Material selection and usage requirements are typically associated with fracture critical parts, except in the case of NFC composite or bonded parts. Because of the nature of these types of materials, additional activities are necessary for NFC in accordance with [FCR 9] 6.3.f in this NASA Technical Standard.
[FCR 22] The selection, processing, and use of materials for all fracture critical and NFC composite or bonded parts shall include the following items, which are documented directly in the FCSR or the items have pertinent documents referenced in the FCSR:
- a. Fabricate parts from materials with supplier data certifications.
- b. Select materials compatible with NASA-approved Standards and Specifications.
- c. Account for the effect of operating conditions on damage tolerance properties.
Examples of conditions that may affect damage tolerance properties are temperature, operating environment (atmosphere, corrosive media), cleaning and/or inspection agents, coatings, proof test fluids, loading spectra, time, temperature, and other environmental exposures and conditions.
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d. Design and assess with strength and damage tolerance properties that are generated by tests on samples representative of the flight hardware material, subject to either item (1) or (2) below:
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(1) Material is processed to the same thickness, material process condition, and material orientation in the part that result in the worst combination for damage tolerant assessment.
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(2) The material process condition and the material orientation are fully traceable throughout fabrication and service life. Examples of activities that may affect a metallic material process condition include: mill billet hot processes, such as forging, rolling, or other high-deformation processes; metallurgical product operations, including heat treatments; shaping operations, such as rolling, spinning, or drawing; fabrication joining processes, such as welding; and any other operations known to affect the material microstructure, strength, fracture, crack growth, or environment sensitivity properties.
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e. Derived strength and damage tolerance data obtained from NASA-approved sources. If data are lacking, data are conservatively bounded or determined by sufficient testing to assess scatter to provide averages with testing approved by the RFCB.
NASA-STD-5019A w/CHANGE 4
- f. Obtain an approved MUA for any materials not developed and qualified in accordance with the requirements of NASA-STD-6016.
- g. Include all MUAs in the FCSR.
[Rationale: The specific items related to materials selection and usage are necessary to assure the information used to assess flaw or damage sensitivity is understood and accurate throughout the service life of the hardware.]