Reliability & Maintainability Strategies For Repairable Systems In Rail Transportation Fleets

Abstract

SUMMARY & CONCLUSIONSThis paper provides a Reliability & Maintainability Strategic Decision-Making Framework Model for repairable systems in Rail Transportation Fleets. The Model is supported by, a total of 84 case studies, over a period of fifteen years, suggests that Safety is a function of Reliability. Those case studies on a large series of nonstructural repairable systems and components, impacting customer service in subway transportation fleets demonstrate that a greater proportion of the items examined exposed non-ageing related failure patterns over their in-service life-cycles. These results of In-service incursions, modeled by the use of probability distributions widely used in lifetime series analysis, revealed wear out patterns in agreement with studies in aircraft and ship fleets, as documented in Nowlan & Heap Reliability Report for UAL 1968 [1]. Remarkably, the distinctiveness of patterns which allow for the characterization of Age-Related from Non-Ageing related failure distributions provide a strategic decision making framework for component maintainability and asset configuration performance optimization within transportation operation system safety and cost. The project revealed relevant and significant truths and miss concepts in asset maintenance management reliability, such as: If an asset repair is not properly described, diagnosed and prescribed and executed, it could cause more negative impact in customer service, frustrating the expectation of a reliable performance. Also, if an asset that doesn’t expose typical age-related wear out failure distribution pattern is placed under a scheduled time-based maintenance repair or overhauls, it will not or marginally benefit from the program work; inevitably can re-introduce "infant-mortality" or premature failures. Results suggest that maintenance doesn’t improve asset reliability, it is meant to restore an item functions as close as new possible, however it is observed that there is always decay and problems of obsolescence. We argue that that results presented in this paper are a novel practical quantitative confirmation of the Reliability Centered Maintenance (RCM) [1] failure patterns in rail mass transit systems with Subway Failure Patterns in agreement with RCM and Failures in Aircrafts and Ships. The confirmation establishes a foundation for an innovative Reliability & Maintainability Strategic Decision-Making Framework Model for repairable Systems in Rail Transportation Fleets, which may further offer insights on the limitation on the application of the RCM Decision Diagram when there is no sufficient data to support an analysis. As Safety, Reliability & Maintainability are interconnected and cannot be separated; the Model can support safety analysis. With the exponential increase in technology complexity on the application of "Fault-Tolerant" & "Fail-Safe" designs, Safety is still a function of Reliability. Therefore, due to the fact we cannot completely dissociate the much close relationship between Reliability & Safety the Model proves to be profoundly essential to support the Safety Culture.