ISSUE DATE: 3/23/2011 

PROGRAM INFORMATION BULLETIN NO. P11-14 

FROM: KEVIN G. STRICKLIN 

 Administrator for 

 Coal Mine Safety and Health 

 NEAL H. MERRIFIELD 

 Administrator for 

 Metal and Nonmetal Mine Safety and Health 

 LINDA F. ZEILER 

 Acting Director for Technical Support 

SUBJECT: Reissue of P08-03 - Use of Stabilizers (Outriggers) on 

 Chassis-Mounted Drills and Cranes 

Who needs this information?

Mine operators, independent contractors, mobile equipment operators, miners' 

representatives, Mine Safety and Health Administration (MSHA) enforcement 

personnel, and other interested parties should have this information. 

What is the Purpose of this Program Information Bulletin?

This Program Information Bulletin (PIB) informs all mobile equipment operators that 

stabilizers are considered to be safety devices that should be used and maintained in 

accordance with the original equipment manufacturer's specifications. 

Types of Equipment Involved:

This PIB applies to chassis-mounted drills and cranes provided with stabilizers. 

Information

Stabilizers are used to level and stabilize chassis-mounted drills and cranes after the 
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equipment is moved to a location where it will be used. For example, the operator of a 

truck crane will deploy the stabilizers prior to picking up and swinging a load, as will a 

drill operator prior to elevating the mast. 
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Stabilizers are part of an integrated safety system that includes: 1) the stabilizer and its 

hardware (its ground-engaging base, hydraulically- or mechanically-operated vertical 

and horizontal jacking or positioning equipment, all fasteners and attachment devices); 

2) load-spreading cribbing, timbers, mats or pads under the stabilizer bases; and 3) the 

ground itself. 

The stabilizer should be structurally sound throughout and maintained in accordance 

with the equipment manufacturer's instructions. Structural members, attachment 

devices, welds, fasteners and jacks should be in place and inspected for cracks, wear, 

rust, corrosion or other damage that could affect their integrity or ability to carry or 

transfer a load. Hydraulic systems should be inspected for cylinder or hose wear, 

cracks, leaks or other damage or defects that could result in loss of hydraulic pressure 

while under load. 

Because stabilizers transfer the weight of the equipment, its live loads and dynamic 

forces to the ground, ground conditions play a significant role in the stability of the 

machine and the ultimate safety of the operator and persons working nearby. Ground 

conditions that should be considered include the soil's load-bearing capacity, surface 

slope and evenness, the presence of nearby or previously backfilled excavations, and 

subsurface cavities. Soil support conditions should be similar under each stabilizer pad. 

Management and equipment operators should evaluate ground conditions before and 

during operation to ensure unsafe ground conditions do not develop. 

Due to varying ground conditions and soil strengths, stabilizer bases are not necessarily 

large enough in their ground contact area to safely transmit all forces to the ground. 

Load-spreading devices such as cribbing, timbers, mats or pads may be required to 

spread the load over a sufficiently-sized area to support the machine during operation 

and prevent failure of the ground below. Supports placed under outrigger pads should 

be structurally sound, firmly and evenly supported and of adequate size. If these 

supports remain under outrigger pads for an extended period of time, they should be 

inspected often to ensure they have not shifted or deteriorated, and that the condition of 

the ground beneath remains sound. 

Mine operators should obtain from the manufacturer the equipment's side-to-side and 

front-to-back load/lift limits and maximum operating slope conditions. Mine operators 

should also train equipment operators and supervisors to know, understand and 

adhere to those limits and ensure that they are not exceeded. Hard copies of operating 

manuals and safe operating instructions should be provided during task training and 

for permanent reference in the cab of the equipment. Pre-setup risk assessments should 

always be performed and appropriate control measures taken. Special precautions 

should be taken to assure safety when highly unusual conditions exist, such as when 

soils are particularly weak, ground conditions are deteriorating or loads or operating 

parameters approach the limits of the machine's safe operating range. 
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Before operating stabilizer-equipped machines, equipment operators should assure all 

stabilizers are in serviceable condition and rest firmly on ground capable of supporting 

the machine during all phases of its operation. Stabilizers should be fully extended to 

prevent machine tip-over, unless otherwise permitted by the equipment manufacturer. 

When space constraints prohibit full extension of stabilizers, machines should either be 

repositioned to allow for full extension of stabilizers or loads should be reduced to 

maintain stability and prevent exceeding lifting limits specified by the manufacturer. 

While elevating and operating the machine, operators should be alert to ground 

subsidence and the machine going out of level, as differential settlement could indicate 

impending failure of the stabilizers or the ground. Shifting loads, changing forces or 

the failure of a jack or the ground beneath it could result in the machine overturning. 

What is the background for this PIB?

A fatal accident occurred when a drilling rig overturned while it was being operated on 

a sloped surface. Two other fatal accidents occurred when mobile cranes overturned 

while lifting material. Accident investigations indicate that improper utilization of the 

stabilizers, inadequate training, and failure to perform a pre-task risk assessment were, 

or may have been, contributing factors in these accidents. 

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. §§ 56/57.14100 Safety defects; examination, correction and records; 

30 C.F.R. §§ 56/57.14205 Machinery, equipment and tools; 30 C.F.R.§ 77.404(a) 

Machinery and equipment; operation and maintenance; 30 C.F.R. § 77.1606 Loading and 

haulage equipment; inspection and maintenance; 30 C.F.R. § 46.7 New task training; 30 

C.F.R. §§ 48.7 and 48.27 Training of miners assigned to a task in which they have had no 

previous experience. 

Where is this PIB on the Internet?

This PIB may be viewed on the World Wide Web by accessing MSHA's home page at 

www.msha.gov, choosing "Compliance Info" and "Program Information Bulletins." 

Who are the MSHA contact persons for this PIB?

Coal Mine Safety and Health, Division of Safety 

Johnny Calhoun (202) 693-9507 

E-mail: calhoun.johnny@dol.gov 

Coal Mine Safety and Health, Division of Safety 

John Arrington (202) 693-9549 

E-mail: arrington.john@dol.gov 
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Metal and Nonmetal Mine Safety and Health 

Marvin Lichtenfels, (202) 693-9600 

E-mail: lichtenfels.marvin@dol.gov 

Technical Support, Approval and Certification Center 

Ron Medina (304) 547-2059 

E-mail: medina.ronald@dol.gov 

Who will receive this PIB?

MSHA Program Policy Manual Holders 

Coal Mine Operators 

Metal and Nonmetal Mine Operators 

Miners' Representatives 

Independent Contractors 

Special Interest Groups