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NASA Reliability Preferred Practices for Design and Test
Tech Memo 4322A, Feb 1999

This site describes design and test practices that contributed to the success of NASA spaceflight missions up to year 1999. This document, "NASA Reliability Preferred Practices for Design and Test," was prepared by the NASA Reliability and Maintainability Steering Committee in February 1999. Each practice was vetted by participating NASA Centers as a valid “NASA-wide” practice. In 1998, NASA received the IEEE Reliability Society's first Company of the Year award in recognition of the publication of this document and the "Recommended Techniques for Effective Maintainability." Please note that these “preferred practices” have not been reviewed for consistency with current engineering practices. For possible updates and preferred practices (lessons learned) after 1998, use the NASA Lessons Learned Information System.

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Preferred Practices

This section contains reliability design practices provided for use throughout NASA and the aerospace community to assist in the design and development of highly reliable equipment and assemblies. The practices include recommended analysis procedures, redundancy considerations, parts selection, environmental requirements considerations, and test requirements and procedures. Each practice document defines the practice and discusses its benefits, spacecraft applications, implementation method, technical rationale, and impact of non-performance, and it also lists references and related practices.

Environmental Series

Engineering Design Series

Analysis Series

Test Series

This section contains reliability design guidelines for consideration by the aerospace community. The guidelines presented in this section contain valuable information that, in the opinion of the sponsoring activity, represents a technically credible process that could be applied to ongoing NASA programs/projects. Unlike a reliability design practice, a guideline lacks specific operational experience or data to indicate that a topic area has contributed to mission success. However, a guideline does contain information that represents current “best thinking” on a particular topic and is a well thought out approach to resolving a particular issue or problem. The Reliability and Maintainability Steering Committee agreed unanimously with the appropriateness of the approach.

Engineering Design Series

Analytical Procedures Series

Test Element Series

This section contains design and procedural practices that have contributed to successful ground support of spaceflight and ground-based aerospace programs. The information presented in this section is for use throughout NASA and the aerospace community to assist in the design, development, and operation of highly reliable ground support equipment and assemblies. This material is primarily concerned with design and test techniques, procedures for control of critical items, and control of environmental influences on successful launch.

Program Management Series

A fundamental key to program and mission success is the development of systems that are reliable and affordable to operate and maintain with today's limited resources. Early definition of both hardware and software requirements that provide the capability for rapid restoration when failures occur is essential. While incorporation of a maintainability program may require some additional early investment, the resulting benefits will include operational cost savings and improved system availability. The techniques included in this section are intended to provide management personnel with an understanding of all information necessary to develop, foster, and integrate a successful maintainability program that will enhance mission success and lower overall costs. Each technique provides high-level information on a specific subject, and can be tailored or expanded to achieve optimum application.

Design Factors and Engineering Series

Analysis and Test Series

The objective of the Maintainability function is to influence system design such that the end product can be maintained in a cost effective operational condition with minimum downtime. In order for the Maintainability discipline to provide maximum influence to a program, design principles to obtain these objectives must be implemented early in the design phase. Techniques that have proven to be beneficial on previous programs are presented in this section as design recommendations for future programs.

Operations and Operational Design Techniques

This section provides a rich source of ideas to any organization that is involved in either spaceflight operations or design to support those operations. The techniques reflect actual spaceflight operations experience and related field experience that can be used to achieve continuous improvement. They can provide a mechanism for feedback from operators of flight hardware to system designers to make the systems easier, safer, and less costly to operate. Also, they provide the design engineer with valuable information on the latest technology advances in the operations environment. These techniques also can serve as a communications tool for operations personnel, allowing for transfer of knowledge and enhancement of professional development. The techniques contained herein are the most up-to-date NASA operational processes, process improvements, and feedback to design engineers, all of which are dedicated to making NASA systems as maintainable and cost efficient as possible.