Heather Wilson, the secretary for the US Air Force, explained to lawmakers at a House Armed Services Committee hearing on Tuesday that deliveries of the tanker had been halted again in order "to make sure that the production line is being run the way that it needs to be run." Wilson noted that the current corrective action includes officials inspecting all closed compartments.
"The Air Force again halted acceptance of new KC-46 tanker aircraft as we continue to work with Boeing to ensure that every aircraft delivered meets the highest quality and safety standards," Ann Stefanek, an Air Force spokesperson, said in a statement.
"This week our inspectors identified additional foreign object debris and areas where Boeing did not meet quality standards."
According to Stefanek, the decision to hold off on deliveries was made on March 23. She also indicated that the current issues are not linked to the tanker's design or engineering specifications.
FODs are described as being any object that does not belong in or near an aircraft, and that could result in damages to personnel or the plane. Such objects include tools or spare nuts and bolts.
At a budget hearing with the House Appropriations Subcommittee on Defense on Tuesday, Wilson said that inspectors had recently opened closed wing compartments on some of the planes, finding that some areas appeared to be better than other sections, "but they weren't what we would expect."
"That is a manufacturing discipline issue, on the line… and we saw a breakdown there," Wilson said. "We expect excellence in the manufacture of our aircraft, and we are working with Boeing on corrective action plans."
"Debris translates into safety issues," he stressed.
Boeing has so far delivered seven KC-46s to the Air Force, six of which were accepted by Kansas' McConnell Air Force Base. The seventh tanker was sent to Oklahoma's Altus AFB.
Following the Tuesday declaration, Boeing spokesperson Charles Ramey told the Air Force Times in a statement that the company is "committed to delivering FOD-free aircraft to the Air Force."
"Although we've made improvements to date, we can do better," he said, adding that the company will be conducting additional inspections to each plane and that preventative measures will be put into place.
The Air Force first confirmed on March 1 that it had paused deliveries of the tanker as a result of officials finding that tools and other debris had been left in the aircraft. That first halt in deliveries came after the first six tankers had already been delivered to McConnell AFB. The KC-46s are expected to replace the service's aging KC-135 Stratotankers.