https://phys.org/news/2018-07-boeing-higher-tanker.html

Boeing set aside $418 million in additional funds for the KC-46 tanker, an Air Force plane that has repeatedly suffered cost overruns.

The latest cost increases were for incorporating changes into test and early-build aircraft and for additional expenses in late stage testing and certification. Boeing said it expects to deliver the first tanker to the Air Force in October.