RAND Project AIR FORCE'S long term interest in the topic of aging aircraft was rekindled in 1994, when we participated in the Air Force Scientific Advisory Board Summer Study that raised technical concerns about the viability of retaining certain aircraft past their original design lives. In 1997, the National Research Council's report on aging USAF aircraft reinforced those concerns. At that time, we initiated a modest Air Force sponsored research effort focused on emerging technical challenges for aircraft maintenance activities. Last summer we built on that technical background to examine the potential effects that aging aircraft would have on the costs of programmed depot maintenance (PDM) and engine support. The results of that work are documented in the annotated briefing that has been made available to the subcommittee. This year, we have broadened our review to cover other support and modernization activities where aircraft age may affect costs and readiness.

RAND Project AIR FORCE'S long term interest in the topic of aging aircraft was rekindled in 1994, when we participated in the Air Force Scientific Advisory Board Summer Study that raised technical concerns about the viability of retaining certain aircraft past their original design lives. In 1997, the National Research Council's report on aging USAF aircraft reinforced those concerns. At that time, we initiated a modest Air Force sponsored research effort focused on emerging technical challenges for aircraft maintenance activities. Last summer we built on that technical background to examine the potential effects that aging aircraft would have on the costs of programmed depot maintenance (PDM) and engine support. The results of that work are documented in the annotated briefing that has been made available to the subcommittee. This year, we have broadened our review to cover other support and modernization activities where aircraft age may affect costs and readiness.

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. The average WR-ALC F-15 PDM visit runs behind schedule and lasts about four months. Also, PDM can wait a long time for parts; aircraft move through PDM steps out of sequence, with missing parts catching up with the aircraft when they become available, or cannibalize other aircraft.

The U.S. Air Force is grappling with the challenge of aging fleets and the optimal time to replace them. This monograph examines commercial aviation data to draw inferences about aging aircraft that may be relevant to the Air Force. It focuses on "aging effects"-i.e., how aircraft maintenance costs change as aircraft grow older. Although commercial aircraft clearly differ from military aircraft, the aging-effect estimates might help the Air Force to project changing maintenance costs over time.