Aircraft Engine Reliability Analysis Using Lower Confidence Limit Estimate Procedures

Abstract : In this thesis, a spreadsheet model was developed to compute the lower confidence limit (LCL) for the reliability of a complex weapon system using a personal computer. The LCL is an estimate of the lowest reliability a system is expected to have at a given point in time with a given level of confidence. The reliability model is based on a Weibull distribution for the system component failure times. The reliability LCL procedures has been extensively validated and determined to be quite accurate when the expected number of failures is at least 10. This model is capable of supporting LCL decisions in support of the Component Improvement Program or new weapon system procurement where reliability growth analysis is used as a decision support tool. This procedure also provides program managers and engineers with a method to perform LCL analysis and thereby reduce their dependence on contractor supplied reliability data.