The 65-Year-Old KC-135 Will Refuel America’s B-21 Stealth Bomber Into The 2040s

The Boeing KC-135R Stratotanker registered 57-1419 is famous for being the oldest jet aircraft in US Air Force combat service. As the first two numbers of its registration indicate, the aircraft was built in 1957, although its original Pratt & Whitney J57 engines have been replaced with more modern CFM F108 turbofans. The final KC-135 was delivered to the United States Air Force in 1965, by which time Boeing had produced 732 examples for the service.