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The application of parametric reliability analysis methods for repairable units, such as Power law process, is quite clear and straightforward for a single repairable unit. However, in practice, the analyst needs to know the reliability characteristics of units at a fleet level. The application of parametric reliability analysis methods at the fleet level, even if it is limited in scope, is quite complex. The aim of this paper is to describe the use of the power law process for multiple repairable units with differing reliability characteristics, to predict the expected number of failures at fleet level. The empirical data used in the paper are based on field data gathered during the operational life of two types of multi repairable units used in the Swedish military aircraft system FPL 37 Viggen from 1977 to 2006. The paper performs the trend test using TTT-based MIL-HDBK-189 and Laplace tests, and assesses the equality of shape-parameters for the intensity function of the power law process for multiple units. Estimation of the scale- and shape-parameters using maximum likelihood estimation is also performed. The parametric approach using power law process was found to yield relatively accurate estimations of number of failures, compared to empirical data. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to present the prerequisites for a part-out-based spares provisioning (PBSP) programme during the phase-out of an aircraft fleet. Furthermore, associated key decision criteria are identified and a framework for the phase-out management process is presented. Design/methodology/approach – Once a decision has been taken to phase-out an aircraft fleet, a number of routines for operations, maintenance and storage are affected and new tasks and functions must be introduced before initiating the actual parting-out process. A decision-making system and a management framework is needed to manage spares planning during the end-of-life phase to ensure availability at minimum cost and to ensure a manageable risk of backorders. Findings – For PBSP programme during the phase-out of an aircraft fleet to succeed and be cost-effective, a number of linked processes, tasks and decisions are required, e.g., those included in the framework proposed in this paper (see Figure 3). A successful implementation of PBSP also requires that these processes and tasks are carried out in a timely manner and that the communications between the concerned parties are prompt, clear and direct. One experience from the studied case is that close and trustful contacts and cooperation between the operator and maintenance provider(s) will greatly facilitate the process. Originality/value – Although the PBSP method is fairly commonly applied within both the military and the civilian sector, somewhat surprisingly very literature has been published on the subject. Indeed, remarkably little has been published on any aspects of maintenance during the end-of-life period. [ABSTRACT FROM AUTHOR]