The future of the U.S. Air Force C-5 Galaxy airlifter fleet has finally been settled, after years of debate about its unreliability and the cost of fixes. All 111 aircraft will benefit from the avionics modernization program (AMP), which replaces obsolete navigation, communication and cockpit instrumentation and provides a digital architecture backbone. But only the 47 C-5B and two C-5C models will benefit from the reliability enhancement and re-engining program (RERP). This includes more than 70 modifications, the most important being replacement of the four vintage GE TF39 turbofans with commercially proven CF6-80C2 powerplants. The AMP program is well under way, but only three RERP upgrades have so far been approved because of soaring costs, according to the Air Force. These three aircraft are about two-thirds of the way through a flight-test program. Lockheed Martin disputed the Air Force estimate of $146.7 million per aircraft for the AMP and the RERP on the whole fleet, for a total cost of more than $17 billion. The Air Force now estimates that $7.7 billion will be saved by not re-engining the 62 C-5A models, which will be operated by Air National Guard and Reserve units. The total program is now expected to cost $9.8 billion. The Air Force has now dropped the idea of retiring the 30 oldest C-5As and replacing them with C-17s. This could spell the end of C-17 production, which has been supported in Congress for the last three years while uncertainty over the C-5 fleet was high.