DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
Metal and NonMetal Safety and Health
REPORT OF INVESTIGATION
Surface Nonmetal Mine
(Limestone)
Fatal Powered Haulage Accident
September 13, 2000
Canarico Quarries
Canarico Quarries, Inc.
Juana Diaz, Puerto Rico
Mine I.D. 54-00159
Accident Investigators
Juan A. P�rez
Supervisory Mine Safety and Health Inspector
Roberto Torres-Aponte
Mine Safety and Health Inspector
Armando Pe�a
Mine Safety and Health Inspector
Dennis Ferlich
Mechanical Engineer
Ronald Chambers
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
On September 13, 2000, Freddy Santiago, skid loader operator, age 28, was fatally injured as he either leaned over in the seat or attempted to exit the skid loader and accidently activated the controls, causing the bucket to lower and pin him between the cross-bar member of the boom and the frame structure.
The accident occurred because the safety mechanisms that prevented the bucket from accidently lowering had been altered or removed. Failure to adequately inspect the equipment to detect such safety defects was a contributing factor.
Santiago had a total of one year and four months mining experience, all with this company. He had not received training in accordance with 30 CFR Part 48.
Canarico Quarries, a crushed limestone operation, owned and operated by Canarico Quarries, Inc., was located on Road 552, Guayabal Ward, Juana Diaz, Puerto Rico. The principal operating official was Carlos Torres, operation manager. The mine was normally operated two, 8-hour shifts a day, five days a week. Total employment was 82 persons.
The mine consisted of a multiple-bench quarry accessed by declined roadways. After overburden was removed, the material was drilled, blasted, and loaded into haul trucks. Limestone was transported to the primary mill where it was crushed, sized and stockpiled. The finish product was sold for construction aggregate.
The last regular inspection at this operation was completed September 11, 2000.
On the day of the accident, Freddy Santiago (victim) reported for work at 11:00 a.m., his normal starting time. Jaime Rodriguez, group leader, assigned Santiago and three other co-workers to clean up spillage from around the tunnel conveyor of the secondary plant. While the three employees were shoveling material from under and around the conveyor, Santiago operated the skid loader to move the material to another area.
At 5:00 p.m., the crew had finished cleaning up spilled material at the secondary plant and was instructed to go to the primary plant to clean up spillage and grease the equipment.
About 6:00 p.m., Hiram Cruz, cleanup man, was repairing a grease hose and observed Santiago drive the skid loader around the conveyor and stop approximately 30 feet away from where Cruz was working. After a time, Cruz noticed that the skid loader had not been moved for a while and went to check on Santiago. He found Santiago inside the operator's compartment, leaning forward, pinned between the crossbar member of the boom and the frame structure of the loader. He tried to free Santiago but was unable to do so. Cruz immediately alerted his co-workers, then went to the shop to call for assistance. Santiago was removed from the loader and transported in a company vehicle to a local hospital. He was then taken by medical personnel to a regional hospital where he was pronounced dead as a result of severe head injuries.
MSHA was notified of the accident at 10:00 p.m., on September 13, 2000, by a telephone call from Efrain Carreras, vice president of Canarico Quarries, Inc., to Edward Lopez, accident investigation program manager. An investigation was started the next day. MSHA's accident investigation team 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. An order was issued under the provisions of Section 103(K) of the Act to ensure the safety of miners. MSHA conducted the investigation with the assistance of mine management and mine employees. The miners did not request nor have representation during the investigation.
The skid loader involved in the accident was a GEHL model 3825 skid loader, serial no. 8598, manufactured in 1993. It was powered by a Kubota Model V1305B, four cylinder, 81 CID diesel engine, rated at SAE 33.5 HP at 3000 RPM. It was hydrostatically driven with hydrostatic power supplied by a tandem-mounted direct drive hydrostatic pump. Power was transferred from the hydrostatic pump to the front and rear wheels through drive chains. Propulsion and hydrostatic braking were controlled by a single hand control T-bar lever. The skid loader's empty weight was approximately 3,400 pounds. It was equipped with an eight cubic-foot bucket with a specified maximum operating capacity of 1,000 pounds. A structure for roll-over protection (ROPS) and overhead fall protection (FOPS) was also provided. The loader was approximately 107 inches long (including the bucket), 54 inches wide, and 70 inches high to the top of the ROPS/FOPS. The wheel base was approximately 34 inches from the front center axle to the rear center axle. Power King 7x 8.5x15 tires were installed on the skid loader. The hour meter read 525.6 hours.
The ROPS/FOPS, model no. S 121158, was manufactured to fit the GEHL skid loaders, model SL3725 and SL3825. The structure included a rear window and cage guarding on both the left and right sides. The front, which was the operator's compartment entry, was open.
The bucket was an eight cubic-foot bucket with a maximum specified weight carrying capacity of 1,000 pounds. The bucket was approximately 54 inches wide, 24 inches high, and 24 inches deep.
The operator's compartment was approximately 30 inches wide with a distance of approximately 28 � inches from the seat back to the front inside edge of the front compartment panel. The floor to seat bottom height was approximately 24 inches and the total floor to inside cab height was approximately 57 inches. A seat belt and operator secondary restraint bar were included as standard equipment. The operator's compartment contained all of the warning and danger decals as specified in the operator's manual for the GEHL 3725/3825 skid loader, Form No. 906376.
Engine start/run/off functions were controlled by a key switch. The skid loader had two side-mounted, self-centering T-bar hand controls. One T-bar hand control was located on the forward left side of the operator's seat, and the other T-bar hand control was located on the forward right side of the operator's seat, as viewed from sitting on the seat. The left T-bar controlled the loader's propulsion and steering functions. Pushing and pulling the left T-bar caused forward and reverse movement, respectively. Twisting the left T-bar clockwise turned the loader to the right, and twisting it counter-clockwise turned the loader to the left. The right T-bar controlled the lift arm raise/lower functions and the bucket tilt up/down functions. Pushing and pulling the right T-bar lowered and raised the lift arms, respectively. Twisting the right T-bar clockwise tilted the bucket downward, and twisting it counter-clockwise tilted the bucket upward. Engine throttle speed was controlled by a hand lever located on the forward right side of the operator's compartment. Pushing the throttle lever forward increased engine speed and pulling it rearward decreased engine speed.
The two T-bar hand controls for the loader propulsion/steering and the lift arm/bucket functions were tested by operating the loader. The two T-bar hand controls functioned as specified in the operator's manual for the GEHL 3725/3825 skid loader, Form No. 906376, when operating the machine on a nearly level surface where the accident occurred. Motion was observed to be smooth and responsive. When the T-bar hand controls were released, they centered to neutral position as specified.
The engine throttle control was tested by moving the throttle lever through its speed range. The engine throttle lever moved smoothly and engine speed increased and decreased as expected with no audible engine problems.
The key switch was tested by trying to start the engine. On the first attempt to start the loader after the accident, turning the key switch to the start position did not result in cranking of the starter. The main 30 amp fuse located on the instrument panel was removed, tested, and inspected. Continuity testing of the fuse showed it was defective, i.e., testing resulted in an open circuit. Visual inspection of the fuse showed that burn marks were present across the length of the fuse and two pieces of copper wire had been installed across the outside length of the fuse. This showed that the fuse had been defective, and the two copper wires were placed across the fuse contacts instead of replacing the fuse with a new 30 amp fuse designed for this application. After replacement of a temporary fuse, the engine started when the key switch was placed in the "start" position. With the key switch in the "run" position, the engine continued to run. When the key switch was moved to the "off" position, the engine continued to run. The "key switch off" position failed to shut off the engine as specified in the operator's manual. The operator shut the engine off by pulling a wire that was directly attached to the fuel injection pump shutoff mechanism in the engine compartment. Inspection of this pull wire showed it appeared to be fabricated from a length of red electrical wire estimated to be approximately 16 gauge electrical wire. This type of engine shut off mechanism was not specified in the design features or functional operating features of the operator's manual. With the key switch malfunctioning in the "off" position, the lift arm disable safety feature was defeated.
To provide operator safety, the skid loader was designed with safety interlock systems composed of solenoid valves, switches, and relays. The interlocks functioned to: 1) prevent starting of the engine unless the operator was sitting in the seat and the operator restraint bar was down, and 2) disable the lift arm raise/lower functions and the bucket roll functions anytime the operator left the seat, turned off the key switch, or raised the restraint bar. A lift cylinder mechanical lock was located on the left lift cylinder to be used as a cylinder block to prevent unexpected lowering of the lift arm while servicing the loader.
The safety interlock features were tested to determine if they functioned as specified in the operator's manual for GEHL 3725/3825 skid loaders, Form 906376. With the operator sitting in the seat, the restraint bar was left in the upward position and the key switch was turned to the "start" position. The engine started, showing the restraint bar interlock was nonfunctional. The key was turned to the "start" position while the restraint bar was in the upward position and the operator was raised off the seat (no pressure on the seat). The engine started, showing the seat pressure interlock was nonfunctional. To test the lift arm lockout feature, the engine was run and the lift arm was hydraulically raised to the upward position. The engine was shut off and the lift arm T-bar hand control was moved forward. The lift arm dropped immediately, showing the "key switch off" hydraulic lock feature was not functioning as specified in the operator's manual. This test was repeated with the restraint bar in the upward position and the engine running. When the lift arm T-bar hand control was moved forward, the lift arm again dropped immediately, showing the "restraint bar up" position did not disable the lift arm raise/lower functions as specified in the operators manual.
The causes of the malfunctions were investigated and the following were found: the electrical connector from the main wiring harness to the seat pressure switch was disconnected and the electrical connector from the main wiring harness to the restraint bar switch was connected to the restraint bar switch connector. These wires were identified by the color coding specified on the loader wiring diagram, Figure 36, in the operator's manual, Form 906376. The seat was removed to examine the seat pressure switch, but the seat pressure switch had been previously removed and was not present. Indentations, approximately 1/8 to 1/4 inches deep, caused by the seat pressure switch, which had been removed, were visually observed in the foam cushion of the seat bottom. Impressions caused by the seat pressure switch which had been removed were visually observed in the foam cushion of the seat bottom. Visual inspection of the two wires leading from the main panel wiring harness to the restraint bar switch connector showed that these two wires had approximately � inch long sections of insulation stripped from each wire about one inch back from the connector. The wires leading from the main wiring harness and the wires on the switch side of the connectors were twisted together, but the stripped bare wire sections were separated and were not contacting each other when visually examined after the accident. The restraint bar was removed and a continuity test was performed on the switch using a volt-ohm meter. Continuity testing of the restraint bar switch showed it was defective, i.e., the switch was continuously open whether the contacts were open or closed. Visual Inspection of the wiring harness inside the instrument panel showed that two connectors were disconnected and one black wire was separated. The function of these wires was not identified, and the cause of the malfunctioning key switch was not determined during the field investigation.
A product safety engineer at GEHL Company was contacted and the design and operation of the safety interlock system was discussed. The following was determined: the safety interlock system was designed as a fail safe system; an open circuit in any of the electrical wiring, switches, and/or relays, such as disconnection of the seat pressure switch or restraint bar switch, or separation of an electrical wire, would result in activation of the interlock features. Activation of the interlock features would disable the lift arm and bucket hydraulics, and if not running, would prevent the engine from starting. The switch used in the seat was a mechanical plunger switch, and the switch used in the restraint bar was a reed magnetic switch. Both switches were normally open switches, and they were wired in series. The relays were normally open relays, and the solenoid valves for locking out the hydraulic functions were normally closed valves. In order to operate the lift arm and bucket hydraulic functions, power had to be supplied to the electrically actuated solenoid valves through the switches and relays. With normally open switches, disconnection of either or both switches at the wiring harness connectors acts the same as if either the seat pressure switch or restraint bar switch were open.
The field investigation showed that all functions of the safety interlock system were defeated. This allowed the machine to be started without the operator in the seat and without the restraint bar down. Also, this allowed operation of the lift arm raise/lower functions and the bucket roll functions while the operator was not seated, had the restraint bar up, or when the key was in the "off" position. Although specific problems were identified, i.e., no seat pressure switch, the defective restraint bar switch, and the malfunctioning key switch, the specific method used to defeat the safety interlock system was not determined.
Upon arrival at the accident site, the victim's hard hat was found resting against the rear inside wall of the cab between the left side of the operator's seat and the left side of the cab. The hard hat was located underneath the left hinge of the restraint bar with the brim of the hard hat facing down and the underside of the hard hat resting against the rear wall of the cab. When visually examined, no blood was found on the restraint bar. The ability to lower the restraint bar to the normal operating position was checked with the hard hat in this location, and it was found that the restraint bar could not be completely lowered. The lack of visible blood on the restraint bar and the inability to lower the restraint bar with the hard hat located underneath the restraint bar hinge, indicated that the restraint bar was in the upward position at the time of the accident.
Visual inspection of the seat belt showed that the male portion of the seat belt was missing. Only the plastic sheath was present, making the seat belt nonfunctional.
The hydraulic fluid level sight gauge was visibly observed and no hydraulic fluid was present in the sight gauge. Operational testing of the hydraulics with the machine on nearly level surface showed that the hydraulics functioned as specified in the operator's manual for the GEHL 3725/3825 skid loaders, even though the fluid level was considered below the desired level.
The root cause of the accident was management's failure to ensure that the safety equipment installed on the loader was maintained in safe, operational condition. Contributing to the accident was management's failure to ensure adequate equipment inspections were conducted prior to placing equipment into service.
Order No. 7797270 was issued on September 14, 2000, under the provisions of Section 103(k) of the Mine Act:
A fatal accident occurred in the primary crusher area where an employee sustained fatal head injuries. This order is issued to assure the safety of persons at this operation until the affected areas can be returned to normal operations as determined by an authorized representative of the secretary. The operator shall obtain approval from an authorized representative for all actions to return affected area.This order was terminated on September 16, 2000. The GEHL 3825 skid loader involved in the accident had been permanently removed from the site and the mine could safely resume operations.
Citation No. 7797478 was issued on September 15, 2000, under provisions of 104(d)(1) of the Mine Act for violation of 30 CFR 56.14100(b):
A skid loader operator was fatally injured at this operation on September 13, 2000, when he was caught between the boom cross member and the frame of the GEHL Model 3825 loader. The safety device for the restraint bar had been disconnected and by-passed, the safety device for the operator's seat had been removed and the safety device for the starting switch had been disabled. Any of these devices, in proper working order, would have prevented the boom from lowering and pinning the victim. Management engaged in aggravated conduct constituting more than ordinary negligence by allowing the loader to be operated in this condition. This violation is an unwarrantable failure to comply with a mandatory standard.This citation was terminated on October 4, 2000. The GEHL 3825 skid loader had been permanently removed from the operation. Employees had been trained in the proper use and maintenance of skid loaders.
Citation No. 7797479 was issued on September 15, 2000, under provisions of 104(a) of the Mine Act for violation of 30 CFR 56.14100(a):
A skid loader operator was fatally injured on September 13, 2000, when he was caught between the boom cross member and the frame of the GEHL mode 3825 loader. Adequate mobile equipment inspections were not being conducted prior to placing the equipment into service as evidenced by the number of defects found on this skid-steer loader during the investigation. The company failed to ensure the proper procedures were followed when inspecting mobile equipment prior to its use.This citation was terminated on October 13, 2000. The mine operator has re-trained all mobile equipment operators on the requirements to make adequate daily safety inspections.
Related Fatal Alert Bulletin:
FAB2000M39
A. Persons Participating in the Investigation
B. Persons Interviewed
Persons Participating in the Investigation:
Canarico Quarries, Inc.
Carlos Torres . . . . . . . . . . . . . . . . . . . . . . . production managerMine Safety and Health Administration
Efrain Carreras . . . . . . . . . . . . . . . . . . . . . . vice president
Julio Alvarado . . . . . . . . . . . . . . . . . . . . . . .assistant production manager
Melba Figueroa . . . . . . . . . . . . . . . . . . . . . .president
Juan A. P�rez . . . . . . . . . . . . . . . . . . . . . . . supervisory mine safety and health inspector
Roberto Torres-Aponte . . . . . . . . . . . . . . . .mine safety and health inspector
Armando Pe�a . . . . . . . . . . . . . . . . . . . . . . mine safety and health inspector
Dennis Ferlich . . . . . . . . . . . . . . . . . . . . . . . mechanical engineer
Ronald Chambers . . . . . . . . . . . . . . . . . . . . training specialist
Persons Interviewed:
Canarico Quarries, Inc.
Carlos Torres . . . . . . . . . . . . . . . . . . . . . . . operation managerProductora de Agregados, Inc.
Julio Alvarado . . . . . . . . . . . . . . . . . . . . . . . assistant production manager
Pedro Rodriguez . . . . . . . . . . . . . . . . . . . . . mechanic
Esteban Alvarado . . . . . . . . . . . . . . . . . . . . .electrician
Jaime Rodriguez . . . . . . . . . . . . . . . . . . . . . .group leader
Felix Estrella . . . . . . . . . . . . . . . . . . . . . . . . .front-end loader operator
Hiram Cruz . . . . . . . . . . . . . . . . . . . . . . . . . clean-up man
Narciso Cruz . . . . . . . . . . . . . . . . . . . . . . . .clean-up man
Jos' Cruz . . . . . . . . . . . . . . . . . . . . . . . . . . clean-up man
Edrik Lopez . . . . . . . . . . . . . . . . . . . . . . . .supervisor assistant
Geraldo de Jesus . . . . . . . . . . . . . . . . . . . . .mechanic
Oscar Sierra . . . . . . . . . . . . . . . . . . . . . . . . mechanic
Luis Alvarado . . . . . . . . . . . . . . . . . . . . . . . front-end loader operator
Samuel Figueroa . . . . . . . . . . . . . . . . . . . . . greaser
Jos' Casiano . . . . . . . . . . . . . . . . . . . . . . . .mechanic
Jimmy Aponte . . . . . . . . . . . . . . . . . . . . . . . mechanic help
Jesus Torres . . . . . . . . . . . . . . . . . . . . . . . . truck driver
Ismael Rosello . . . . . . . . . . . . . . . . . . . . . . .supervisor
Carlos Arroyo . . . . . . . . . . . . . . . . . . . . . . .mechanicReyes Electrical Machine Shop (Taller Reyes)
Angel Nater . . . . . . . . . . . . . . . . . . . . . . . . plant supervisor
Antonio Rosario . . . . . . . . . . . . . . . . . . . . . mechanic
Marcelino Rivera . . . . . . . . . . . . . . . . . . . . .mechanic helper
Jos' Diaz . . . . . . . . . . . . . . . . . . . . . . . . . . supervisor
Elias Morales . . . . . . . . . . . . . . . . . . . . . . . supervisor
Alejandro Pedraza . . . . . . . . . . . . . . . . . . . mechanic
Jos' Ferrer . . . . . . . . . . . . . . . . . . . . . . . . .mechanic
Jorge Ortiz . . . . . . . . . . . . . . . . . . . . . . . . .mechanic helper
Javier Rivera . . . . . . . . . . . . . . . . . . . . . . . electrician (former employee)
Frank Reyes . . . . . . . . . . . . . . . . . . . . . . . electromechanic and owner