Boeing KC-135R / KC-135T Stratotanker
The CFM56 re-engine that kept the Stratotanker flying past its 60th birthday · First flight 1982 · In service 1984
The KC-135R came from the second, larger re-engining programme: KC-135As and some KC-135Es were fitted with CFM International CFM56 turbofans, designated F108 by the USAF, of about 96 kN each — nearly double the thrust of the original J57. The first KC-135R flew on 4 August 1982 and re-delivered aircraft reached units from July 1984 until June 2005; more than 417 were converted (the USAF counts 420). The KC-135T is the same conversion applied to 54 KC-135Qs, the tankers whose separate body tanks carried JP-7 fuel for the SR-71 Blackbird.
The new engines let the tanker offload up to 50% more fuel on a long sortie, burn 25% less fuel and cost 25% less to operate, while take-off noise fell from 126 to 99 dB. A handful of KC-135R(RT)s can themselves be refuelled in flight, and some carry Multi-Point Refueling System pods under the wings so they can refuel probe-equipped aircraft alongside the boom. The fleet is also receiving the Block 45 digital cockpit upgrade.
France re-engined its 11 surviving C-135F tankers to the same CFM standard as the C-135FR between 1985 and 1988; they served until replaced by the A330 MRTT Phénix in December 2023. Turkey flies seven KC-135Rs, Singapore operated four from 1999 to 2019, and the private company Metrea has acquired both the ex-Singapore and the ex-French aircraft. With about 375 still in USAF service in 2026, the R/T is planned to fly alongside the KC-46 until at least 2050.
