Age-related maintenance versus reliability centred maintenance: a case study on aero-engines

Reliability Centred Maintenance (RCM) is a procedure carried out as part of the logistic support analysis (LSA) process and is described in the US Dep artment of Defence Military Standards (Mil Std 2173). RCM allows logisticia ns the opportunity to determine the best maintenance policy for each compon ent within a system. However, the only data that are available to carryout RCM using Mil Std 2173 are of MTBF. This implies that all the necessary mat hematical models need to be based on the exponential distribution. This is a serious drawback to the whole concept of RCM as the exponential distribut ion cannot be used to model items that fail due to wear, or any other mode that is related to their age. In this paper, a new approach to RCM is propo sed using the concepts of soft life and hard life to optimise the total mai ntenance cost. For simplicity, only one mode of failure is considered for e ach component. However, the model can be readily applied to multiple failur e modes. The proposed model is applied to find the optimal maintenance poli cies in the case of military aero-engines using Monte Carlo simulation. The case study shows a potential benefit from setting soft lives on relatively cheap components that can cause expensive, unplanned engine rejections. (C ) 2000 Elsevier Science Ltd. All rights reserved.