helicopters, such as the UH-60 Black Hawk, composite materials make up as great as 17 percent of the airframe and rotor weight (Reddick). Harold Reddick states that, “With the advent of major helicopter composite structures R&D projects, such as the Advanced Composite Airframe Program (ACAP), and Manufacturing Methods and Technology (MM&T) projects, such as UH-60 Low Cost Composite Blade Program, it is estimated that within a few years composite materials could be applied to as much as 80% of the airframe and rotor weight of a helicopter in a production program” (Reddick). Along with this application, it is the essential obligation that sound, definitive design criteria be industrialized in order that the composite structures own high fatigue lives for economy of ownership and good damage tolerance for flight safety. Safe-life and damage-tolerant criteria are practical to all helicopter flight critical components (Reddick). Citations References Oja, Michael (2013-03-18). "Structural Design Concepts: Overview of Safe Life and Damage Tolerance". Vextec.com | Reducing Life Cycle Costs From Design To Field Service. Retrieved 2019-06-11. "Fatigue (material)", Wikipedia, 2019-06-04, retrieved 2019-06-11 Reddick, Harold. "Safe-Life and Damage-Tolerant Design Approaches for Helicopter Structures" (PDF). NASA. Retrieved June 11, 2019. See also Fail-safe Fault-tolerant design Safety engineering Damage tolerance 1945 Australian National Airways Stinson crash Design