The Boeing KC-46 Pegasus is an American military aerial refueling and strategic military transport aircraft developed by Boeing from its 767 jet airliner. In February 2011, the tanker was selected by the United States Air Force (USAF) as the winner in the KC-X tanker competition to replace older Boeing KC-135 Stratotankers. The first aircraft was delivered to the USAF in January 2019.

The United States Air Force has taken delivery of 105 KC-46A aircraft and intends to procure 263 in total, a number which has grown with the cancellation of the KC-Y program and may grow further if the Next Generation Air-refueling System (NGAS) program does not develop as planned. Other nations which operate or have purchased the KC-46A include Japan and Israel.

Development

Background

In 2001, the U.S. Air Force began a procurement program to replace around 100 of its oldest KC-135E Stratotankers, and selected Boeing's KC-767. The Boeing tanker received the KC-767A designation from the United States Department of Defense in 2002 and appeared in the 2004 edition of DoD model designation report. The USAF decided to lease 100 KC-767 tankers from Boeing.

U.S. Senator John McCain and others criticized the draft leasing agreement as being wasteful and problematic. In response to protests, the USAF struck a compromise in November 2003, whereby it would purchase 80 KC-767s and lease 20 more. 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. The KC-767A contract was canceled by the DoD in January 2006.

USAF KC-X program

In 2006, the USAF released a request for proposal (RFP) for a new tanker program, KC-X, to be selected by 2007. Boeing announced it may enter a higher capability tanker based on the Boeing 777, named the KC-777 Strategic Tanker. Airbus partnered with Northrop Grumman to offer the Airbus A330 MRTT, the tanker version of the A330, which was marketed to the USAF under the designation KC-30. In January 2007, the USAF issued the KC-X Aerial Refueling Aircraft RFP, calling for 179 tankers, four system development and demonstration and 175 production, in a contract worth an estimated US$40 billion (~$ in ).Air Force Posts KC-X Request for Proposals . USAF, 30 January 2007. Northrop and EADS expressed dissatisfaction at how the RFP was structured and threatened to withdraw, leaving only Boeing in the running.Evens, Ben and Daly, Matthew (AP), "Northrop-EADS threatens to withdraw bid for US Air Force contract leaving only Boeing". Aerotech News and Review, 2 February 2007.

In February 2007, Boeing announced it was offering the KC-767 Advanced Tanker for the KC-X,Borak, D. "Boeing Unveils Air Force Tanker in $40 Billion Contract Competition" . Associated Press. 12 February 2007. stating that the KC-767 was a better fit than the KC-777 for the requirements. In April 2007, Boeing submitted its KC-767 tanker proposal to USAF."Boeing Submits KC-767 Advanced Tanker Proposal to U.S. Air Force" . Boeing, 11 April 2007. 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,"Boeing Offers KC-767 Advanced Tanker to U.S. Air Force" . Boeing, 12 February 2007. 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.

Boeing submitted its final proposal in January 2008."Boeing Submits Final KC-767 Advanced Tanker Proposal to U.S. Air Force" . Boeing, 3 January 2008. In February 2008, the DoD chose the KC-30 over the KC-767, the USAF subsequently designated it KC-45A.Butler, Amy, Fulghum, Davis A and Wall, Robert. "Northrop/EADS Clinches U.S. Refueler Deal". Aviation Week, 29 February 2008. Boeing submitted a protest to the United States Government Accountability Office (GAO) in March 2008 and waged a public relations campaign in support of their protest. In June, after USAF admissions on bidding process flaws, the GAO upheld Boeing's protest and recommended the contract be rebid. In July 2008, Defense Secretary Robert Gates announced that the USAF would reopen bidding,"Air Force to Reopen Bidding on Tanker Contract" . New York Times, 10 July 2008. and put the contract into an "expedited recompetition" with Defense Undersecretary John Young in charge of the selection process, not the USAF.Kruzel, John J. "Pentagon Reopens Bidding on Tanker Contract" . US DoD, 9 July 2008. A draft of the revised RFP was provided to contractors in August 2008 for comments."Pentagon Issues New Tanker Bid Parameters". Aviation Week, 6 August 2008. However, in September 2008, the DoD canceled the KC-X solicitation."DoD Announces Termination of KC-X Tanker Solicitation" . US DoD, 10 September 2008.

In September 2009, the USAF began a new round of bids with clearer criteria, including reducing the number of requirements from 800 to 373 in an attempt to simplify the process and allow more objective decision making. In March 2010, Boeing announced it would bid the KC-767 for the new KC-X round."Boeing to Offer NewGen Tanker to US Air Force" . Boeing, 4 March 2010. EADS stated in April 2010 it would submit a bid without Northrop Grumman as a U.S. partner."EADS Re-Enters Tanker Bidding" . Wall Street Journal, 21 April 2010.Butler, Amy. "Northrop Grumman Officially Out of KC-X". Aviation Week, 9 March 2010. 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.Warwick, Graham. "Boeing Wins Restaged U.S. Air Force KC-X Tanker". Aviation Week, 25 February 2011. Boeing submitted a revised bid in February 2011.Gates, Dominic. "Boeing, EADS Submit Final Bids For Air Force Tanker Contract" . Seattle Times, 11 February 2011.

In addition to the KC-X, observers speculate that a modified KC-46 would be used as the basis of the KC-Y tanker program, the second step of the USAF's three-step tanker renewal plan, as replacing it with something entirely new would likely be too big a risk.. Defense news, 14 September 2014 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.

Selection and early development In February 2011, the USAF announced the selection of Boeing's KC-767 bid, which was designated KC-46A."Boeing Wins $35B Air Force Tanker Deal" . Bloomberg, 24 February 2011. Boeing was awarded a development contract, which called for the delivery of 18 initial operational KC-46s by 2017. The USAF sought a total of 179 new tankers. In June 2011, development costs were reportedly projected to overrun by about $300 million (~$ in ). Boeing would be responsible for this amount, which exceeds the contract cost cap of $4.9 billion. In July 2011, revised projections indicated a reduced cost overrun.Weisgerber, Marcus. . Defense News, 27 July 2011. In 2013, the USAF added additional crews and flight hours to their future plans in response to a review that showed that the best of current plans did not take full advantage of the KC-46's cargo and aeromedical evacuation advantages over the KC-135.

In August 2013, Boeing and the USAF completed a critical design review (CDR) for the KC-46. With the CDR complete, the design was set and production and testing could proceed. Wing assembly for the first aircraft began in June 2013. Flight testing of the 767-2C airframe, which would be reconfigured into the KC-46, was scheduled to begin in mid-2014. The first fully equipped KC-46 was projected to fly in early 2015. The contract called for Boeing to build four test aircraft and deliver 18 combat-ready tankers by August 2017. The USAF intended to buy 179 KC-46s, with all delivered by 2028."US Air Force, Boeing Finalize KC-46A Tanker Aircraft Design." Boeing news release, 4 September 2013.

In December 2013, Boeing joined the wings and fuselage for the first 767-2C to be adapted into a KC-46A. The first of four 767-2C provision freighters were to complete assembly by the end of January 2014. Once assembled, it would go through ground vibration and instrumentation testing and have body fuel tanks added. The first test flight would occur during summer 2014 and include measuring its rate of climb and descent. The Engineering Manufacturing and Design (EMD) model was to be integrated with the needed systems and technologies to become a military-standard KC-46A by January 2015. Seven low-rate production KC-46s were to be delivered in 2015, 12 in 2016, and 15 delivered annually from 2017 to 2027."First KC-46A Baseline Test Aircraft Due This Month" . DoDBuzz.com, 12 January 2014 The last of four test aircraft began assembly in January 2014.

In April 2014, the GAO found that the KC-46 program was projected to underrun its projected cost estimate of $51.7 billion by $300 million. The program acquisition unit cost per jet will be $287 million, $1.8 million less than estimated. 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. In May 2014, the USAF estimated the development program's cost, including the first four aircraft, could rise from $4.4–4.9 billion to $5.85 billion.

In July 2014, Boeing recorded a $272 million pre-tax charge to cover the tanker's wiring redesign."Boeing Reports Second-Quarter Results and Raises 2014 EPS Guidance" . Boeing, 23 July 2014. The wiring issue arose when it was found that 5-10% of the wiring bundles did not have sufficient separation distance or were not properly shielded to meet a USAF requirement for double or triple-redundant wiring for some mission systems. In September 2014, it was confirmed that the wiring redesign would delay the first 767-2C flight from June 2014 to November 2014. In March 2015, the program cost to develop and procure 179 tankers was projected to total US$43.16 billion (~$ in ).

Flight tests and delays

The 767-2C's first flight took place on 28 December 2014. It flew from Paine Field and landed at Boeing Field. In March 2015, a refueling test with a C-17 transport was stopped because of a higher-than-expected boom axial load while delivering fuel. The problem was caused by the turbulent "bow wave effect" generated by two large aircraft flying in line. In January 2016, the KC-46 successfully refueled an F-16 for the first time during a five hour 36 minute sortie. Test refueling of several other military aircraft followed, including a C-17, F/A-18, A-10, and AV-8B. In February 2016, a KC-46 refueled an F/A-18, using its probe-and-drogue system for the first time.

In July 2015, Boeing announced a further $835 million (~$ in ) pretax charge for the faulty integrated fuel system's redesign and retrofit. Wiring and fuel system flaws could delay contracts worth $3 billion for up to eight months. Following schedule revisions agreed by the USAF and Boeing, the first flight of a fully equipped KC-46 was delayed to as late as September 2015. The Bank of America/Merrill Lynch noted in July 2015 "We fail to understand how Boeing could take a $1.26 billion (~$ in ) pre-tax charge (since it won the contract over Airbus) on the Boeing KC-46A program since the program is based on the 767 airframe that has been in production for over 30 years."