[7][8] In December 2003, the Pentagon announced a freeze on the program over an investigation into alleged corruption that led to the jailing of one of its former procurement executives who applied to work for Boeing.

[16] The KC-767 offered for this KC-X round was based on the in-development 767-200LRF (Long Range Freighter), rather than the -200ER on which Italian and Japanese KC-767 aircraft are based,[17] differing by combining the -200ER fuselage, -300F wing, gear, cargo door and floor, -400ER digital flightdeck and flaps, uprated engines, and "sixth-generation" fly-by-wire fuel delivery boom.

[21] In June, after USAF admissions on bidding process flaws, the GAO upheld Boeing's protest and recommended the contract be rebid.

[25] In September 2009, the USAF began a new round of bids with a clearer set of criteria, including reducing the number of requirements from 800 to 373 in an attempt to simplify the process and allow a more objective decision to be made.

[28][29] Boeing submitted its KC-767 "NewGen Tanker" bid, based on the 767-200 with an improved version of the KC-10's refueling boom, and cockpit displays from the 787, in July 2010.

[34] In September 2016, Air Mobility Command stated that the follow-on KC-Y acquisition program to replace the remaining KC-135s had been abandoned in favor of further KC-46s with upgrades.

The GAO noted that delays in training air crew and maintainers could cause testing to slip 6–12 months, but stated that the program had not missed any major milestones and that the development of about 15.8 million lines of software code was progressing as planned.

[61] In July 2015, Boeing announced a further $835 million (~$1.05 billion in 2023) pretax charge for the faulty integrated fuel system's redesign and retrofit.

"[64] In March 2016, the Defense Contract Management Agency reportedly had low confidence in the August 2017 deadline, predicting the first 18 tankers' delivery to run about seven months late based on past performance and current risks, such as production delays, a new joint USAF-Boeing schedule review, and flight test uncertainties.

The GAO noted that Boeing had not obtained Federal Aviation Administration's approval for two key aerial refueling systems—the centerline drogue system and the wing aerial refueling pods, which were built without following FAA processes—Boeing projected readiness for FAA certification by July 2017, over three years late.

Boeing president and chief executive Dennis Muilenburg stated that 80% of the test points required for a positive Milestone C decision had been completed.

[69] Flight testing helped determine whether a refueling fault could be resolved by either software or hardware changes, which Boeing worked on in parallel.

[70] In May 2016, a further delay of at least six months due to technical and supply chain issues was reported, potentially requiring program re-structuring and cuts.

[72][73] In July 2016, US Defense Acquisitions Chief Frank Kendall confirmed that the tanker program office was studying the delay's cost to the USAF, and that it was entitled to consideration for losses from operating the KC-135 for longer than planned.

[74] On 8 June 2016, Boeing's defense unit CEO, Leanne Caret, reported that a modified boom would be flown shortly.

The charge reflected higher costs associated with the schedule and technical challenges, such as the boom axial load issue, delays in the certification process and concurrency between testing and initial production.

[76] The initial 18 KC-46s were equipped with the boom and centerline drogue, but not the wing-mounted wing-aerial refueling pods (WARP) needed for full contractual Required Assets Available, they were delivered separately later.

[82] In January 2018, Air Mobility Command stated that tests for final FAA certification were roughly 94 percent complete.

[89] The KC-46 Pegasus is a variant of the Boeing 767 and is a widebody, low-wing cantilever monoplane with a conventional empennage featuring a single fin and rudder.

The KC-46 uses a similar Maneuvering Characteristics Augmentation System (MCAS) to that implicated in two 737 MAX crashes; in March 2019, the USAF began reviewing KC-46 training due to this feature.

[75] In order to address the stiff boom issue, which keeps a KC-46 from refueling lightweight, thrust-limited receivers like the A-10, Boeing is replacing the current actuator with one using a pressure-flow PQ valve in the 2023 time frame.

[97] Blackouts and washouts on the displays during refueling, caused by shadows or direct sunlight are a problem that will be fixed by the RVS 2.0 upgrade along with depth perception issues via the use of new cameras and a full-color high-definition screen.

[99][100] McConnell AFB was chosen because it had low construction costs and it is in a location with a high demand for air refueling, having KC-135s based there.

[103] The two outstanding issues were inadequate boom pressure when refueling the A-10 and glare induced distortion under certain conditions in the remote vision system (RVS).

[107] In April 2019, it was confirmed that the USAF halted all deliveries on 23 March and until further notification, as loose material and debris were found in planes already delivered.

[118] In late June 2024 the USAF completed a 45 hour non-stop flight around the globe as part of Project Magellan.

[129] In February 2022, the United States and Israel signed an agreement to supply KC-46s to replace the aging fleet of Israeli tankers.

[132] In November 2022, it was reported that Italy was negotiating the purchase of six KC-46s, to be designated KC-767B locally, after deciding to forgo modernization work on the current fleet of four KC-767As.

[133][134] In July 2024, Italy "halted" the acquisition of the KC-46 due to "changed and unforeseen needs" and started the procedure to procure a new tanker, possibly from another vendor.

[140] Airbus and Boeing responded to the request for information, while Ilyushin was disqualified as the official requirement is for an aircraft with two turbofan engines.