ISSUE DATE: 4/01/2011 

PROGRAM INFORMATION BULLETIN NO. P11-20

FROM: KEVIN G. STRICKLIN

 Administrator for

 Coal Mine Safety and Health

 LINDA F. ZEILER

 Acting Director of Technical Support

SUBJECT: Re-Issue of P09-26 - Potential Hazard to Roof Bolting Machine

 Operators Due to Inadvertent Control Actuation

Who needs this information?

Underground coal miners, operators of underground coal mines, manufacturers of roof 

bolting machines, and Coal Mine Safety and Health (CMS&H) personnel.

What is the purpose of this bulletin?

The purpose of this Program Information Bulletin (PIB) is to alert the coal mining 

industry and CMS&H personnel to a potential hazard to roof bolting machine operators 

due to the sudden movement of the machine or machine components caused by the 

inadvertent actuation of machine controls.

Information

The investigation of a fatal machinery accident revealed that a potential hazard exists 

on roof bolting machines with machine controls that are not protected against 

unintentional activation. This hazard is increased when an operator is at the drill 

station and, at the same time, controls at other operating stations on the same machine 

can unintentionally actuate machine functions. Although the fatality occurred when an 

Automated Temporary Roof Support (ATRS) control was inadvertently actuated on a 

bolting machine retrofitted with a Safe Shield ATRS system, potential hazards exist 

from other inadvertent control actuations as well. Likewise, inadvertent control 

actuations can occur at unattended controls on other bolting machines.
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To prevent similar accidents, the following measures should be taken:

• ATRS and other machine controls should be protected from accidental

activation that may result in the machine or machine components coming

in contact with the operator. Unintentional control activation can be

prevented through one or more of the following means:

o The controls can be relocated to a protected position.

o The controls can be guarded in their existing location.

o The hydraulic system can be redesigned to prevent controls

at other operating stations from being active while the

operator is at the drill station. Diversion valves can be used

to divert the hydraulic flow from one operating station to

another to prevent controls from being active at more than one

operation station.

• Proper storage areas for supplies and materials should be provided on the 

bolting machine. Care must be taken to avoid placing materials in locations

where they could interfere with or fall on machine controls.

We have provided the district offices with additional information that addresses 

specific means of preventing inadvertent actuation of machine controls and other means 

of mitigating the safety hazards outlined in this bulletin. The local District Manager can 

be contacted to obtain this information.

What is the background for this PIB?

A roof bolting machine operator was fatally injured when the ATRS controls were 

inadvertently actuated, causing the ATRS system to unexpectedly retract and strike the 

operator at the drilling control location. Investigation findings support a conclusion 

that a box containing two resin cartridges fell from the top of the machine onto the 

ATRS controls situated in the operator’s compartment at the side of the machine. The 

operator was crushed between the ATRS and the machine. In this accident, the ATRS 

system involved was retrofitted by Safe Shield Corporation of Richlands, Virginia, and 

featured a “tilt” jack which folded the ATRS onto the drill boom for tramming from 

place to place. The tilt jack control was accidentally struck and activated by the resin 

box. On the machine involved in the accident, the ATRS would fold onto the drill boom 

from the full upright position in approximately one second when the ATRS tilt control 

was fully activated. Following the fatal accident, the subject machine was retrofitted 

with diversion valves to deactivate all the controls in the operating compartment when 

the drilling controls were being operated. The retrofit work also included the addition 
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of a small orifice in the hydraulic line of the ATRS tilt jack to slow the speed of the 

ATRS while it folds onto the drill boom.

What is MSHA’s authority for this PIB?

The Federal Mine Safety and Health Act of 1977, as amended, 30 U.S.C. § 801 et seq.; 

30 C.F.R. part 75, subpart C.

Who are the MSHA contact person for this PIB?

Coal Mine Safety and Health, Division of Safety

Johnny P. Calhoun, (202) 693-9507

E-mail: calhoun.johnny@dol.gov

Technical Support, Pittsburgh Safety and Health Technology Center

William Gray, (412) 386-6787

E-mail: gray.william@dol.gov

Technical Support, Approval and Certification Center

Eugene D. Hennen, (304) 547-2057

E-mail: hennen.eugene@dol.gov

Is this PIB on the Internet?

This PIB may be viewed on the Internet by accessing the Mine Safety and Health 

Administration (MSHA) home page (www.msha.gov) and then choosing “Compliance 

Info” and “Program Information Bulletins.”

Who will receive this PIB?

MSHA Program Policy Manual Holders

Underground Coal Mine Operators

Roof Bolting Machine Manufacturers

Coal Special Interest Groups