CFM International CFM-56 engine display at the Grand Forks Air Force Base (GFAFB) 'Friends And Neighbors Day' on May 27th 1989.
The CFM International CFM56 (U.S. military designation F108) series is a family of high-bypass turbofan aircraft engines, with a thrust range of 18,000 to 34,000 pounds-force.
Winning the contract to re-engine the KC-135 tanker fleet for the USAF was a huge boon to the CFM56 project (with more than 600 aircraft available to re-engine). The USAF announced the CFM56 as the winner of the re-engine contract in January 1980. Officials indicated that they were excited at the prospect of replacing the Pratt & Whitney J57 engines currently flying on the KC-135A aircraft, calling them "...the noisiest, dirtiest, [and] most fuel inefficient powerplant still flying" at the time. The re-engined aircraft was designated the KC-135R. The CFM56 brought many benefits to the KC-135, decreasing takeoff distance by as much as 3,500 feet, decreasing overall fuel usage by 25%, greatly reducing noise (24 dB lower) and lowering total life cycle cost. With those benefits in mind, the United States Navy selected the CFM56-2 to power their variant of the Boeing 707, the E-6 Mercury, in 1982. (Wikipedia)