Members of the U.S. Air Force's source selection group raised concerns about the performance of the EADS refueling boom design during the KC-X tanker competition, according to Mark McGraw, Boeing's tanker executive.

The Air Force officials were "speaking loudly" behind closed doors in meetings about their worries, and this information found during the discovery phase of Boeing's protest of the award to Northrop Grumman/EADS is "very encouraging" support for the company's protest, McGraw told reporters during an April 3 teleconference.

McGraw says, based on Northrop Grumman documents reviewed by Boeing lawyers, that it is unclear whether EADS would reuse the boom for the Australian tanker on the U.S. tanker or use a modified design. The boom program has experienced delays and a restructuring. Northrop Grumman says the boom is the same one now on the Australian Multirole Tanker Transport and is being tested for fuel passage on an Airbus A310 test platform.

Air Force worries about the risk associated with EADS' boom performance, however, weren't included in the final assessment of scoring for the team, McGraw says. This is one reflection of how McGraw says the Air Force unfairly docked Boeing's proposal for cost and risk while ignoring potential pitfalls with the Northrop Grumman/EADS North America KC-45 design.

Boeing filed its protest March 11, and the company plans to file a fourth supplemental protest document by April 4. The supplemental filings expand what Boeing sees as evidence of its claims. During this period, Boeing's lawyers are "firewalled," and able to examine Air Force and Northrop Grumman documentation. The full extent of the documents hasn't been made public, and McGraw says he doesn't have access to it.

Despite a claim from Northrop Grumman on April 2 that the protest was "narrowed," Boeing executives say they have not relented on any of their protest points. GAO dismissed motions from Northrop Grumman and the Air Force to throw out some of Boeing's claims as untimely April 2. The Air Force said in a statement that it now "better understands" Boeing's protest and will file a new report to GAO April 16.

This will allow for a full review of the Air Force's decision to award the $35 billion program to an Airbus platform for its future refueling tanker over a Boeing 767 design. The award was announced Feb. 29.

GAO has until the end of June for its review of Boeing's claims.