The criteria used to prevent failure of wind-tunnel models and support hardware were revised as part of a project to enhance the capabilities of cryogenic wind tunnel testing at NASA Langley Research Center. Specifically, damage-tolerance fatigue life prediction methods are now required for critical components, and material selection criteria are more general and based on laboratory test data. The suitability of two candidate model alloys (AerMet 100 and C-250 steel) was investigated by obtaining the fatigue crack growth and fracture data required for a damage-tolerance fatigue life analysis. Finally, an example is presented to illustrate the newly implemented damage tolerance analyses required of wind-tunnel model system components.Newman, John A. and Forth, Scott C. and Everett, Richard A., Jr. and Newman, James C., Jr. and Kimmel, William M.Langley Research CenterCRACK PROPAGATION; CRYOGENIC WIND TUNNELS; CRACKING (FRACTURING); TOLERANCES (MECHANICS); WIND TUNNEL MODELS; WIND TUNNEL TESTS; FATIGUE (MATERIALS); CRYOGENICS; PREDICTION ANALYSIS TECHNIQUES; MARAGING STEELS...