US Army aviation has had its modernisation tribulations, including cancellation of the Comanche and the recent struggles with Bell's ARH, but the Apache programme looks like a model for how to renew an ageing fleet - more than once. The AH-64s have been remanufactured once, from As to Ds, and are about to go through the process again as AH-64Ds are upgraded from Block IIs to Block IIIs.
It may be easier to remanufacture a helicopter, as it does not endure the fatigue-inducing G forces on a fighter, but judging by the state of Apaches returning from Iraq for reset - refurbishment before redeployment - they take a lot of punishment from blowing sand and flying bullets. And remanufacturing has enabled Boeing to keep the Apache line open so it can now build new AH-64Ds to replace aircraft lost in combat.
The US Army has already ordered 47 new Block II "wartime replacement aircraft" - WRAs - and just posted a pre-solicitation notice for 30 additional Block III WRAs it expects to procure with war-related supplemental funding - 12 in FY08, 12 in FY09 and six in FY10. In addition, the Army plans to award Boeing a contract to reman 24 more As to Ds. That will make a total of just under 700 AH-64Ds for the US Army, and will take Apache production beyond the 30-year mark.
Don't look for a replacement any time soon...