One of the biggest causes of operational cost overruns is the failure of delivered systems to meet required reliability targets. Often early fielding to achieve a desired defense function precedes government testing on reliability; in those cases manufacturer estimates of reliability are accepted as truth. This paper describes how manufacturer reliability estimates were evaluated, using early fielding data. The manufacturer used a software failure rate estimating package and adjusted for field derating, thermal conditioning, and operating environments. This paper describes how government evaluators used failure mode analysis and Chi-Square testing on available data to evaluate the contractor methods and in some cases, determine an alternate reliability estimate.
Virginia Stouffer is a SCEA-certified cost analyst with Masters’ degrees in Economics and Electrical Engineering. She has worked for LMI since 1997 and consults in areas of feasibility, cost, analysis, and modeling. She works in the areas of aviation, defense, electronics, and environment.