WASHINGTON — The long-delayed launch of the first U.S. Air Force GPS 2F navigation satellite, now scheduled for May, could be pushed back further due to recently identified technical issues, according to a government watchdog agency.

Boeing Space and Intelligence Systems of Seal Beach, Calif., is the GPS 2F prime contractor, responsible for delivering 12 spacecraft. The program has more than doubled its original $729 million price tag and is already three-and-a-half years behind schedule.

The latest launch date for the first GPS 2F spacecraft could be in jeopardy as new, unspecified problems have arisen, according to the Government Accountability Office (GAO) report, “Defense Acquisitions — Assessments of Selected Weapons Programs.” The audit was completed in January but the report was not released until March 30.

Additional risks remain for the program, the GAO found. The current GPS 2F schedule calls for Boeing to have completed the second through sixth satellites by the time the first is launched and checked out on orbit. If problems are identified during that checkout period, the five craft may have to be modified to correct the issue, the report said. The program faces another deployment schedule challenge in that the main pad from which the satellites will be launched appears to be overbooked for 2011 and 2012, the report said.

“While numerous technical challenges have been identified and resolved, the government and contractor teams have maintained mission success as the number-one priority for this nationally-critical program,” the Air Force’s GPS program office said in response to a draft of the GAO’s report. “This focus has created cost and schedule issues for the program, but strong and creative leadership has minimized those effects to the greatest extent possible.”

Boeing did not immediately respond to a request for comment.

Meanwhile, Lockheed Martin Space Systems of Sunnyvale, Calif., is making progress early on in the development of the next-generation GPS Block 3A satellites, the GAO found. The company was awarded a $3 billion prime contract in May 2008 to build the eight GPS Block 3A satellites. The company finished the satellites’ preliminary design review in May 2009 and a critical design review is planned for October, the report said.

As of September 2009, the total program cost estimate was $3.68 billion, $164 million less than was estimated when the contract was awarded.