The Air Force said there were a few items to work out, though it did not describe those publicly. The Pentagon expects to complete the final review well before the Sept. 24 date specified in the Air Force contract with Boeing.
Critical design review is the last chance for the Air Force to point out problems or make changes before Boeing begins building the first aerial-refueling tanker, part of a multibillion-dollar program to replace elderly KC-135s. The review was conducted July 8-10 at Boeing's offices in Mukilteo, not far from the Everett factory, where the tankers will be assembled.
"The efforts by the combined Boeing and Air Force team to get to this point in the program development have been tremendous," Maj. Gen. John Thompson, the program executive officer for tankers, said in an Air Force News Service release Thursday.
Last month, the jet maker loaded the 767-based tanker's first wing spar into new automated machinery in the factory. That section, however, isn't subject to potential changes.
Boeing believes final approval from the Air Force could come in the near future, Jerry Drelling, Boeing's spokesman for the tanker program, wrote in an emailed statement.
"Keeping in mind how challenging development programs can be, we are optimistic about where we are with the tanker program," he wrote.
Boeing is expected to deliver the first KC-46A to the Air Force in 2016. The Chicago-based company won the competition to supply the Air Force with aerial refueling tankers in 2011. Since then, the Air Force and Boeing have worked to determine the specifics about the tanker's build and expected performance.
The first 18 tankers are due to the Air Force by 2017 under a fixed price contract. So long as the Air Force is content with those, the Pentagon will give the OK for Boeing to supply a total of 179 KC-46As by 2027.
The 767-based tanker will replace the Air Force's KC-135 tankers, which are 50 years old on average. Boeing also supplied the KC-135s.