 Many of the "-220" engines on Block 25 and later aircraft were upgraded from 1997 onwards to the "-220E" standard, which enhanced reliability and maintainability; unscheduled engine removals were reduced by 35%.The F100-PW-220/220E was the result of the USAF's Alternate Fighter Engine (AFE) program (colloquially known as "the Great Engine War"), which also saw the entry of General Electric as an F-16 engine provider.Its F110-GE-100 turbofan was limited by the original inlet to thrust of 25,735 lbf (114.5 kN), the Modular Common Inlet Duct allowed the F110 to achieve its maximum thrust of 28,984 lbf (128.9 kN).