DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
District 7
Accident Investigation Report
(Surface Area of Underground Mine)
Fatal Machinery Accident
Mine # 3-2 (I.D. No. 40-01977)
U.S. Coal, Inc.
Smokey Junction, Scott County, Tennessee
June 13, 1997
by
Billy Griffin
Coal Mine Inspector
ORIGINATING OFFICE - MINE SAFETY AND HEALTH ADMINISTRATION
HC 66 BOX 1762, BARBOURVILLE, KENTUCKY 40906
JOSEPH W. PAVLOVICH, DISTRICT MANAGER
Report Release Date: January 20, 1998
OVERVIEW
On Friday, June 13, 1997, a mechanic was fatally injured while repairing a lift jack on a Caterpillar Model 980C Front End Loader. A steel "I" beam failed while being used as a strut to support the loader arm frame assembly and bucket. The bucket dropped, pinning the victim between the bucket and the ground.
The accident occurred as a direct result of the mine operator's failure to insure that secure blocking procedures were used on the loader bucket before performing repairs beneath the raised bucket.
U.S. Coal, Inc. Mine # 3-2 is located at Smokey Junction, Scott County, Tennessee. Coal is mined from the Jellico seam. U.S. Coal, Inc. is a solely owned corporation. The property mined is owned by Ms. Janice Bible, 9133 Wesley Place, Knoxville, TN 37922 and Ms. Linda Bray Rutledge, 246 Beauregard Heights, Hampton, VA 23669.
The corporate officers are:
James K. Bale...................................President
William M. Bale................................Secretary/Treasurer
Lester D. Bale...................................Assistant Secretary/Treasurer
The mine began operation in October, 1982. Twenty-nine underground miners are employed at the mine, one production shift per day, five days per week. The mine utilizes the mains and room development method of mining using a Jeffery Continuous mining machine along with a mobile bridge haulage system.
DESCRIPTION OF THE ACCIDENT
On Friday, June 13, 1997, the shift began at approximately 7:00 a.m. and progressed normally at approximately 10:00 a.m. Jim Smiddy, Superintendent of the coal preparation facility instructed Danny Foster, loader operator, to tram a Caterpillar, Model 980C front end loader to a proposed mine site and to perform some excavation work.
While operating the front end loader at new mine location, Foster, observed a leak in the right boomjack of the machine. Foster reported by radio the condition to Mark Mills, Mining Engineer who instructed him to tram the front end loader to the nearby #3-2 underground mine site.
Mills, informed Smiddy by radio that repairs to the front end loader were necessary and Mills then left the mine. Odeva Muse, a mechanic who was also at the proposed mine site, trammed the loader to the nearby #3-2 mine site to await repairs while Foster traveled to the site. Next, Smiddy instructed James E. Calhoun, Mechanic and victim to travel to the #3-2 mine site to repair the front end loader. Calhoun, left the coal preparation plant at approximately 11:40 a.m. and arrived at the #3-2 mine site at approximately 1:30 p.m. to begin the repairs. Shane Chambers, Mine Superintendent, examined the area where repairs were to be made at approximately 2:08 p.m. and left the area. Calhoun examined the loader and made an assessment of needed repairs. According to Mills the leaking boomjack would need to be repaired. Muse, Foster, and Calhoun prepared to make repairs to the loader by installing a damaged steel "I" beam with a metal strap and wooden block wedge, which was found at the mine site, as a strut between the yoke on the rod and the cap of one of the bucket lift cylinders. This was a field fabricated device intended for this purpose. This device was made by Calhoun on the day of the accident. The metal strap, which was attached to the strut with two bolts, was placed around the cylinder rod. The wooden block was wedged in between the side of the strut and the boom arm. After the strut was in position, the loader arms were lowered putting pressure on the strut. The hydraulic pressure to the lift cylinders was then relieved and all the load from the weight of the loader arm and bucket was transferred to the strut. Muse and Newport were removing the boom jack while Calhoun was assisting from beneath the raised bucket.
At approximately 3:08 p.m., the metal "I" beam strut being used to secure the loader arm frame assembly and bucket failed, allowing the bucket and boom to fall, striking the victim and resulting in fatal injuries. Chambers, who had returned to the area after being notified, called the Scott County Ambulance Service after performing CPR and administering first aid to the victim with no response. The Scott County Ambulance Service arrived at the mine site at approximately 3:45 p.m. No vital sounds were found. The victim was transported to the Scott County Hospital where he was pronounced dead at approximately 4:00 p.m. by Dr. Jan Robbins.
INVESTIGATION
At approximately 3:20 p.m., Mark Mills, Mining Engineer telephoned MSHA's Barbourville District Office and informed John Pyles, Assistant District Manager, of the accident. Pyles immediately dispatched investigators to the site.
During the course of the investigation, assistance was requested of MSHA's Pittsburgh Safety & Health Technology Center to provide technical and engineering evaluation of the steel strut and associated devices. Terence M. Taylor, Civil Engineer, performed these evaluations and provided the Executive Summary of the Evaluation of Failed Steel Strut, which includes his findings and conclusion.
PHYSICAL FACTORS INVOLVED
The following physical factors were determined to be relevant to the occurrence of the accident.
- The accident occurred at the surface area of the U.S. Coal,
Inc., Mine # 3-2, I.D. No. 40-01977.
- The Loader involved was a Caterpillar, Model 980c Front End
Loader, serial number CAT-980-C 63 X 05482, (no Company
number).
- A damaged "I" beam measuring 32.5 inches x 6 inches x 3.57
inches was being used as a strut to support the loader arm
frame assembly while repairs were conducted on the right
boom jack of the front end loader.
- The estimated load (weight) of the front end loader's arm
frame assembly and bucket was 60,000 pounds.
- The victim was pinned between the loader bucket and ground
when the "I" beam failed and the bucket dropped to the
ground.
- The failed "I" beam was obtained by MSHA investigators for
testing and evaluation.
- The examination and test results conducted on the steel "I"
beam determined that the beam failed because the previous
damage changed the cross sectional properties of the beam
effectively lowering the beam yield strength.
- The method used by the mine operator to support the loader arm frame assembly was not in accordance with the method stipulated in the service manual provided by the equipment manufacturer.
DISCUSSION
The use of a single support strut, wedged in place to facilitate the repair to the lift cylinder was not a safe method to secure the raised loader arm frame assembly and bucket as recommended in the equipment manufacture's service manual. According to the service manual for the subject model front end loader the procedure required the use of two vertical stands to support the weights of the loader arm frame assembly and bucket, while conducting maintenance on the left cylinders.
Additionally an examination and analysis of the "I" beam used as a steel strut revealed that, prior to its use at the accident site, the steel beam had been damaged by welding and cutting. The damage to the "I" beam was visually obvious. According to the AISC Manual of Steel Construction, a new steel S 6 X 17.25 section, "I" beam, if adequately held into position, would have the capacity to safely carry a concentric load of 93,000 pounds. In comparison, a load of 60,000 pounds was estimated by engineering methods to have been applied on the damaged "I" beam at the time of the accident. Evaluation of the effects the previous damage had on the "I" beam used at the accident site indicated the damage had the effect of changing the cross sectional properties from an "I-shaped" section to a "T-shaped" section. A "T-shaped" section is considerably weaker in compression and bending.
Muse, began working at surface mines in 1975 and performed welding and mechanical duties until the time of this accident. He received his Annual Refresher Training on 5/12/97.
Newport, began surface mining duties as a general laborer in July 1995. He continued these duties until the time of this accident. He received his Annual Refresher Training on 5/12/97.
Calhoun, had twenty years experience as a surface mine mechanic. He had performed these duties until the time of this accident. He received Annual Refresher Training on 5/12/97.
CONCLUSION
The device used by the miners to support the loader arm frame assembly and bucket, was a poorly field-fabricated and damaged "I" beam with little or no aspects of engineering design or considerations that would ensure the device would secure the raised bucket with an acceptable margin of safety.
ENFORCEMENT ACTIONS
- A 103-K Order No. 4073828 was issued to provide for the
safety of all persons on the surface of the mine until the
investigation was complete.
- A 104-A Citation No. 4073933 was issued for failure to securely block the boom and bucket assembly on the Caterpillar 980C front end loader.
Respectfully submitted by:
Billy Griffin
Accident Investigator
Approved by:
John M. Pyles
Assistant District Manager
and
Joseph W. Pavlovich
District Manager
Related Fatal Alert Bulletin:
FAB97C14