Insights on Aircraft Programmed Depot Maintenance

This technical report describes the F-15 programmed depot maintenance (PDM) process as performed at the Warner Robins Air Logistics Center (WR-ALC) in FYs 2004-2006. WR-ALC has a sequential process that F-15s follow when undergoing PDM. The average WR-ALC F-15 PDM visit runs behind schedule. This problem was reduced in recent years, largely because planned durations became more realistic. Durations also seem longer because customers do not pick aircraft up as soon as they finish PDM. Pickup lags for F-15s based overseas are expected, because they are typically flown overseas in pairs to make more efficient use of aerial tanker refueling. However, even for continental United States-based aircraft, it was not uncommon for operators to wait a week or more to retrieve their completed F-15s. Finally, the number of days spent at specific steps in the PDM process varies considerably, and, because PDM does not have a particularly high priority, it can wait a long time for parts. This leads to aircraft moving through PDM steps out of sequence, with missing parts catching up with the aircraft when they become available, or to cannibalization, in which aircraft that recently entered PDM provide cannibalized parts for aircraft that are scheduled to leave sooner.