April 25,2008: The U.S. Air Force will retain only 41 percent of its 429 F-15C/D fighters, because of the metal fatigue detected in the air frames of many of them. The components subject to this fatigue have been identified, and it costs about $240,000 per aircraft to make the repairs. But most of the F-15C/Ds are approaching retirement age, and for many that will be moved up a bit. As a practical matter, most of these F-15s simply haven't anything to do. The only F-15s used in Iraq and Afghanistan are the two seater F-15Es, which were built more recently, are optimized for ground attack, and not affected by the metal fatigue problem. The F-22, and later the F-35, will replace the F-15.