scope:

Purpose

The purpose of this Standard is to establish NASA structural design and test factors, as well as service life factors to be used for spaceflight hardware development and verification. The primary objective of this Standard is to define factors which ensure safe and reliable structural designs. The secondary objective is to reduce space project costs and schedules by enhancing the commonality of use of hardware designs among NASA flight projects, Centers, and their contractors. The criteria in this Standard are to be considered as minimum acceptable values unless adequate engineering risk assessment is provided that justifies the use of lower values. 

Applicability

This Standard defines engineering practices for NASA programs and projects. It may be cited in contract, program, and other Agency documents as a technical requirement. Requirements are numbered and indicated by the word "shall." Explanatory text or guidance is indicated in italics beginning in section 4. 

Tailoring of this Standard for application to a specific program or project shall be formally documented as part of program/project requirements and approved by the responsible Technical Authority. 

NASA programs and projects that do not meet the provisions of this Standard shall be assessed by the NASA Program Manager for the associated risk to the success of the planned NASA mission and approved by the responsible Technical Authority. 

This Standard shall not supersede applicable laws and regulations unless a specific exemption has been obtained by the Office of the NASA Chief Engineer.

The criteria in this Standard are applicable to launch vehicle payloads and launch vehicle structures (including propellant tanks and solid rocket motor (SRM) cases). These criteria apply to flight hardware that is utilized for NASA missions. This Standard presents acceptable minimum factors of safety for use in analytical assessment and test verification of structural adequacy of the flight hardware. Designs are generally to be verified by both structural analyses and tests.

Criteria are specified for design and test of flight articles when the actual flight hardware is tested (protoflight), and when qualification tests are conducted on a separate (prototype) article. In general, no distinction is made between "human-rated" and "robotic" missions. Structures of human-rated flight systems may be subjected to additional verification and/or safety requirements (e.g., fracture control) that are consistent with the established risk levels for mission success and flight crew safety.

Specifically excluded from this Standard are requirements for design loads determination and fracture control. Also excluded are the design and test factors for engines, rotating hardware, solid propellant, insulation, ground support equipment, and facilities. This Standard also does not cover specific configuration factors, such as fitting factors, buckling knockdown factors, and load uncertainty factors.

Constraints and Preconditions

The criteria of this Standard were developed in the context of structural and mechanical systems designs that are amenable to engineering analyses by current state-of-the-art methods and are in conformance with standard aerospace industry practices. More specifically, the designs are assumed to use materials having mechanical properties that are well characterized for the intended service environments and all design conditions. For reusable and multi-mission hardware, these criteria are applicable throughout the design service life and all of the missions.

The service environments and limit loads shall be well defined. 

Aerospace standard manufacturing and process controls shall be used in hardware fabrication and handling. 

Test hardware should, as far as is practical, be representative of the flight configuration. Deviations of the test article from the flight configuration shall be documented and approved by the responsible Technical Authority.