ABSTRACT
Studying about the variation of repairable systems after maintaining has always been an important work of Reliability and Maintainability and Supportability (RMS). In 1979, Mailk firstly proposed the conception of improvement factor [1], in order to describe the effect of maintenance on the failure rate of systems. In 1998, I.T. Dedopoulos and Y. Smeers [2] developed the Mailk’s theories, and put forward the age reduction factor-η, which can be use to express this effect through the age reduction of systems and has been wildly used. Nowadays, most of researchers use a stationary η so as to simplify the calculation and research [3] [4] [5]. However, the age reduction of systems is actually not stationary and will decrease with the increase of maintenance, which shows us a phenomenon of excessive repair.
