The Effects of Equipment Age On Mission Critical Failure Rates: A Study of M1 Tanks

Military budget limits in the late 1990s and the timeline for the Army's next generation of weapon systems have resulted in the aging of many of the Army's fleets and projected extensions in their service lives. There is a widespread belief that the increases in fleet age will create readiness and cost problems. The Army is executing recapitalization programs to rebuild or upgrade selected weapon systems in order to retain combat capabilities and hold down maintenance costs. To aid in that effort, this research assesses the effects of age on mission-critical failure rates for M1 Abrams tanks. Results suggest that tank age is a significant predictor of M1 mission-critical failures, as are usage and location. The aging effect is estimated at a 3 to 7 percent increase in tank failures per year of age, about a doubling of the failure rate, over the first 14 years of a tank's life. The magnitude and pattern of aging effects were found to differ across tank subsystems, revealing that a distinct subset of components contributes to the aging effects. These parts are the best candidates for replacement with like components in rebuild efforts. Other components emerge as readiness and/or cost drivers, whether or not a tank is new or old, indicating the need for reliability upgrade initiatives rather than simple replacement with new parts. These findings should help quantify the value of Abrams recapitalization efforts and suggest potential subsystems to target in those efforts with regard to both rebuild and upgrade.