3 - The “R” in RCM—Pertinent Reliability Theory and Application

Abstract

Basic reliability concepts play a key role in the underlying philosophy of Reliability-Centered Maintenance (RCM), and in its implementation. The term RCM emphasizes the role that reliability theory and practice plays in properly focusing (or centering) preventive maintenance activities on the retention of the equipment's inherent design reliability. Reliability technology is at the very center of the maintenance philosophy and planning process. The key elements of reliability theory relevant to the RCM methodology include: (1) knowledge of a product or device failure density function (fdf) allows the calculations of the reliability parameters that may be of interest; (2) a key parameter in this regard is the failure rate; (3) one specific fdf frequently quoted and employed is the exponential fdf wherein λ = constant and is therefore independent of time; (4) a generally accepted depiction of a typical product life cycle known as the bathtub curve; and (5) whether a product or device follows the bathtub curve can have a profound impact on the proper selection of preventive maintenance (PM) tasks. Additionally, the failure mode and effects analysis (FMEA) forms the basis for virtually all subsequent reliability analyses and assessments because it forces an organization to systematically evaluate equipment and system weaknesses, and their interrelationships that can lead to product unreliability.