DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
Metal and Nonmetal Mine Safety and Health
REPORT OF INVESTIGATION
Surface Nonmetal Mine
(Crushed Stone)
Fatal Machinery Accident
September 10, 2002
G. Edgar Harr Son's Corp. (H4C)
Cockeysville, Baltimore County, Maryland
at
Frederick Quarry, Redland Genstar Inc.
Frederick, Frederick County, Maryland
I.D. No. 18-00013
Accident Investigators
Kenneth A. Amati
Mine Safety and Health Inspector
Donald L. Ratliff
Mine Safety and Health Inspector
F. Terry Marshall
Mechanical Engineer
Darren J. Blank
Civil Engineer
Cynthia S. Shumiloff
Mine Safety and Health Specialist
Originating Office
Mine Safety and Health Administration
Northeast District
547 Keystone Drive, Suite 400
Warrendale, PA 15086-7573
James R. Petrie, District Manager
OVERVIEW
On September 10, 2002, Claude R. Cox, contract driller, age 58, was fatally injured when the drill rig he was operating overturned. The drill rig was positioned to drill cap rock and overburden material in the quarry.
There was no conclusive evidence to determine the cause of the accident. The right rear jack may have been raised in a sequence such that it was raised higher or faster than the left rear jack. Based on the final extensions of the jacks, the drill operator may have attempted to compensate the position of the right rear jack after the rig began to tip. This scenario by itself, or in conjunction with the right jack knuckle dropping into the jack pad collar could have caused the drill to become unstable and overturn.
Cox had a total of 25 years drilling experience, 12 at this mine. He had received training in accordance with 30 CFR, Part 46 on April 24, 2002.
Frederick Quarry, a crushed stone operation, owned and operated by Redland Genstar Inc., was located in Frederick, Frederick County, Maryland. The principal operating official was Patrick Reilly, plant manager. The mine normally operated three, 8-hour shifts per day, 5 days per week. Total employment was 47 persons.
Limestone was mined from multiple benches. The limestone was drilled, blasted, and hauled to the primary crusher by truck. The crushed limestone was conveyed to the various plants for secondary crushing and screening into a finished aggregate product that was sold for industrial use.
G. Edgar Harr Son's Corp., a contractor drilling company, located in Cockeysville, Baltimore County, Maryland, was contracted to drill holes for blasting as part of the mining process. The principal operating official was Paul M. Fabiszak, president. The contractor typically had two employees on site working 9 hours per day, 5-6 days a week.
The last regular inspection at this operation was completed on August 1, 2002.
On September 10, 2002, Claude R. Cox (victim) reported for work at 6:00 a.m., his normal starting time. At 7:00 a.m. Eugene Fritz, powderman, instructed Cox to re-drill a blocked hole that was located on the 9 bench south. Cox re-drilled the hole and changed the hammer size from 6 1/8 inch to 5 inch, in preparation to drill at the 1 bench south. At approximately 9:00 a.m., Larry Miller, pit supervisor, examined the 1 bench south drill site with Cox and found no problems. They decided the angle holes would be drilled at 15 degrees to a depth of 18 feet; the vertical holes would be drilled to a depth of 15 feet; and the spacing would be 10 feet. Miller then drove Cox to the 9 bench south to get his drill rig. Cox drove the drill rig to 1 bench south where he drilled without incident. At about 12:45 p.m., Fritz and Cox drove to 2 bench south to examine the next site to be drilled. Fritz returned Cox to his drill at 1:00 p.m. and left the area. At 1:30 p.m., Fritz returned to the 1 bench south and found the drill rig laying on its side. Miller heard Fritz call for help on the C.B. radio, and instructed the office staff to summon emergency personnel. When Miller arrived at the accident scene, he and Fritz both called out to Cox but did not receive a response. They found that they could not provide assistance to Cox who was trapped inside the drill station cab. Local paramedics arrived, and Cox was pronounced dead at the scene. Death was attributed to multiple injuries and compressional asphyxia.
MSHA was notified at 1:49 p.m. on the day of the accident by a telephone call from Joseph N. Ayers, safety manager, to Donald J. Foster, assistant district manager. An investigation was started the same day. An order was issued under the provisions of Section 103(k) of the Mine Act to ensure the safety of miners. MSHA's accident investigation team traveled to the mine; conducted a physical inspection of the accident site and equipment involved in the accident; interviewed a number of employees; and reviewed training records, conditions, and work procedures relevant to the accident. MSHA conducted the investigation with the assistance of mine management, contractor management, and the miners.
The accident occurred at the 1 bench south drill site. Prior to the accident, 12 toe holes had been drilled. In drilling the previous holes, the drill operator set up on the west and south sides of the spoil bank. The ground conditions for the previous holes were examined. The holes were 5 inches in diameter, between 12 and 20 feet deep, and drilled at angles that varied from 0 to 35 degrees.
At the time of the accident, the drill rig was positioned to drill the thirteenth hole into the cap rock and overburden material on the top of the pit located at the south end of the quarry. This formation of rock mixed with sandy soil had previously been blasted, but intact rock still remained near its base. This waste material was being removed to level the area in preparation for production shooting. The drill had been positioned nearly perpendicular to the base of the overburden formation on level ground at a bearing of approximately N30� E. The face of the overburden formation to be drilled was sloped at an angle of approximately 40 degrees. Weather conditions were clear and warm with no wind.
The rubber-tired drill was an Ingersoll-Rand T4BH, Serial Number 7346, equipped with a Cummins QSK19-C Deck Engine rated for 600 HP at 2,100 RPM and an air compressor rated for 1050 CFM at 350 PSIG. The drill was mounted on a three-axle, 6 X 4, CCC carrier, VIN 1CYDCL487VT043278, equipped with a 300 HP Cummins L-10 engine and a 10-speed Fuller RTO-11708LL transmission with 10 forward and 3 reverse speeds.
The length of the drill rig was 34 feet 6 inches with the tower down and 31 feet 9 inches with the tower up. The overall width was 8 feet 6 inches, with the height of 13 feet 11 inches with the tower down and 36 feet 8 inches with the tower up. The working weight was approximately 58,000 pounds. The tower had an overall length of 33 feet 3 inches. The drilling package allowed the tower to be positioned to a maximum angle of 20� from the vertical in increments of 5�. An angle drill tie bar, or "banana bar," was used to secure the mast at 5�, 10�, 15�, or 20�. A hydraulic cylinder was used to insert a pin in the "banana bar" to lock the mast at the desired angle, which was a remote pinning feature. The clearance of the tower's table, with respect to the contoured ground (embankment) behind the drill carrier, was examined and it was determined the table did not strike the ground. The tower angle of the machine prior to overturning was estimated to be approximately 25� (reference to a vertical position).
All controls for positioning, including the remote pinning feature, were located at the operator's console inside the drill station cab. The drill station cab was located on the right rear corner of the carrier and was oriented such that the drill operator faced the front of the carrier. The drill did not have the remote propel option, that provided tramming capabilities from within the drilling station cab.
The carrier was equipped with three, hydraulic operated, leveling jacks having a 5-inch diameter bore, 48-inch stroke, 4-inch diameter rod, each with a lifting capacity of 58,900 pounds. Each leveling jack was equipped with a counterbalance valve, and an 18-inch diameter jack foot.
One leveling jack was center mounted on the front bumper of the carrier, with the other two leveling jacks mounted on the rear corners of the carrier. The rear jack centers were spaced 7 feet apart. The distance from the front jack to rear jack centers measured 27 feet along the longitudinal axis of the carrier. The leveling system included a bubble in the enclosed drill station and a separate self-centering hand control for each of the three leveling jacks. The leveling bubble was visibly observed to be intact and functioning during the field investigation.
After the machine was uprighted, the front leveling jack cylinder was extended 39 1/8 inches, the right rear leveling jack cylinder 36 � inches, and the left rear leveling jack cylinder 34 � inches. Based on the extended positions of the leveling jack cylinders and the ground conditions, it was estimated that the right rear corner of the carrier would have been approximately 4 to 5 inches higher than the left rear corner of the machine. It was estimated that the carrier was relatively level from front to rear. Tire to ground clearances for the carrier were measured with the leveling jacks in these positions. The ground clearance for the left front steering tire was approximately 14 inches and the left rear tire clearances were an average of 20 � inches. The ground clearance for the right front steering tire was approximately 11 � inches and the right rear tire clearances were an average of 24 inches.
When tested, the counterbalance valves of the three leveling jacks did not reveal any leaks and functioned properly. The front leveling jack cylinder and the right rear leveling jack cylinder retracted approximately �-inch when the machine weight was left on the leveling jacks overnight and the tower placed in the down position.
All three jack feet were originally equipped with a pinned connection. This connection used a 1-inch diameter pin with cotter pins inserted through both ends to secure it to both the cylinder rod and jack foot pivot connection. The sockets in the jack feet were cupped and the cylinder rod ends were convex to provide a ball and socket joint which rotates around the pin's centerline. An engineering drawing provided by Ingersoll-Rand indicated that the jack foot socket depth was 2 � inches. By design, the jack feet had a 1 1/8-inch diameter hole on each side where the connection pin was inserted. The rod end had a nominal 1 1/8-inch diameter hole for the pin that was countersunk on each side providing a 10� taper. This allowed the pin to pivot slightly with respect to the cylinder rod end, providing additional degrees of freedom to the pinned connection.
The drill had the original equipment manufacturer's type connection on the leveling jack mounted to the front of the carrier but did not have them in the two leveling jacks on the rear of the carrier. The two rear jack feet were connected by bolts in lieu of pins. The bolts were smaller in diameter than the OEM pins and extended well beyond the connection. The right rear foot used a 7/8-inch diameter bolt, 7 inches in length, and had a nut secured approximately flush with the threaded end. The bolt could move lengthwise an estimated 3 to 3 � inches through the connection when the jack pad was raised off the ground. The left rear foot used a 1-inch diameter bolt, 7 inches in length, but did not have a nut on the threaded end. It could not move lengthwise through the connection when the jack pad was off of the ground due to the bolt being distorted (bent) causing an interference type fit at the connection.
On each of the rear jacks, one of the two holes in the jack feet were damaged in that the bolts had torn through the cylindrical socket. The condition of the pinned connection of the right rear leveling jack allowed the ball and socket to separate when the jack foot was off the ground. During tests, the ball and socket could be oriented where the ball would ride on the edge of the jack foot socket while the machine was being leveled. A 1 � to 2-inch drop was observed when the ball slipped into the socket during subsequent machine movement.
Information regarding the center of gravity (COG) for a similar machine was provided by an Ingersoll-Rand representative. An evaluation of this information identified the following: The lateral location of the COG would be approximately a 2-to-1 ratio to that of the vertical difference between the right and left rear corners of the carrier. A 2-inch drop in the right rear would have caused the COG to move approximately 4 inches laterally. The lateral movement of the COG necessary for the machine to become unstable in a static condition with the tower at 30� would be at least 22 inches. This indicates that the differences between the left and right corners of the carrier would need to be at least 11 inches to cause the machine to become unstable in a static condition with the tower at 30�. In other words, the right rear corner would need to be 11 inches lower than the left rear corner for the machine to become unstable in a static position under these conditions. However, based on the ground heights at the estimated machine location immediately prior to the accident and the observed extended positions of the leveling jacks, the machine would actually have been leaning in the opposite direction with the left rear corner being 4 to 5 inches lower than the right rear corner.
Cribbing was not being used under any of the three jack feet to reduce the ground pressure. However, the physical evidence did not indicate that any of the leveling jacks sunk into the ground or significantly slid on the ground surface.
The filters for the hydraulic system were removed and visually inspected. No significant debris or dirt was observed within these filter elements. The relief pressure for the 9-spool hydraulic valve bank was tested to be approximately 2,800 PSI. The engineering drawing in the service manual provided with this machine stated that the relief pressure is set at 3,000 PSI. This 9-spool valve had nine hand control levers that controlled the carousel swing, the rotation, the rod wrench cylinder, the mast raise/lower, the three leveling jacks, the rod index cylinder, and the water injection motor. The rotation motor and the water injection motor were equipped with detent type hand controls while the remaining seven had spring-centered type hand controls. The drill station's operator panel also had detent type hand controls for the drill head rotation, the drill head feed, and the "banana bar locking pin." The drill head controls were found in the neutralized position and the throttle switch in the "run" position.
The tower cylinders and hand control (mast raise/lower) were tested with the tower removed from the machine. The cylinders were extended and retracted using the spring centered hand control lever on the 9-spool valve. Internal leakage of approximately 200 PSI/minute was detected with the cylinder fully extended and the hand control lever centered. This indicates that the tower would drift towards a horizontal position after the hand control lever was centered if the tower was angled at, or over, approximately 5�. The tower's locking pin (banana bar locking pin) was functional and hydraulic tests did not indicate any internal leakage that would have affected the pin position selected by the operator. The pin position indicator light did not function. The electrical circuit for this function was tested and the bulb was determined to be inoperative. The position indicator functioned after the bulb was replaced. The red indicator light was activated with the pin in the unlocked position and deactivated when the pin was moved to the locked position.
The tower was equipped with removable bushings at the pivot connections. After the tower was removed, wear in the bushings was quantified. Approximately 0.025 inches of total play was measured at the outboard side of both the left and right tower pin bushings.
The deck engine for the drill rig was reportedly not running when the first person arrived on the scene following the accident. The Cummins QSK deck engine had an electronic engine control with diagnostic storage capabilities. A Cummins' technician accessed this information when the machine was taken to an Ingersoll-Rand dealership in Lewisberry, Pennsylvania. The information indicated that the Engine Protection feature of the deck engine shut itself down due to a low oil pressure condition and that the engine was running at approximately 1,800 RPM when it detected this condition. This confirmed that the engine switch setting on the drill station control panel, observed during the field investigation, was representative of post accident conditions. No other engine fault codes were identified to exist during the time of the accident.
There were no defects detected within the hydraulic system or its controls that could have compromised the ability of the drill operator to control the leveling or the mast raise/lower functions of the machine.
The cause of the accident could not be determined. A defect in the right rear leveling jack assembly could have allowed the piston rod to suddenly drop approximately 1 � to 2 inches in the vertical direction at some point during or after the machine had been raised on its leveling jacks. However, based on the observed extended positions of the leveling jacks and the ground factors of the accident area, the defect found in the right rear leveling jack assembly could not, in and of itself, have allowed the machine to tip over. The drill operator may have raised the right rear jack in a sequence such that it was raised higher or faster than the left rear jack. Based on the final extensions of the jacks, the drill operator may have attempted to compensate the position of the right rear jack as the rig began to tip. This scenario by itself, or in conjunction with the right jack knuckle dropping into the jack pad collar, is one potential cause of the accident. There were no eyewitnesses to confirm the events that immediately preceded the accident.
The estimated orientation of the machine using the parameters found after the accident and the calculations of the static tip over conditions were examined. They suggested that either the drill operator had attempted to compensate the leveling jacks as the machine tipped over or that the controls for the leveling jacks were activated while the machine was still running after it had tipped over.
Order No. 7748976 was issued on September 10, 2002, under the provisions of Section 103 (k) of the Mine Act:
A fatal accident occurred at this operation on September 10, 2002 when the Ingersoll-Rand T-4 drill overturned on the drill operator. This order is issued to assure the safety of persons at this operation and prohibits any work in the affected area until MSHA determines that it is safe to resume normal operations as determined by an Authorized Representative of the Secretary of Labor. The mine operator shall obtain approval from an authorized representative for all action to recover and/or restore operations in the affected area.This order was terminated on September 25, 2002. The Ingersoll-Rand T-4 drill has been permanently removed from the mine property. The mine operator can resume normal operations.
Related Fatal Alert Bulletin:
FAB02M25
APPENDIX A
Persons Participating in the Investigation
Redland Genstar, Inc.
Patrick Reilly .......... Plant Manager
Joseph N. Ayers .......... Safety & Environmental Manager
Irvin L. Maurer CPG .......... Manager-Natural Resources
G. Edgar Harr Son's Corp.
Paul M. Fabiszak .......... President
Sandy Cochran .......... CEO
Ingersoll-Rand Company
Norris M. Houston .......... Field Service Manager
Edward Cashner .......... Service Technician
Mine Safety & Health Administration
Kenneth A. Amati .......... Mine Safety and Health Inspector
Donald L. Ratliff .......... Mine Safety and Health Inspector
F. Terry Marshall .......... Mechanical Engineer (Technical Support)
Michael Hancher .......... Mine Safety and Health Specialist
Darren Blank .......... Civil Engineer (Technical Support)
Cynthia Shumiloff .......... Mine Safety and Health Specialist
Andrea Appel .......... DOL Solicitor
APPENDIX B
Persons Interviewed
Redland Genstar, Inc.
Eugene Fritz .......... Powder Person
Benjamin Tyeryar .......... Supervisor of Shipping
Dennis J. Oxley .......... Dispatcher
Larry Miller .......... Pit Supervisor
G. Edgar Harr Son's Corp.
Paul Fabriszak .......... President
Sandy Cochran .......... CEO
Explo-Tech
Dale E. Reese .......... Blaster
Sabate Hauling
Dwayne Steinterb .......... Truck Driver