risk than the near-term R&D efforts, but the potentially high payoff justifies their pursuit.
Included in Part II are descriptions of recommended near-term engineering and management tasks; assessments of current and planned research administered by the aging aircraft research program (detailed assessments are contained in the committee's interim report [NRC, 1997]); identification of near-term and long-term research opportunities in the areas of fatigue (low-cycle fatigue, high-cycle fatigue, and environmental effects), corrosion and stress corrosion cracking, and inspection and maintenance technology (nondestructive evaluation and maintenance and repair); and prioritization of recommended research.
Although the investigation of structural aging phenomena is an inherently interdisciplinary endeavor, for convenience the recommended research is presented separately for individual topical areas. Chapters 6 (fatigue), 7 (corrosion and stress corrosion cracking), and 8 (nondestructive evaluation and maintenance) describe R&D opportunities focused on the aluminum structures that dominate the current aging aircraft problems. Chapter 9 provides prioritization of the near-term and long-term research recommendations. Finally, Chapter 10 describes issues related to composite primary structures that are becoming more common on newer aircraft that represent the next generation of aging aircraft.