Derivation of technical reliability and maintenance requirements for maximised user benefits

Reliability and maintenance are not direct customer requirements. Rather, customer requirements should be expressed in terms of the benefits reliability and maintenance can deliver. Customer requirements are generally maximisation or minimisation of scenario objectives such as safety, operational success and whole-life costs. Identification of the single technical solution that best achieves these objectives requires a structured process: (1) identify customer objectives; (2) identify full range of potential solutions and applicable scenario; (3) identify R&M linkage to customer metrics using avoid, anticipate and delay model; (4) assess and refine potential solutions; avoid premature elimination of alternatives or unsupported decisions; and.(5) identify opportunities for improvement; assess all individual opportunities to improve reliability in terms of resultant effect on objectives; and where there is no adverse effect, obviously reliability should be improved, but where there is an adverse effect on other parameters, consider combined effect on objectives. QFD is a key analysis tool, supported by FMECA, data analysis and discrete event simulation. Set-based design is a useful concept to prevent inappropriate early elimination of alternatives. The REMM tool may also be useful in linking predicted reliability with development costs.