Air Force Research Laboratory
Edward A. Pohl, Chris Stewart, Justin R. Chimka, Roger Snelgrove, Manuel D. Rossetti
University of Arkansas
This project analyzes historical data to determine the parts that contribute most to aircraft downtime, determinse the demand profiles for problematic parts, explores the relationship between the fractured fleet assignment and current stocking policies, develop Stockage and Marginal Analysis models.
Rapid repair capability is a key component of weapon systems availability. Delays associated with aircraft maintenance negatively affect weapon system availability. Delays can be attributed to several factors including lack of spare parts and long lead times for replacement. To overcome the fleet readiness challenges associated with these delays, the USAF utilizes supply policies which invest significant resources to maintain certain parts in the local base supply system. Many items do not meet the criteria required to establish a stock position at the local base supply and therefore may be stored at a variety of Depot Supply locations in the United States. Failure of these items can create significant delays to the repair of the failed aircraft. Currently, the C/KC-135 fleet experiences an average of 160,000 MICAP hours per month. The MICAP data for the C/KC-135 fleet indicate that 66% of the MICAP Item Hours are attributed to Cause Code A/B. These are items that are not stocked because they are either a first time demand or they do not meet stockage policy because of their low infrequent demand characteristics. The WSSMC analysis branch has hypothesized that the fractured fleet base assignment (543 Tankers, aircraft assigned range from 6 to 52, at 38 different bases) is a key contributor to the total MICAP hours. The relationship between the fractured fleet base assignments, demand profiles, current stockage policies and total MICAP hours needs to be analyzed. Then a variety of intermittent demand forecasting techniques appropriate to this specific problem domain should be explored and their effectiveness for use on the C/KC-135 fleet determined. Using an appropriate forecasting model, new stockage levels should be determined for each of the bases. Finally, the costs associated with the recommended changes in the stockage policy must be weighed against the expected gains in Weapon System Availability.