Aircraft Engines: Demand Forecasting and Inventory Redistribution.

Using historical experience with J79 engines, an investigation was made of the quantitative relationships between engine age, utilization, overhaul-rate, failure-rate, and fleet age-distribution. Based upon these considerations, a new computerized method for forecasting demand for spare engines is proposed to replace present AFM 400-1 procedures. A procedure for redistributing multi-indentured stocks of repairable components and assemblies from depot to base is proposed. The procedure requires forecasts of removal rates, base-to-depot return rates, MOD-METRIC-like stock-allocation levels, repair and ship times as inputs. Whenever a stock unit becomes available at the depot or is required at a base, the procedure determines in real time a stock allocation which seeks to minimize long-run expected system backorders.