Maintainability and Maintenance Approach to Orbiter ECLSS Design

On the Shuttle Program, a great deal of effort is being expended toward the end of having a reuseable flight system with a minimum of expenditure of development dollars. Because of much of the hardware which is presently both space and man rated has achieved that status on programs with non-reuseable hardware, there are significant challenges to achieving a balance between development and production costs and those costs associated with supporting the deployed system. The maintainability analysis processes are described, as well as the various figures of merit associated with this support system and the maintenance characteristics of the flight and ground hardware. The interplay between hardware maintenance analysis and the derived design requirements, for both the flight and ground hardware, are described. A distinct relationship will be developed between the packaging and installation design approaches and the instrumentation and associated data system interface. These concepts, approaches and methods are exemplified using the current Orbiter Environmental Control and Life Support System as the sample for application of the identified processes. The specifics of the application deal primarily with installation location, LRU definition and the fault recognition and isolation mechanisms. In addition, the off-vehicle considerations are explored, since the maintenance of reparable spares has such great potential leverage on life-cycle and per flight costs.