KC-46A Aerial Refuelling Aircraft, based on the KC-767 refuelling aircraft, is being manufactured by Boeing under a contract with the US Air Force (USAF).
The contract calls for the manufacturing of 179 KC-46 tankers to replace the old KC-135 tankers that have been in service since 1965.
KC-46A is based on the KC-767 refuelling aircraft and is a wide-body, multi-mission aircraft capable of transporting fuel, cargo, passengers and patients.
Boeing will deliver the entire KC-46 tanker fleet by 2027. The programme is expected to generate more than 50,000 jobs and will involve about 800 suppliers.
The KC-46 tanker programme received Supplemental Type Certificate (STC) from the Federal Aviation Administration (FAA) in September 2018.
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 had also announced it may enter an even 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 being marketed to the USAF under the company name, KC-30.
In late January 2007 the USAF issued the KC-X Aerial Refueling Aircraft Request for Proposal. The RFP called for 179 (4 system development and demonstration and 175 production) tankers, in a contract worth an estimated US$40 billion. However, Northrop and EADS expressed their displeasure at how the RFP was structured and threatened to withdraw, leaving only Boeing to offer an aircraft.
On 12 February 2007, Boeing announced it was offering the KC-767 Advanced Tanker for the KC-X Tanker competition. Boeing stated that for KC-X’s requirements, the KC-767 was a better fit than the KC-777. On 11 April 2007, Boeing submitted its KC-767 tanker proposal to U.S. Air Force. The KC-767 Advanced Tanker 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 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. The KC-767 uses manual flight control, allowing unrestricted maneuverability to avoid threats anywhere in the flight envelope.
Boeing submitted the final version of its proposal on 3 January 2008. On 29 February 2008, the DoD chose the Northrop Grumman/EADS KC-30, over the KC-767. The KC-30 was subsequently designated KC-45A by the Air Force. Boeing submitted a protest to the United States Government Accountability Office on 11 March 2008 and began waging a public relations campaign in support of their protest. On 18 June, following a series of admissions by the Air Force on the flaws in the bidding process, the GAO upheld Boeing’s protest and recommended the contract be rebid. On 9 July 2008, Defense Secretary Robert Gates announced that the Air Force would reopen bidding on the tanker contract. Secretary Gates put the contract for the KC-45 into an “expedited recompetition” with Defense Undersecretary John Young in charge of the selection process instead of the Air Force. A draft of the revised RFP was provided to the contractors on 6 August 2008 for comments. By mid-August the revised RFP was to be finalized. However, on 10 September 2008, the U.S. Defense Department canceled the KC-X solicitation.
On 24 September 2009, the USAF began the first steps in the 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. On 4 March 2010, Boeing announced it would bid the KC-767 tanker for the new KC-X round. EADS announced in April 2010 it would submit a tanker bid without Northrop Grumman as a U.S. partner. Boeing submitted its KC-767 “NewGen Tanker” bid on 9 July 2010. The company submitted a revised bid on 10 February 2011.
In addition to the KC-X, observers speculate that a modified KC-46 will be used as the basis of the KC-Y tanker program, the second step of the Air Force’s three-step tanker renewal plan, as altering the KC-46 process and replacing it with something entirely new is likely too big a risk.
Details of Boeing’s KC-46 tanker aircraft programme
The contract for KC-46 tankers was awarded to Boeing in February 2011. The company announced the major suppliers to be involved in the project in June 2011 and the Integrated Baseline Review (IBR) for the programme was completed in August the same year.
Boeing also completed the system requirements review, firm configuration reviews and preliminary design review (PDR) prior to the start of assembling the first refuelling boom. The critical design review (CDR) was completed in September 2013 and the first test aircraft was rolled out in early 2014.
The first Tanker System Integration Laboratory (SIL) to support testing and reduce risk during manufacture was opened in September 2012. A total of six aircraft have been built for the KC-46 tanker test and certification programme, with the first test aircraft performing its maiden flight in September 2015.
Boeing received a $2.8bn contract from the USAF in August 2016 for the first two low-rate initial production lots of seven and 12 aircraft. A contract worth $2.1bn for the third KC-46 tanker production lot of 15 aircraft and spare parts was awarded in January 2017. The USAF awarded a $2.9bn contract to Boeing for the fourth production lot of 18 KC-46A tanker aircraft.
KC-46A’s maiden flight was conducted in December 2017 and the receiver certification testing of the aircraft began in April 2018. Phase II receiver certification flight testing was completed in December 2018, while the phase III testing is scheduled for 2019.
The flight tests required for the delivery of the first KC-46 tanker were completed by the US Air Force in July 2018.
Boeing secured a $2.9bn contract from the USAF in September 2018 for the delivery of 18 additional KC-46 tanker aircraft, increasing the total to 52.
The Japan Air Self-Defense Force placed a $279m order with Boeing for the delivery of a KC-46 tanker and logistics support in December 2017. An option was exercised by the USAF for the sale of a second KC-46 tanker to the Japan Air Self-Defense Force under foreign military sale (FMS) programme in December 2018.
The USAF has taken delivery of five KC-46A tanker aircraft as of February 2019.
KC-46A aerial refuelling method
KC-46 has a maximum fuel capacity of 212,000lb. The aircraft is fitted with a flush-mounted air-to-air refuelling receptacle capable of accepting fuel at 1,200gal/min.
The refuelling systems also include a digital fly-by-wire boom capable of offloading fuel at 1,200gal/min, as well as a permanent centreline drogue system and removable wing air refuelling pods that can offload fuel at 400gal/min each.
Refuelling systems aboard the KC-46 can be managed by boom operators from the crew compartment featuring an Aerial Refuelling Operator Station (AROS). Cameras are placed at the fuselage to provide a full view of the field.
The fly-by-wire boom system enables the boom operator to refuel all fixed-wing receiver aircraft irrespective of time and mission, and also be capable of carrying out simultaneous multipoint refuelling through the wing air refuelling pods.
KC-46A aerial refuelling aircraft design
KC-46A is based on KC-767 but modifications were made to the airframe by incorporating a cargo door and an advanced flight deck display. The airframe is militarised with air refuelling capabilities, an air refuelling operator station and threat detection and avoidance systems.
The tanker is capable of carrying 18 cargo pallets, as well as transporting 58 passengers normally and up to 114 passengers during contingency operations. The tanker aircraft also provides urgent aeromedical evacuation by transporting 54 medical patients. The maximum takeoff weight of the tanker aircraft will be 415,000lb (188,241kg).
KC-46A cockpit, engines and performance
KC-46 is capable of accommodating three main crew members, including two pilots and a boom operator with capacity for 12 additional crew members.
The aircraft features an integrated display system featuring diagonal crystal displays, a tactical situational awareness system (TSAC) and a remote vision system (RVS) combining both 3D and 2D technology for the boom operator. It is also equipped with communications, navigation, surveillance, networking and flight control systems provided by Rockwell Collins.
The mission control system is supplied by GE Aviation Systems, while the onboard auxiliary power unit, cabin pressure control system and air data inertial navigation systems were provided by Honeywell. Northrop Grumman supplied the infrared countermeasures system for the aircraft.
Each USAF KC-46A tanker is powered by two Pratt & Whitney PW4062 engines, with each delivering 62,000lb (289.13kN) of thrust. Each PW4062 engine has a fan-blade diameter of 94in.
KC-46A is capable of flying at a maximum speed of 915km/h and the maximum air speed is 851km/h. The range and service ceiling of the aircraft are 12,200km and 12,200m, respectively. The aircraft weighs about 94,198kg and its maximum take-off weight will be 188,241kg
|Crew||3 (2 pilots, 1 boom operator) basic crew; 15 permanent seats for additional/optional air crew members, including aeromedical evacuation crew members|
|Capacity||seating for up to 114 people, 18 463L pallets, or 58 patients (24 litters, 34 ambulatory)|
|Payload||65,000 lb (29,500 kg)|
|Length||165 ft 6 in (50.5 m)|
|Wingspan||157 ft 8 in (48.1 m)|
|Heigh||52 ft 1 in (15.9 m)|
|Empty weight||181,610 lb (82,377 kg)|
|Max take off weight||415,000 lb (188,240 kg)|
|Power plant (Dry thrust)||2 × Pratt & Whitney PW4062 turbofan, 62,000 lbf (275.8 kN) each|
|Power plant (Thrust with afterburner)|
|Maximum speed (Sea level)|
|Maximum speed (High altitude)||Mach 0.86 (570 mph, 914 km/h)|
|Combat radius||6,385 nmi (11,830 km) ; global with in flight refueling|
|Service ceiling||40,100 ft (12,200 m)|
|Rate of climb|
|Design load factor|
- Israeli Air Force – 8 aircraft on order.
- Italian Air Force – 4 KC-46 in service.
- Japan Air Self-Defense Force – 4 aircraft on order.
- United States Air Force – 40 KC-46 in service, 179 KC-46 planed.