By Emelie Rutherford

Boeing [BA] last week filed a seventh revision of the protest it lodged with the Government Accountability Office (GAO) in March against the Air Force’s award of the aerial refueling tanker contract to Northrop Grumman [NOC].

“We file supplementals as we discover new information that is pertinent to our protest case,” Boeing spokesman William Barksdale told Defense Daily. “Each supplemental incorporates and adds to the prior filings.”

After Boeing filed its initial protest of the tanker contract with the GAO on March 11, it quickly started filing supplemental protests. It submitted its first supplemental to the GAO March 17 and the seventh–and most recent–supplemental was filed April 16, Barksdale said.

He declined to share information on the seventh protest, saying it hasn’t been approved for release outside of a protective order yet.

Boeing has released redacted versions of its initial protest and its second supplemental protest to the public.

After releasing the second supplemental, Mark McGraw, vice president and program manager for Boeing Tanker Programs, on April 3 told reporters the company was filing updated protests after seeing materials allegedly supporting its appeal. At the time he pointed to information he said Boeing learned, subsequent to filing the initial protest, regarding the boom of the Northrop Grumman plane and the Air Force’s evaluation of the proposals’ aerial refueling and airlift capabilities.

The Air Force awarded the contract for the KC-45A aerial-refueling tanker, a pact estimated to ultimately be worth more than $35 billion, on Feb. 29 to Northrop Grumman and a team including foreign firm European Aeronautic Defense and Space Co. (EADS).

The GAO has until June 19 to render its decision on Boeing’s protest.

The Air Force gave the GAO its formal response to Boeing’s protest on April 16. The response includes “Memorandum of Law, Contracting Officer’s Statement of Facts and supporting materials,” the service said.

Barksdale said Boeing’s next step is to file its response to that Air Force report by today.

He did not rule out filing any additional supplemental protests with the GAO.

“It is possible based on new or additional information or documents produced by the Air Force, but we can’t say for certain at this time,” he said.