MIL-STD-781C: A Vicious Circle

Abstract

STD-781, Repairable system, Exponen-xi local time since failure i-1, i = 1, 2, ..; x0o 0. tial distribution, Homogeneous Poisson process, Force of mor-hx(x) force of mortality of time to failure. tality, "Failure rate" hxL(xi) force of mortality of ith time between successive failures, i = 1, 2, 3, Reader AIds N(t) number of failures in (0, tl. Purpose: Tutorial E{N(t)# s-expected (mean) number of failures in (0, t]. Special math needed for explanations: Probability v(t) rate of occurrence of failures at time t.

Handbook of Reliability Engineering and Management

“…In a sense, it is not surprising that the renewal assumption is not stated, since it often is implicitly assumed. As shown in Ascher (1987), for example, Military Standard 78lC also implicitly assumed renewal during repair. The basic problem here concerns the already-mentioned mixup between the exponential BOOK REVIEWS distribution's constant "failure rate" and the only numerically equal constant "failure rate" of the HPP.…”