Reliability Failure Analysis to Characterize Time-Directed Maintenance Inspection Interval

Reliability failure analysis is performed to implement Reliability-Centered Maintenance, RCM. RCM is implemented by Condition-based Maintenance, CBM, or Time-directed Maintenance, TDM. This paper defines the approach to characterize the time-directed inspection interval for fielded systems in sustainment. The limitation of resources available to the field engineer dictates that neither the incidence nor costs of part failure are sufficient criteria to identify which parts will be selected for transition from unscheduled repair maintenance to RCM. Application of fault tree analysis combined with failure modes, effects and criticality analysis enable a selection process that optimizes the efficiency of operating capital. The FTA and FMECA hypothesize the physical, thermal, and chemical failure mechanisms that act on the part. The hypothesized failure mechanisms are evaluated by math models and simulation to isolate the statistically significant failure mechanisms — the relevant few. Empirical investigation of the statistically significant failure mechanisms begin with nondestructive investigation of control sample parts, to include: visual, microscopic, X-ray, acoustical, and modal inspections. Small scale ‘coupon’ or ‘part’ experiments are designed and performed to model failure behavior for ambient and operational sources of stress loads using accelerated and highly accelerated life test methods. Stress testing is performed on selected test articles at specified intervals to characterize the component strength properties. Data from all tests are fit to a failure model to characterize a time-interval stress-strength frequency distribution from which the reliability functions are inferred using interference theory. The reliability and hazard functions are compared to the specified risk thre4shold to characterize the Time-Directed Maintenance Inspection Interval.Copyright © 2010 by ASME