The Tanker’s Trying Time

Feb. 26, 2018

A KC-46 is loaded onto a rotating platform for testing at the Benefield Anechoic Facility at Edwards AFB, Calif. Photo: Christopher Okula/USAF

The KC-46A Pegasus tanker program ended 2017 on an upbeat note, as the first aircraft destined for operational service made its inaugural flight in early December. During the three-and-a-half-hour mission, engines, flight controls, and environmental systems were checked out. Col. John Newberry, the KC-46 system program manager, lauded the flight as “another milestone” in the program, bringing the service one step closer to fielding sorely needed new aerial refueling tankers.

The Pegasus program struggled through much of 2017, however, enduring continued delays, cost overruns, and the discovery of a serious defect.

The Air Force originally expected to accept delivery of its first operations-bound aircraft much sooner, under a deadline imposed by Boeing itself. Days before the flight, though, the company officially announced it would not meet delivery goals for 2017. This did not come as a surprise—the Air Force had already come to the same conclusion last summer.

The first hangars for Pegasus tankers are open and ready, and USAF hopes the new jets will arrive this spring.

“We will get the airplane in 2018, in my humble opinion,” Gen. Carlton D. Everhart III, commander of Air Mobility Command, said in September. “We will have a good aircraft, I believe, when we get the product. I don’t really need the aircraft right now. I need the aircraft when it’s ready.”

Last year began with a big announcement—and a big paycheck—for Boeing. In January 2017 the company received a $2.1 billion contract for the third low-rate initial production lot of 15 KC-46s. The award followed the first two lots, announced in August 2016, for seven and 12 aircraft, respectively, while the fourth lot is slated to be awarded this year.

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The 2017 contract came as the company was transitioning “from development to production” in the program, Boeing CEO Dennis A. Muilenberg told investors in an earnings call at the time and reflected no new “technical discoveries” in flight test.

The program ramped up flying operations with the first six test aircraft, flying test missions to evaluate the KC-46’s refueling system while avionics underwent ground testing at Boeing facilities in Washington state and at USAF test facilities at Edwards AFB, Calif.

Last July, a team of Boeing, Air Force, and Naval Air Systems Command officials took the Pegasus through electromagnetic testing at NAS Patuxent River, Md., aimed at evaluating its ability to fly and operate through electromagnetic fields under “mission conditions.” The jet sat on radiation pads at the Navy base, where it endured pulses from an electric coil above it.

At Edwards, a KC-46 was moved into the base’s Benefield Anechoic Facility, which is filled with polyurethane pyramids designed to stop the reflection of electromagnetic waves. The 772nd Test Squadron evaluated the aircraft’s “critically sensitive” radio systems to make sure that they would not be degraded in a real-world mission.

Test flights continued to ensure the new boom system’s compatibility with the Air Force, Navy, and Marine Corps fleets. By the end of 2017, the KC-46 had completed more than 2,000 flight hours and 1,300 hundred contacts, refueling aircraft including F-16s, F/A-18s, AV-8Bs, C-17s, A-10s, and KC-10s.

In October, two KC-46s flew together and refueled each other for the first time, off-loading the maximum fuel rate of 1,200 gallons per minute. The tankers—the first and second produced in the program—transferred a total of 38,100 pounds of fuel during the flight.

In December, the Federal Aviation Administration determined that Boeing’s 767-2C—the core configuration freighter that represents the basis of the KC-46 variant—is “safe and reliable.”

To receive this certification, Boeing had to have completed a series of tests, both on the ground and in the air, to prove the aircraft’s avionics, auto-flight, fuel system, and environmental control systems are stable. This is one of two FAA airworthiness certifications needed; another focuses on the tanker’s military systems.

The 767-2C certification is a “key building block for the KC-46 program in that it retires risk and builds confidence as we continue our test efforts,” Mike Gibbons, Boeing’s KC-46 tanker vice president and program manager, said in a statement announcing the certification.

A Pegasus undergoing tests on the electromagnetic pulse pad at NAS Patuxent River, Md., in July 2017. Photo: US Navy


Amid all the apparent progress, the Air Force offered startling news in September, announcing it had identified three “deficiencies.” One of these was considered serious, in that it could affect the tanker’s ability to refuel stealth aircraft.

Although no stealth aircraft, such as the F-22 fighter or B-2 bomber, has yet attempted to refuel from the KC-46, during some refueling test flights with other aircraft, USAF said it had observed “undetected contacts outside the receptacle.” This means the boom had touched the receiving aircraft beyond the area meant to absorb the rubbing and scraping common to air refueling. If this happened with a low-observable aircraft, the scraping could damage its special coatings, potentially ruining its stealth properties right before breaking away from the tanker to penetrate enemy airspace.

In the legacy refueling fleet—KC-135s and KC-10s—the boom operator is notified if the boom makes contact outside the refueling receptacle, Brig. Gen. Donna D. Shipton, the USAF tanker program executive officer, told reporters in September. She explained that when there is such a contact, the boom operator is required to inform the receiver aircraft pilot, who then decides whether the mission can proceed.

With the KC-46, however, the boom operator—who is positioned just behind the KC-46’s cockpit, and not at the back end of the jet where refueling is taking place—may not recognize a boom scrape when it happens, and therefore would not be able to inform the receiver pilot about a possible compromise of the receiving jet’s stealthiness.

Newberry said at the time this situation could pose “significant risk to aircrew.”

Of the other two deficiencies identified, one had to do with the high-frequency radios embedded in the wings of the KC-46. To prevent potential arcing from static electricity, the KC-46 cannot broadcast during refueling operations, but USAF testers could not tell if the radios remained turned off, and whether this potentially interfered with flight controls. USAF in February said the aircraft was still acceptable for delivery even with this deficiency, but insisted that Boeing is still required to develop a long-term fix.

The last deficiency involved an “uncommanded” boom extension while the KC-46 was on the ground. In one incident, after disconnecting, the boom struck a test stand. The apparent cause was a spike of pressure after fuel flow stopped, and such a situation is common in refueling operations, Shipton said.

The Air Force and Boeing are developing a software fix for this issue, and expect it to be resolved by the end of May, Air Force spokeswoman Maj. Emily Grabowski said.

The scraping issue is deemed far more serious, however.

“We are concerned,” Shipton acknowledged.

As of early January, the Air Force was still collecting flight test data to determine if the “deficiency rate and severity are within international air refueling standards,” Grabowski said. After this data is collected, the service will determine if it needs to make changes to the remote vision system—the 3-D camera used by the boom operator in the refueling process—or make other changes.

Higher up in the Pentagon, the issues have caused Defense Secretary Jim Mattis to say he is unwilling to accept flawed tankers.

Mattis told reporters last December, “I reinforced that the Air Force was not going to accept tankers that weren’t completely compliant with the contract.”

However, Mattis called Boeing’s efforts “excellent,” despite missing its self-imposed delivery goals, and he noted the company is working with the Air Force to resolve the scraping issue.

Costs are beginning to climb on the KC-46, along with delays, creating an unusual situation. Under the fixed-price contract, the Air Force’s costs on the program are capped at $4.9 billion, with Boeing bearing any overages.

During an October call with investors, the company reported additional costs are coming “due to incorporating changes into initial production aircraft as we progress through late-stage testing and the certification process,” Muilenberg said. The total for the third quarter of 2017 was $329 million, bringing the company’s bill for program overruns to more than $1.9 billion after taxes. Boeing hopes to make this money back through international KC-46 sales. Because of the fixed-price cost cap, US taxpayers are not responsible for the overages.

McConnell AFB, Kan., boasts this three-aircraft hangar for KC-46s. Photo: A1C Erin McClellan


Although there are no airplanes delivered yet, USAF is moving forward on its tanker plans. In mid-October, this included a ribbon cutting for an empty three-aircraft hangar at the KC-46’s first operating base, McConnell Air Force Base in Kansas.

The hangar is one of 16 projects, at a cost of $267 million, for the new aircraft. The base will eventually house 36 of the planes.

“The KC-46 will revolutionize air refueling,” Col. Joshua M. Olson, the 22nd Air Refueling Wing commander said at the ceremony. “It is only appropriate that the home of air refueling take the lead with this new airframe, and that started with these 16 construction projects. They reflect years of hard work from individuals in our community who are literally laying the foundation for the future of the Air Force.”

The KC-46’s main training base, Altus AFB, Okla., has been training Pegasus aircrew members mainly with simulators. The base also has a new flight training facility and fuselage trainer for the aircraft.

The first KC-46 Air National Guard unit will stand up in New Hampshire, and the first Air Force Reserve Pegasus unit is planned for Seymour Johnson AFB, N.C.

In January, USAF announced JB McGuire-Dix-Lakehurst, N.J., and Travis AFB, Calif., as the preferred locations for the next two Active Duty KC-46 units. The two bases are home to the Air Force’s KC-10 Extender fleet, and each will receive 24 KC-46s.

USAF plans to bring on 15 KC-46s per year at an annual cost of about $3 billion, according to its Fiscal 2018 budget request, and this rate is expected to continue through delivery of the 179th KC-46 in about 2027. But for some senior officials this pace is not fast enough.

US Transportation Command boss Gen. Darren W. McDew, testifying to Congress last March, said the current operational tempo is so high that “if we had a thousand air refueling tankers it might be enough. If you pick a spot in the world, and you bring up any kind of issue—a simultaneous or even a competing regard anywhere else in the world—your tanker[usage] rate goes up to a place that I can’t even imagine.”

The first Pegasus tanker destined for USAF takes off from the Boeing facility in Everett, Wash., on its first flight. Photo: Marian Lockhart/Boeing

The Air Force’s requirement is for 479 tankers. The Air Force has said it plans to phase out the KC-10s in 2019, but that schedule could change depending on how fast the Air Force receives KC-46s.

“We built 700 [tankers] in seven years in the ’60s,” McDew told lawmakers. If the current rate doesn’t speed up, the “plan to retire the KC-10s may be revisited.”

The Air Force is thus walking the fence between getting an operational capability fielded as quickly as possible, and getting the airplane in good working order from the outset, with all deficiencies corrected. Even with schedules changing and costs still rising, Pentagon officials are confident in the fleet airmen will eventually operate.

“We need the tankers, but I want the tankers done right,” Mattis said. “The Air Force needs tankers done right. The American taxpayer expects tankers done right, and Boeing is committed to delivering tankers that are done right. So this is a team effort, and I’m very, very comfortable that we’re on the right track. We’ll get there. It’ll be the best tanker in the world.”