Application of the Weibull distribution to the Cost Effectiveness Analysis Spreadsheet Model (CEAMOD) for the Aircraft Engine Component Improvement Program (CIP)

Abstract

This thesis explores the application of the Weibull distribution to the Cost Effectiveness Analysis Spreadsheet Model (CEAMOD) for the Aircraft Engine Component Improvement Program (CIP). The current model assumes the exponential distribution for all unscheduled failures. This thesis explores whether the Weibull distribution can be used in the CEAMOD. This process is performed through the use of a simulation program and spreadsheet analysis. The thesis first examines past concerns that the use of the Weibull will create cyclic annual numbers of failures of a component over an engine's life. It then examines the empirical distributions of the number of failures per year generated from simulations for a range of Weibull parameters and compares these with the Poisson distribution resulting from the current CEAMOD assumption of exponential times between failures. Finally, it considers how life cycle costs considered by the CEAMOD will change if the Weibull distribution is assumed. The conclusion is that the nature of the distribution of the annual number of failures should be studied further before the Weibull is incorporated in the CEAMOD.