The Air Force and prime contractor Boeing [BA] on Sunday successfully completed the KC-46A aerial refueling tanker’s first refueling flight, according to a company statement.
Following takeoff from Boeing Field in Seattle, the KC-46A test team worked through a series of test points before offloading 1,600 pounds of fuel to a F-16 fighter aircraft flying at 20,000 feet. Boeing spokesman Charles Ramey said Monday the KC-46A can carry 212,299 pounds of fuel on board while the refueling boom, which was used in Sunday’s flight, can transfer up to 1,200 gallons of fuel per minute. The rate differs depending on the receiver aircraft, he said.
Col. Christopher Coombs, Air Force KC-46 system program manager, said in a Boeing statement that the first refueling flight kicks off the Milestone C aerial refueling demonstration, which he said is the prerequisite for an Air Force low-rate initial production (LRIP) decision to buy additional aircraft. Ramey said the Air Force has stated they expect the Milestone C decision to be made around late April. Ramey said Milestone C testing lasts until Boeing completes the refueling flights with the F-16, C-17, F/A-18, A-10, AV-8B and another KC-46. An industry source said Monday these flights will be completed in the next two months.
During the five hour, 43-minute flight, both Boeing and Air Force refueling operators accomplished multiple contacts with the F-16 that confirmed the system was ready to transfer fuel. Ramey declined to say how many contacts the tanker made with the F-16, deferring to the Air Force. The service was unable to respond to a request for comment as the federal government in Washington was closed Monday due to severe weather.
Following multiple contacts, Air Force Master Sgt. Lindsay Moon, the KC-46 air refueling operator, then “flew” the tanker’s 56-foot boom downward and waited for the F-16 to move into position before fully extending the boom into its refueling receptacle. After the KC-46 completed fuel transfer to the F-16, the system automatically turned off the pumps while Moon retracted the boom.
Not all Defense Department aircraft refuel via the boom method. While the F-16 and C-17 refuel on the boom, which is a rigid, telescoping tube inserted into the receiving aircraft, Ramey said the F/A-18 refuels using the hose and drogue system. This system uses a flexible hose that trails from the tanker aircraft, utilizing a small windsock at the end of the hose that stabilizes the hose in flight and provides a funnel for the receiving aircraft to insert a probe. Ramey said the F/A-18 will be the first aircraft refueling using the hose and drogue system, which allows fuel to be transferred at 400 gallons per minute.
Also known as EMD-2, the tanker that performed Sunday’s refueling flight made its first flight on Sept. 25 and has now completed 32 flights. The program’s first test aircraft (EMD-1), a 767-2C, has completed more than 260 flight hours since its first flight in December 2014. Ramey said tanker aircraft EMD-3, a 767-2C, and EMD-4, a KC-46 tanker, will begin flight testing in the coming months. He added EMD-4 will be the next aircraft in the air.
As part of a contract awarded in 2011 to design and develop the Air Force’s next-generation aerial refueling tankers, Boeing is building four test aircraft–two 767-2Cs and two KC-46As. If the program is approved to enter LRIP, Boeing plans to build 179 KC-46As for the Air Force.
Boeing last year took a $536 million charge due to work on the tanker’s integrated fuel system, which is the final major system to be qualified on the KC-46. Ramey said Boeing has resolved this issue by adding engineering and other staff needed to support the engineering redesign, qualification, certification and manufacturing retrofit of the fuel system.
The Air Force is supposed to take delivery of the first 18 tankers by August 2017 and the remainder of the total 179 aircraft acquisition by 2027 (Defense Daily, July 17).