Aging Aircraft

Current United States Air Force (USAF) plans are to retain aircraft fleets for unprecedentedly long service lives, which may be as long as 80 years. The safety, aircraft availability, and cost implications of that fleet-retention policy are unknown. This study is part of Project AIR FORCE’s Aging Aircraft Project to improve the Air Force’s ability to foresee those implications and identify actions that will mitigate or avoid some of the more severe consequences, Using data from past RAND and industry reports and from various Air Force instructions and maintenance databases, and a regression analysis, it measures how the USAF aircraft fleets’ ages relate to maintenance and modification workloads and material consumption. It provides the foundation for future estimates of the effects of those activities on maintenance-resource requirements, aircraft availability, and annual operating cost. Maintenance workloads and material consumption generally exhibited late-life growth as aircraft aged, but the rate of that growth depended on both the aircraft’s flyaway cost and the workload category. For example, long-term, late-life growth was found in all base- and depot-level maintenance workloads and material-consumption categories, except phased and/or isochronal inspections, per-flying-hour contractor logistics support, and depot modification workloads. Where data were available, all workload and cost categories were affected by differences across using commands and early-life transitional events (e.g., break-in periods, early failures). Computational approaches are being developed to forecast aircraft availability from aggregate maintenance-workload data. Future work may address how planners can exploit the equations reported here to address near-term budget and resource-requirement forecasts. This report should be of interest to force planners, maintenance production planners, maintenance policy analysts, system program directors, and logistics and cost analysts.