In the early 1970s RCM introduced the concept of criticality and a formal analysis for its determination. It applied an FMEA to specify the degraded states
of equipment and used the criticality level to gauge the level of mitigation needed for each degraded state. Maintenance technology has remained indebted
to RCM for these seminal advancements.
However, as a result of intensive work during the ‘80s implementing RCM in commercial nuclear power plants, the US Electric Power Research Institute (EPRI)
sponsored changes to the RCM process to make it faster, less expensive, more consistent, and more dynamic, and within a few years created a database by
which practitioners could benefit from world-class equipment expertize:
a. The lengthy RCM criticality analysis was replaced by a criticality checklist that is easily applied at the asset level.
b. RCM used two “bins” of criticality (critical and non-critical) but left the operating context as a continuum of unspecified variables. When two-part
binning of duty cycle and the service conditions was introduced, PM strategies could be summarized in PM Templates. Further, the FMEA can then be modified
to describe the asset type, instead of an instance of the asset type, as in RCM. The resulting FMEA Template is then applicable and easily updated
across all applications of the same asset type, whereas with RCM, a new asset of the same type in a different application needs a complete new analysis.
c. The nuclear industry’s RCM implementation program found that plant personnel usually lack the experience to develop accurate and comprehensive
descriptions of the degraded states, as well as failure patterns and time scales for degradation, which limited industry confidence in the resulting RCM
strategies. As a result Preventance authors developed the first purpose-built Templates under EPRI sponsorship in 1996 using equipment experts hand-picked
by leaders in the power industry. Over the following 8 years the Templates evolved into the EPRI PM Basis Database (PMBD) and APT’s equivalent PRO-M
desk-top application (under license to EPRI).
d. At this point using Templates could already be seen to be faster, cheaper, and more dynamic than RCM, with superior internal consistency and much more
engineering knowledge at hand. Preventance authors soon added enhancements going further beyond RCM: 1) the effectiveness of PM actions in mitigating
degraded states was quantified to improve on RCM’s vague “applicable and effective”, 2) a simple model was added for the decrease in task effectiveness
when a task interval was increased in relation to a wearout time, 3) the overall failure rate was estimated depending on PM task intervals and the
operating context.
e. Preventance, APT’s web-based successor to PRO-M, has now been benchmarked against independent published data, it accounts explicitly for task
repetitions, it includes modeling of the economic impacts and costs, and automatically searches for task combinations that improve the net benefit of a PM
strategy, while taking account of increased risk aversion for critical assets. During 2014 the data and technology were formally endorsed by the US Nuclear
Regulatory Commission.
f. RCM technology remains exactly where it was in the ‘70s. It can still be a useful tool in special circumstances but its history across many industries
of repeated failed sustainability due to high cost and lack of dynamic updating ability have resulted in its not being widely viewed as a general purpose
industrial strength technology.