Design for Maintainability Principles, Modularity and Rules

Rules Concerning Modules:
• Wherever 2 components are joined is a potential future maintenance point.
The method of joining should reflect the likely frequency of replacement.
• Modularize where appropriate.
• It should not be necessary to disturb a healthy unit in order to replace a faulty
unit.
• Do not use permanent fastening techniques (adhesive fastening, riveting or
welding) where separation of components will be required for maintenance.
• Where any one of a number of acceptable alternative components can be used,
design the interface to allow any of the viable alternatives to be fitted.
• Where only one unique component should be fitted, design the interface to
defeat the attempted installation of unacceptable alternatives.
• Where component orientation is important, use a unique pattern of fixing
points, or add locating pins or baffles to prevent wrong orientation during
assembly. Design every interface so that parts can only be fitted the correct
way round.
• Adopt structured programming for software code.
• Build self-test and diagnostic routines into complex data-oriented products
and systems.