Page 19 - Intro Predictive Maintenance

10 An Introduction to Predictive Maintenance

design airplanes that were failure tolerant. Practices such as the replication
of system functions, the use of multiple engines, and the design of damage-
tolerant structures greatly weakened the relationship between safety and
reliability, although this relationship has not been eliminated altogether.

Mobray points to two examples of successful application of RCM in the commercial
aircraft industry—the Douglas DC-10 and the Boeing 747. When his book was
written, both of these aircraft were viewed as exceptionally reliable; however, history
has changed this view. The DC-10 has the worst accident record of any aircraft used
in commercial aviation; it has proven to be chronically unreliable. The Boeing 747
has faired better, but has had several accidents that were directly caused by reliabil-
ity problems.

Not until the early 1980s did predictive maintenance technologies, such as micro-
processor-based vibration analysis, provide an accurate means of early detection of
incipient problems. With the advent of these new technologies, most of the founding
premises of RCM disappeared. The ability to detect the slightest deviation from
optimum operating condition of critical plant systems provides the means to prevent
deterioration that ultimately results in failure of these systems. If prompt corrective
action is taken, it effectively stops the degradation and prevents the failure that is the
heart of the P-F curve.

1.2 OPTIMIZING PREDICTIVE MAINTENANCE
Too many of the predictive maintenance programs that have been implemented have
failed to generate measurable benefits. These failures have not been caused by tech-
nology limitation, but rather by the failure to make the necessary changes in the work-
place that would permit maximum utilization of these predictive tools. As a minimum,
the following proactive steps can eliminate these restrictions and as a result help gain
maximum benefits from the predictive maintenance program.

1.2.1 Culture Change
The first change that must take place is to change the perception that predictive tech-
nologies are exclusively a maintenance management or breakdown prevention tool.
This change must take place at the corporate level and permeate throughout the plant
organization. This task may sound simple, but changing corporate attitude toward or
perception of maintenance and predictive maintenance is difficult. Because most
corporate-level managers have little or no knowledge or understanding of mainte-
nance—or even the need for maintenance—convincing them that a broader use of pre-
dictive technologies is necessary is extremely difficult. In their myopic view,
breakdowns and unscheduled delays are solely a maintenance issue. They cannot
understand that most of these failures are the result of nonmaintenance issues.

From studies of equipment reliability problems conducted over the past 30 years,
maintenance is responsible for about 17 percent of production interruptions and quality