The US Air Force’s B-21 bomber passed an additional preliminary design review, service’s military deputy for the assistant secretary of the air force for acquisition says this week.

The air force conducted a PDR during the programme’s technology maturation and risk reduction phase before the service chose between Northrop Grumman and the Boeing/Lockheed team. A protest followed the contract award to Northrop in 2016 and the USAF conducted another three-day PDR, which just wrapped a few weeks ago, Lt Gen Arnold Bunch said 16 March.

“The tech maturation risk reduction phase was very valuable and we’re moving forward with detailed design at this point,” Bunch says. “We did one [PDR] before but then we had to make sure we came back after the downtime to clean up anything.”

Normally, one PDR is conducted is conducted during the technology maturation and risk reduction phase. The PDR assures hardware and software on the platform is operational. The programme then moves into the engineering, manufacturing and development phase, where a critical design review is conducted.

The USAF has been nearly mum on most aspects of the bomber contract. The service has even shrouded the price of the aircraft, arguing adversaries could gain information on the aircraft’s capabilities by working back the cost of the bomber. When asked about the programme’s timeline, Bunch told reporters he did not have the schedule off the top of his head but the programme is progressing toward detailed design and CDR.

The USAF applying lessons learned from its B-2 bomber programme to the B-21, including the way the service releases information. The air force has completely changed the way it structures the new bomber programme, with a focus on transparency and oversight from Congress, he says.

“We weren’t as transparent as we needed to be,” Bunch says of the B-2 programme. “We didn’t release information at the right times.”

But that philosophy appears to be at odds with other USAF leadership. During a recent Congressional hearing on nuclear deterrence, US Strategic Command head USAF Gen John Hyten complained that the press releases too much information on the price of strategic programmes.

“I hate the stuff that shows up in the press,” he told lawmakers. “I think we should reassess that. I hate the fact that costs us so much to open the press as well. Because if you put a cost estimate out in the press, it's not only our adversaries that are looking at it, but the people that are gonna build the system are looking at that.”

Bunch told reporters the USAF is trying to strike a balance when it comes to transparency and preventing adversaries from taking advantage of information. The service is working with the intelligence community, industry and office of the defense secretary to determine what information can be released, he adds.

“Take my willingness to be open with where we’re at today,” he says. “I don’t see releasing any more details for a period of time. We’ve been very open so far...I don’t know that I have to release anything else right now and we need to watch how we’re communicating so I’m telling you we started this with a balance.”