the point the hose ruptured under the system's pressure. The sudden failure of the hose disabled the steering and caused the truck to travel uncontrolled through a berm. The operator of the haul truck, not wearing a seat belt, received fatal injuries as a result of being ejected from the operator's compartment through the windshield. Soil samples, collected from an area within the truck's path prior to impacting the berm, were analyzed and contained oil consistent with that used in the truck's steering system."


Related Fatal Alert Bulletin:
FAB00C17

Sketch showing locations of soil samples taken.






APPENDIX A

List of persons participating in the investigation:

BLACK BUTTE COMPANY OFFICIALS
William Hill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mine Manager
Don Kollekowski . . . . . . . . . . . . . . . . . . . . . . . . . .Safety Supervisor
Howard Starr . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Planner Superintendent
Jim Vugrinec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maintenance Planner
PETER KIEWIT SON'S, INC.
Glenn Summers . . . . . . . . . . . . . . . . . . . . . . . . . . . Attorney
BLACK BUTTE COMPANY EMPLOYEES
Arron Smith . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mechanic
STATE OF WYOMING
Donald G. Stauffenberg . . . . . . . . . . . . . . . . . . . . . .State Inspector of Mines
Rudy King . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Deputy Mine Inspector
SWEETWATER COUNTY SHERIFF'S OFFICE
Marc Furman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Detective
MINE SAFETY AND HEALTH ADMINISTRATION
Michael F. Havrilla . . . . . . . . . . . . . . . . . . . . . . . . . Coal Mine Safety & Health Inspector
Dennis Tobin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Educational Field Services Specialist
William E. Vetter . . . . . . . . . . . . . . . . . . . . . . . . . . .Coal Mine Safety & Health Specialist
Eugene D. Hennen . . . . . . . . . . . . . . . . . . . . . . . . . .Mechanical Engineer, Technical Support
Darren J. Blank . . . . . . . . . . . . . . . . . . . . . . . . . . . . Civil Engineer, Technical Support


APPENDIX B

List of persons interviewed:

BLACK BUTTE COMPANY EMPLOYEES
Joshua Roberts . . . . . . . . . . . . . . . . . . . . . . . . . . .Truck Driver/Equipment Operator
Dewain Moore . . . . . . . . . . . . . . . . . . . . . . . . . . . Truck Driver
Paul L. Hiltner . . . . . . . . . . . . . . . . . . . . . . . . . . . .Truck Driver
Troy W. Householder . . . . . . . . . . . . . . . . . . . . . . Dragline Dozer Operator/Truck Driver
Kevin L. Eccles . . . . . . . . . . . . . . . . . . . . . . . . . . .Reclaim Dozer Operator/Truck Driver
Jerry D. Ray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Equipment Operator/Truck Driver
George Spence . . . . . . . . . . . . . . . . . . . . . . . . . . . Loader Operator
William A. Frost . . . . . . . . . . . . . . . . . . . . . . . . . . .Truck Driver/Leadman

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