The GAO report also found costs for the estimated $44.4 billion program to purchase 179 KC-46 tankers dropped $7.3 billion from initial estimates mostly because the Air Force has not added or changed requirements.
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In recent months, Boeing had projected first deliveries in March and later August of this year before its most recent target date of December.
“They’ve been making steady progress, unfortunately it’s just been slower than they had originally planned,” said Shipton, who took over management of the Tankers Directorate in June.
The Air Force awarded Boeing an initial $4.9 billion fixed-price contract for development and production of the first 18 aircraft. Boeing has absorbed about $1.65 billion in additional costs, according to the company.
“The price was the result of a cost shootout,” said Richard Aboulafia, a senior aerospace consultant with Virginia-based Teal Group said in an email.
“Since cost overruns on the contract are paid for by Boeing, it’s a good deal for the service,” he added. “Of course, now the service also has to pay for the additional costs associated with keeping some KC-135s in service for longer than expected.”
A company spokesman said flight tests, meeting FAA certification standards, and design changes have taken time while “steady progress” was made against development headwinds.
“KC-46 remains a challenging program and we are mindful of the risks inherent in every phase of this complex aerospace development,” Boeing spokesman Charles Ramey said in an email.
Along the way, the development of the KC-46 Pegasus had encountered obstacles that slowed progress, such as work on a center line hose and drogue and wingtip aerial refueling pods systems and rewiring the aircraft.
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This year, the KC-46 completed electromagnetic effects tests and operating in hot weather conditions in Arizona, Shipton said.
Boeing agreed to offer the Air Force additional tests, training and initial support in the field at its expense because of prior delays, she said.
New plane will replace aging jets
The Air Force plans to buy 179 KC-46 tankers through 2027. Eventually, the service branch expects to replace 455 aging KC-135 Stratotankers and KC-10 Extender tankers in the fleet.
No decision has been announced if it will purchase more KC-46s aircraft or opt for a different aircraft.
The Air Force, Air National Guard and Air Force Reserve have 414 KC-135 Stratotankers, the last of where were built in 1962.
The active fleet has 59 KC-10 Extenders, which took flight in the 1980s.
Some tanker aircraft flying today could serve through 2040 or beyond, Shipton said.
“We have ongoing modernization programs to keep them up to date to fly in both the military and civil air spaces,” she said.
With an average age of 55-years-old, the Stratotanker is sent to an aircraft maintenance depot every five years, she said.
In the past three years, the number of KC-135s sent to the depot requiring major structural repairs has soared to 100 percent from 40 percent, according to the Air Force. Better inspection technology and techniques pushed the percentage up quickly, the service branch said. Those repairs include things like replacing the upper wing skin and fittings that connect the wing to the plane. For each more than half century old plane, costs are about $12 million.
The KC-46’s new capabilities will change aerial refueling, officials said.
Based on the commercial Boeing 767 airliner, an operator on the tanker uses cameras on the bottom of the plane to refuel planes. In the KC-135, an operator lays on his stomach and guides the boom into a receptacle at the top of the receiving plane. With wingtip refueling pods, the KC-46 can simultaneously refuel two Navy and Marine Corps aircraft which rely on a hose and drogue system rather than a boom, and it has enhanced covert night refueling and defensive capabilities, Shipton said.
Last year, the flying tanker refueled multiple front-line aircraft, such as the A-10 ground-attack jet, F-16 fighter plane and C-17 cargo aircraft.
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However, the Air Force has reported paint scrapes on receiver aircraft during KC-46 tests have occurred “at a higher rate than it is on legacy tankers,” according to Air Force spokeswoman Ann Stefanek. She did not have information on which aircraft were affected.
Boeing and the Air Force were working to find the cause and resolve the issue, she said in an email.
Ramey said the issue is not unique to the new tanker and happens “occasionally with all tanker aircraft and we’re trying to determine how the KC-46 rates compare with current fleet norms.”
The Boeing spokesman said more than 1,000 boom connections have been carried out with five different planes. “The testers have rated the controllability of the boom as very good, and we remain confident in the design of the boom handling system,” he said. “We’re working with the USAF to understand the concern.”
Will Ohio land the KC-46?
The Air Force has announced four of 11 expected bases where the tanker will operate.
Ohio’s Rickenbacker Air National Guard Base near Columbus was one of five finalists picked for the Air Guard bases, but has not been announced as a location.
Ohio’s two U.S. senators lobbied to bring 12 of the new tankers to Rickenbacker to replace the aging KC-135.
“Although Rickenbacker did not win the first round, making the top five in the first round signals a likelihood that Rickenbacker will be near the top of the list for three follow-on rounds of fielding,” Emmalee Kalmbach, press secretary for U.S. Sen. Rob Portman, R-Ohio, said in an email.
In 2014, Portman, U.S. Sen. Sherrod Brown, D-Ohio, and three U.S. House representatives sent a letter to then-Secretary of the Air Force Deborah Lee James lobbying to bring the refueling jets to Rickenbacker.
Both Brown and Portman are hopeful the jet will land at the central Ohio base.
“The men and women at the Rickenbacker Air Guard Base have proven time and again they are ready for any mission,” Brown said in a statement to this newspaper. “I will continue to follow any upcoming decisions closely and will continue bipartisan efforts to urge the USAF to base the KC-46 at Rickenbacker.”
A message seeking comment was left with the office of U.S. Rep. Mike Turner, R-Dayton, who is the chairman of the House Tactical Air and Land Forces subcommittee.
Thus far, the Air Force has chosen to base the KC-46 at Altus Air Force Base, Okla., McConnell AFB, Kan., Pease Air National Guard Base, N.H., and Seymour Johnson Air Force Base, N.C.