DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
COAL MINE SAFETY AND HEALTH
REPORT OF INVESTIGATION
Surface Coal Mine
Fatal Powered Haulage Accident
April 26, 2002
Lee Ranch Coal Company Mine
Lee Ranch Coal Company
Grants, McKinley County, New Mexico
ID No. 29-01879
Coal Mine Safety and Health Inspector
James L. Angel
Anita L. Goodman
Mine Safety and Health Administration
P. O. Box 25367
Denver, Colorado 80225-0367
Allyn C. Davis, District Manager
Report Release Date: November 15, 2002
On Friday, April 26, 2002, at 9:30 p.m., Horace V. Bohannon, age 61, a welder/mechanic, was fatally injured after falling beneath a runaway Ford LT9000 series fuel/lube truck, company number U936. The accident occurred on a ramp at the end of the 6 West pit while Bohannon was fueling a D11R Caterpillar bulldozer, company number DZ157. The ramp sloped from 5.1 to 10.9 percent downgrade. Bohannon parked the fuel/lube truck near the top of the ramp on a 10.7 percent grade, facing downhill, and chocked two of the rear wheels. While fueling the bulldozer, Bohannon and Jason Knotts, bulldozer operator, walked toward the front of the bulldozer to check on a coolant problem. Bohannon said something and Knotts turned around to see the fuel/lube truck moving down the ramp. Bohannon ran after the truck and tried to enter the driver's side door. Knotts lost sight of Bohannon when the truck veered to the left. Bohannon fell beneath the truck and was struck by the rear wheels. Knotts used the radio on the bulldozer to summon help then ran to assist Bohannon. He checked for breathing and a pulse but found none. The mine's emergency response members arrived and within 20 minutes prepared Bohannon and transported him by mine ambulance to the Cibola General Hospital in Grants, New Mexico. The Life Flight helicopter was requested but was unavailable.
The direct cause of the accident was failure of the parking brakes to hold the fuel/lube truck on a pit ramp during refueling operations. The brake failure was caused by mechanical defects consisting of a non-functional brake chamber and worn brake slack adjusters causing excessive parking brake push rod travel. An additional cause was the improper placement of wheel chocks. The chocks were not placed squarely against the tires and were not placed against tires below the truck's center of gravity. The chocks were placed on rear axle tires and should have been placed on the downhill front axle tires. In addition, one of the chocks was placed on the uphill side of the tire, and thus did not resist downhill movement of the truck. Contributing factors to the accident were parking on a 10.7 percent grade when flatter areas were readily available; parking the vehicle facing downhill when room was available to park across the slope facing a bank or berm; and gear lube oil on the left rear tandem brake shoes, which reduced parking brake capability. The root causes of the accident were identified as insufficient training and a lack of procedures to ensure safe work practices.
The Lee Ranch Coal Company mine is a surface sub-bituminous coal mine located approximately 35 miles northwest of Grants, New Mexico, in McKinley County. The mine began operations in 1984. It is operated by Lee Ranch Coal Company, a Division of Peabody Natural Resources Company. Lee Ranch Coal Company is a partnership consisting of Peabody America, Inc. of St. Louis, Missouri, and Gold Fields Mining Corporation of Golden, Colorado.
Seven seams of sub-bituminous coal are mined in the San Juan formation. The seams are designated as UP, P, P1, Upper BA, Lower BA, Upper BB, and Lower BB. Seam thicknesses range from 1.5 to 8.5 feet. Partings between the seams vary from a few inches to 30 feet. The mine has 4 active pits. Overburden is removed by a Bucyrus Erie model 1570 dragline with an 87 cubic yard bucket; a Bucyrus Erie model 495 BII shovel with a 67 cubic yard bucket; and a Bucyrus Erie model 4100A shovel with a 64 cubic yard bucket.
Coal is loaded into haul trucks with Letourneau L-1100 front-end loaders and transported to a railroad loadout facility, where it is crushed to a 2-inch size or smaller. It is loaded onto rail cars for delivery to five southwestern electric power plants.
The mine works two 12-hour shifts per day, seven days per week. Production shifts start at 7:00 a.m. and 7:00 p.m. Maintenance shifts start at 6:30 a.m. and 6:30 p.m. The mine employs 288 persons and produced six million tons of coal in 2001.
The last Mine Safety and Health Administration (MSHA) regular safety and health (AAA) inspection was completed on October 31, 2001. The Non-fatal Days Lost (NFDL) incidence rate for the mine for calendar year 2001 was 1.99. The 2001 National incidence rate for the same period was 2.13.
The principal mine officials at the time of the accident were:
G. Brad Brown ......... Operations Manager
William A. Vance ......... Manager of Safety
Alfred Urioste ......... Preventative Maintenance Manager
James Nielsen ......... Maintenance Manager
Charles Marez ......... Acting Maintenance Supervisor
DESCRIPTION OF THE ACCIDENT
On Friday, April 26, 2002, the evening shift maintenance crew, supervised by Charles Marez, started work at 6:30 p.m.. Marez held a short meeting with the crew and assigned tasks for the shift. He did not give any special instructions other than to work safely and to report any safety concerns to him. Horace Bohannon, welder/mechanic and victim, was assigned to operate the fuel/lube truck. This was the third day of a 12-hour per day, 4-day work rotation for Bohannon. He conducted a pre-shift inspection of the truck and left the shop area. There was no indication that Bohannon found any safety problems or that he communicated any problems to anyone about the truck that shift.
During the shift, Jason Knotts, bulldozer operator, contacted Bohannon by radio to have his bulldozer refueled. Knotts continued his duties pushing overburden until he saw the fuel/lube truck parked near the top of the ramp at the end of the 6 West pit. He took his bulldozer to the fuel/lube truck to begin refueling. Knotts parked the bulldozer behind and to the side of the truck, facing up the ramp. The truck was parked facing down the ramp. When Knotts got off the bulldozer, he saw Bohannon get out of the fuel/lube truck and place chocks against the rear wheels. Refueling, using a Wiggins automatic shutoff system, was started at approximately 9:30 p.m. During refueling, the two men walked toward the front of the bulldozer to check on a coolant problem. Knotts heard Bohannon say something and turned around to see him running after the fuel/lube truck, which was moving down the ramp. The truck continued down the ramp and veered slightly to the left. As the truck went to the left, Knotts momentarily lost sight of Bohannon, who was trying to enter the truck on the driver's side. He next saw Bohannon on the ground near the rear of the truck. The fuel/lube truck hit the front of a parked 240-ton Liebherr haul truck and came to a stop. Knotts knew a serious accident had occurred. He got back on the bulldozer and used the radio to summon help. Knotts then went to assist Bohannon.
Bruce Fuell, production foreman, was in the area to move a light plant. He heard the emergency call and went to assist. Fuell and Knotts checked Bohannon for vital signs, but found none. Wilford Olguin, a first responder, also heard the emergency call and went to get the company ambulance. Bohannon was placed in the ambulance and transported to the Cibola General Hospital in Grants, New Mexico, where he was pronounced dead by Dr. Robert Kilgo.
INVESTIGATION OF THE ACCIDENT
Gene Ray, acting MSHA field office supervisor at Aztec, New Mexico, was notified of the accident shortly after 9:30 p.m., April 26, 2002. He advised the company to secure and make the area safe and initiated MSHA accident investigation procedures. Jeff D. Scott, MSHA Coal Mine Safety and Health inspector, Aztec, New Mexico Field Office, arrived at the site on April 27, 2002, at 11:25 a.m. He issued a Section 103(k) order to assure the safety of persons at the mine until an investigation could be conducted and the area deemed safe.
Lester Coleman, Coal Mine Safety and Health inspector from Castle Dale, Utah, was assigned as the lead investigator. Other MSHA investigators were James Angel, mechanical engineer, Technical Support, Triadelphia, West Virginia, and Anita Goodman, training specialist, Educational Field Services, Delta, Colorado.
The MSHA accident investigation team arrived at the mine on April 28, 2002, to start the investigation. Interviews were conducted with witnesses and the accident site was examined. The fuel/lube truck was examined and tested. The investigative work at the mine concluded on April 30, 2002.
1. MACHINE INFORMATION: The Ford Model LT9000 was an on-highway truck that was converted into an off-road fuel/lube vehicle with the addition of a prefabricated fuel/lube body provided by the Maintainer Company. The truck was approximately 31 feet long, 8 feet wide, and 10 feet high. It had two rear axles each with dual wheels. Mine operator specifications listed the truck's gross vehicle weight rating as 64,000 pounds. The weight of the truck at the time of the accident was estimated as 48,000 pounds. The truck was powered by a Cummins Model L-10 engine. It was a 1995 model year manufactured in June 1994.
2. The fuel/lube system on the truck consisted of a 1500 gallon diesel fuel tank, one 50 gallon oil tank, seven 175 gallon tanks with various oils and antifreeze, one 220 gallon oil tank, and a gasoline powered air compressor. Hose reels for each of the tanks were located at the back of the truck. The refueling system was a Wiggins automatic shutoff system. After the accident, the fuel nozzle was found attached to the dozer. The hose had broken where it connected to the nozzle. The fuel hose reel had completely unwound and fuel from the broken hose drained to the ground following the path of the truck.
3. OPERATOR'S COMPARTMENT: The odometer showed 52,812 miles. The start button key switch was found in the "ON" position. The transmission was automatic with five forward gears and one reverse. The transmission gear selection lever was found in the neutral position. The differential wheel lock was found in the unlocked position. The parking brake control valve was found in the "out" or brake applied position. Note that this brake valve automatically moves to the out position and applies the parking brakes with loss of brake system air pressure. No air pressure was present in the brake system when it was inspected after the accident. When the control was pushed in, it returned to the out position. The control appeared to operate properly.
The dashboard and steering wheel were pushed backed to the driver's seat. The engine was pushed back about 22 inches. The engine had entered the operator's compartment and severely deformed the firewall and floor. The accelerator, brake pedals, and the transmission lever were pushed out of position due to damage to the operator's compartment.
4. BRAKE SYSTEM DESCRIPTION AND INSPECTION: The service brake system consisted of air pressure actuators that applied shoe and drum "S-cam" type brakes at the wheels. The parking brake system consisted of spring applied, air pressure released actuators mounted to the service brake actuators on the rear wheels. Automatic slack adjusters installed at each wheel were designed to maintain proper shoe to drum clearance. The service brakes were applied using a brake foot pedal. The parking brake was applied by pulling an actuator valve mounted on the dashboard. Pushing this valve in released the parking brakes. Air pressure of 90-125 psi for the braking systems was generated by a compressor which was gear driven by the engine. If the air pressure fell below 35-45 psi, the parking brake actuator automatically applied the parking brakes.
The brake systems were inspected after the accident. Prior to any disassembly, the truck was pushed with another vehicle. No air pressure was present to release the parking brake. All of the rear wheels rolled. This test was performed on loose gravel. It indicated that insufficient braking force was being developed by the parking brake system to skid/hold the wheels.
Several air hose defects were observed. The air supply line to the quick release valve for the rear tandem axle parking brake chambers and the air supply line to the left rear tandem service brake chamber were severely frayed, exposing the wire braid in the hoses. These hoses did not leak when air pressure was applied. Also, the air supply line at the right front tandem axle's service brake chamber was severely kinked. Finally, the hose (to the right front tandem parking brake) fitting at the quick release valve was loose. When the hose was moved by hand, air could be heard escaping at the fitting. None of these defects were considered by the investigators to have contributed to the accident.
5. New brake shoes had been installed on all four rear brakes according to mine operator's maintenance records on April 16, 2002. When inspected, the brake shoes looked new and were properly installed. The only defect noted with the brake shoes was the presence of gear lube oil on all four brake pads of the left rear tandem brake unit. The gear lube was leaking from the axle's wheel seal. A heavy layer of lube oil and dirt, extended approximately 1-1/2 to 3 inches from the outer edge of the brake pads toward the center of the vehicle. This defect would have greatly reduced the parking brake holding ability of this wheel at the time of the accident. Information provided by the operator indicated that this oil leak was not present when the brakes were changed on April 16, 2002. The company further stated that there was no visible indication of this leak at the time of the accident investigation. It was only found after the tires and brake drums were removed during the investigation. This leak would not have been visible during the equipment operator's pre-shift inspections.
6. The push rod stroke of all brake units was measured by applying 100 psi shop air to the brake chambers. The front brakes use type 20 chambers with a maximum travel before adjustment of 1-3/4 inches. Measurements obtained were:
Front Left: measured 1-1/8 inches
Front Right: measured 1-11/32 inches
The front brakes had acceptable stroke lengths.
The rear brakes use type 24, long stroke chambers with a maximum travel before adjustment of 2 inches. These chambers have a maximum stroke of 2-1/2 inches. The stroke of both the service brake chamber and parking brake chamber were measured as follows:
Left Front TandemThe right rear tandem parking and service brake chambers were tested with the chamber removed from the vehicle. The test demonstrated that a failure inside the chamber prevented any significant movement of the push rod, causing a defect.
Parking Brake: 2-3/8 inches - DEFECTIVE
Service Brake: 2-1/2 inches - DEFECTIVE
Left Rear Tandem
Parking Brake: 1-9/16 inches - ACCEPTABLE
Service Brake: 1-23/32 inches - ACCEPTABLE
Right Front Tandem
Parking Brake: 2-5/32 inches - DEFECTIVE
Service Brake: 2-1/4 inches - DEFECTIVE
Right Rear Tandem
Parking Brake: 3/16 inches - DEFECTIVE
Service Brake: 1/4 inches - DEFECTIVE
The left and right front tandem brakes were defective in that their strokes exceeded the maximum 2" stroke limit for these type chambers. Further, the brake chamber on the right rear tandem was non-functional, as described above. Only the stroke of the left rear tandem chamber's push rod was within the acceptable range. However, as noted above, this was the brake unit that had grease on the linings. These defects would have greatly reduced the parking brake's holding ability at the time of the accident.
7. The slack adjusters on the right and left front tandem were tested in accordance with the slack adjuster pinpoint test specified in Ford's maintenance manual for the LT9000 page 06-08D-3. Neither slack adjuster appeared to operate properly. Repeated operation (17 times) of the brake using shop air supplied to the chamber did not reduce the push rod travel to less than approximately 2-1/2". These slack adjusters were considered defective. Their failure resulted in the excessive push rod travel noted above. The slack adjusters on the rear tandem could not be tested because of working difficulties following the Ford procedure (e.g. stuck hex nut, difficulty in gaining access to slack adjuster).
8. CHOCKS: Two chocks, manufactured by Checkers Industrial Products, Inc. (Checkers), were found at the accident site. The chocks, Checkers Model UC1500-4.5, were constructed of orange urethane, triangular in shape, and connect by a rope. The base of the chocks was 11 by 7-3/4 inches, and they had a chevron pattern molded into them. The chocks were 8 inches high. The front of the chocks, the slightly curved surface that fits against the tire, had raised bars across the surface.
The chocks were located in the tire track made by the left outside tandem wheels (driver's side of truck). The uphill chock was laying on its back side which gave the appearance that it had rolled backward as the tire went over it. The downhill chock apparently did not move as the tire ran over it from back to front. A clear impression of this chock's base chevron pattern was present on the ground beneath the chock when it was lifted. Ripples in the sides of the chock gave the appearance that the chock had been crushed. Checkers stated that this is the pattern seen when a chock is crushed.
The company stated that urethane-type wheel chocks have been used at the mine since it went into production in November 1984. According to the company, no other incidents/accidents involving this type of chock have occurred.
9. The ramp surface material was a soft sandstone with mostly hard packed dirt and rocks of various sizes. The surface of the ramp where the chocks were located was firm. There was no indication that the chocks had sunk into the ground to any significant extent. The ramp surface may have been slightly wet from water truck spray to control dust at the time of the accident. The ramp sloped down at a 10.7 percent grade where the truck was parked.
10. During the investigation, the uphill chock was placed into what was considered its position prior to it rolling backwards as the wheel ran over it. The impressions in the ramp surface were used to do this. The downhill chock was already in what was considered its position prior to the accident. The investigation indicated that the chocks had been placed against tires on the left side of the truck on the two rear tandem axles. One had apparently been placed on the uphill side of the outer left front axle tire and one had been place on the downhill side of the outer left rear axle tire. In these positions, only one of the two chocks was placed on the downhill side of the tire and offered resistance to initial downhill movement.
It also appeared that the chocks had not been placed squarely against the tires. The backs of the chocks were 2-3 inches closer to the outside of the tire track than the front of the chocks. The outside distance between the chocks was approximately 36-1/2 inches. This is approximately the inside dimension of the rear tandem tires where they began to contact the ground. The tires were Hankook steel belted radials, size 11R22.5.
11. Information on proper placement of the chocks was provided by Checkers in an April 29, 2002, letter to MSHA with attached "Wheel Chock User Guidelines." Checkers' letter states that chocks must be used in pairs and positioned downhill and below the truck's center of gravity. For trucks disabled while traveling downhill or parked facing downhill (as in this accident), the front wheels would need chocked. Chocks must also be positioned snugly and squarely against the center of the tire treads. Checkers stated that many mines do not expect wheel chocks to securely hold a loaded truck on a steep grade and generally recommend turning the wheels into a berm and using wheel chocks where possible. In addition, Checkers stated that the UC1500-4.5 chock is a light weight "over the road" chock, and that, "a variety of chocks should have been tested to determine the best chock for this particular application."
The position of the chocks indicated that they were not properly installed. An actual test was not conducted to determine if the chocks, as installed, would hold the truck on the grade. This test was not done due to safety considerations, the extensive damage to the truck, and the time and logistics that it would have taken to conduct the test.
12. The pre-shift inspection checklist for the fuel/lube truck for the day shift, prior to the accident, recorded only that the water, temperature, fuel guage and wiper blade needed attention. Parking brakes were checked as "OK." Bohannon's previous inspection checklist for the fuel/lube truck on April 24, 2002, night shift, recorded the parking brakes as "OK."
13. Refueling is performed on all shifts on different types of equipment and on different grades. The mine operator does not have a written policy pertaining to parking on inclines and chocking wheels.
14. TRAINING: A review of records and information provided by the company indicated that Bohannon had received the required Part 48 training, including task training on the fuel/lube truck. Bohannon was considered an experienced operator on this truck and provided task training on it to new operators. Regarding use of chocks, the company stated that chocking of vehicles was taught in new miner, refresher, and task training and was covered in the company's Health and Safety Handbook.
15. The fuel/lube truck traveled approximately 220 feet down the ramp and stopped after hitting head-on a parked 240-ton Liebherr haul truck. Bohannon was found approximately 165 feet down the ramp from where the fuel/lube truck was parked.
ROOT CAUSE ANALYSIS
A root cause analysis was performed on the accident. The following causal factors and root causes were identified:
1. Causal Factors - The fuel/lube truck was parked facing downhill on a 10.7 percent grade during refueling operations. Root Cause - The ramp was wide enough that the fuel/lube truck could have safely been parked across the grade instead of facing downhill. This would have prevented a runaway down the grade. At most, the truck would have drifted a short distance forward or backward into the spoil or berm on either side of the ramp. In addition, the 10.7 percent grade was one of the steepest grades on the ramp. Lesser grades were readily available. The parking location was not dictated by conditions or haste, as Bohannon selected the location and waited on the bulldozer to arrive. Insufficient training in recognizing a potentially hazardous parking situation and a lack of safe work procedures to address this work practice were identified as root causes.
2. Causal Factors - Two chocks were used to block the fuel/lube truck tires, but were not installed squarely against the tires, nor properly below the vehicle's center of gravity. Root Cause - The investigation found that two tires on the rear axles were chocked. One chock was placed on the downhill side of a tire and one on the uphill side. The uphill side chock did not provide any protection against initial downhill movement. Neither was placed squarely against the tire. In addition, proper placement required the chocks to be installed on tires downhill from the truck's center of gravity, i.e. on the front axle tires. Insufficient training and administrative procedures in the proper use and installation of chocks were root causes in this accident.
3. Causal Factors - Mechanical brake defects resulted in greatly reduced parking brake capabilities. These defects included a non-functional brake chamber and worn brake slack adjusters causing excessive parking brake push rod travel. Root Causes - The brake shoes on the rear axle wheels were replaced on April 16, 2002, ten days before the accident. The mechanical brake defects were not found/corrected at that time. The root cause for this oversight was insufficient training or a lack of procedures requiring brake adjustment checks when brake shoes are replaced. In addition, pre-operational inspections by equipment operators did not discover the brake defects. The "Daily Equipment Inspection" checklist requires parking brakes to be checked. Insufficient pre-operation inspection procedures ensuring a thorough quality control inspection were identified as root causes.
4. Causal Factor - Gear lube oil on the left rear tandem brake shoes reduced braking capability of that wheel. The leaking oil was not visible from the outside of the wheel unit and was only found when the tire and drums were removed. This defect was not observed during the April 16, 2002, brake repairs. Improved quality control pre-operational inspections could help discover this problem.
The direct cause of the accident was failure of the parking brakes to hold the fuel/lube truck on a pit ramp during refueling operations. The brake failure was caused by mechanical defects consisting of a non-functional brake chamber and worn brake slack adjusters causing excessive parking brake push rod travel. An additional cause was the improper placement of wheel chocks. The chocks were not placed squarely against the tires and were not placed against tires below the truck's center of gravity. The chocks were placed on rear axle tires and should have been placed on the downhill front axle tires. In addition, one of the chocks was placed on the uphill side of the tire, and thus did not resist downhill movement of the truck. Contributing factors to the accident were parking on a 10.7 percent grade when flatter areas were readily available; parking facing downhill when room was available to park across the slope facing a bank or berm; and gear lube oil on the left rear tandem brake shoes, which reduced parking brake capability. The root causes of the accident were identified as insufficient training and a lack of procedures to ensure safe work practices.
A Section 103(k) Order No. 7604653 was issued on April 27, 2002, to ensure the safety of all persons until an investigation could be completed and the area deemed safe.
A Section 104(a) Citation No. 7635152 was issued on November 20, 2002, for a violation of 30 CFR 77.1605(b) for not maintaining the parking brakes on the fuel/lube truck in a functional condition. The "Condition or Practice" states, "The parking brakes on the Ford LT9000 fuel/lube truck, company number U936, were not maintained in a functional condition. Gear lube oil was present on all four brake shoes of the left rear tandem brake unit. The left and right front tandem parking brakes were defective in that excessive wear of the slack adjusters allowed the push rod strokes to exceed the maximum 2.0-inch stroke limit for these type chambers. The right rear tandem brake chamber would not function. These defects greatly reduced the holding ability of the parking brakes and were a direct cause of the fatal haulage accident that occurred on April 26, 2002."
A Section 104(a) Citation No. 7635153 was issued on November 20, 2002, for a violation of 30 CFR 77.1607(n) for not properly blocking the wheels of the fuel/lube truck while parked on a slope. The "Condition or Practice" states, "The Ford LT9000 fuel/lube truck, company number U936, was parked on a grade of 10.7 percent. The vehicle was left unattended. The wheels were not turned into a bank or berm and were not properly blocked to prevent movement of the vehicle. This violation contributed to the cause of a fatal haulage accident on April 26, 2002."
Related Fatal Alert Bulletin:
Persons furnishing information and/or present during the investigation were as follows:
LEE RANCH COAL COMPANY OFFICIALS
G. Brad Brown .............. Operations ManagerLEE RANCH COAL COMPANY EMPLOYEES
William A. Vance .............. Manager of Safety
William Jarrell .............. Assistanty Safety Manager
Alfred Urioste .............. Preventative Maintenance Manager
James Nielsen .............. Maintenance Manager
Charles Marez .............. Acting Maintenance Supervisor
Jason Knotts .............. Dozer OperatorJACKSON & KELLY PLLC, ATTORNEYS AT LAW
William "Punk" Culver .............. Truck Driver
Soloman Molena .............. Fuel/Lube Truck Driver
(Representing Lee Ranch Coal Company)
Karen Johnston .............. AttorneyMINE SAFETY AND HEALTH ADMINISTRATION
Lester Coleman .............. Coal Mine Safety & Health Inspector, Lead Investigator
Anita L. Goodman .............. Training Specialist, Educational Field Services
James L. Angel .............. Mechanical Engineer, Technical Support
Jeff D. Scott .............. Coal Mine Safety & Health Inspector
APPENDIX BPersons interviewed during the investigation were as follows: LEE RANCH COAL COMPANY OFFICIAL
Charles Marez .............. Acting Maintenance SupervisorLEE RANCH COAL COMPANY EMPLOYEES
Jason Knotts .............. Dozer Operator
Solomon Molena .............. Fuel/Lube Truck Driver
William Culver .............. Truck Driver