WASHINGTON — After spending more than $1 billion since 2002 on a Boeing-led effort to develop and produce a new generation of highly secure satellite communications terminals, the U.S. Air Force is investigating the possibility of handing that work to another contractor.

The Air Force’s Family of Advanced Beyond-line-of-sight Terminals (FAB-T) program is intended to develop several variants of ground-based and airborne satellite terminals to handle the nation’s most important and sensitive communications, including nuclear command and control. Boeing Defense, Space & Security of St. Louis has received FAB-T research and development contracts totaling at least $995 million since the program’s inception.

The Air Force is now seeking information from companies that could potentially take over as the FAB-T prime contractor, according to a June 4 posting on the Federal Business Opportunities website. The service is interested in companies that have a suitable existing terminal or could build or modify an existing terminal within two years, the posting said. Based on responses that are due June 19, the Air Force intends to hold an industry day for potential prime contractors.

Air Force spokeswoman Patty Welsh was unable to provide by press time an explanation for the service’s interest in potentially changing prime contractors.

The total projected price tag of the FAB-T program has risen by 27 percent, from $3.1 billion to $3.9 billion, in the last three years, according to an analysis completed in January by the U.S. Government Accountability Office (GAO). The Air Force has spent a total of $1.3 billion to date, and still needs $435 million in research and development funding and $2.2 billion in procurement funding to finish the program, the GAO said.

In addition to operating with the Air Force’s legacy Milstar secure communications satellites and terminals, FAB-T terminals are designed to work with the next-generation Advanced Extremely High Frequency satellites, the first of which is expected to launch in July. Under the first increment of the program, Boeing is under contract to design and produce engineering models for B-2, B-52, RC-135, E-6 and E-4 aircraft in addition to ground terminals. The first FAB-T engineering model to be delivered, for the B-2 bomber, successfully completed its first series of flight tests last summer.

The FAB-T program was previously expected to enter production in February, but plans now call for extending the development phase, the GAO said. Program officials told the GAO that only four of the six critical technologies were mature enough for production as of August 2009, and two additional engineering changes are expected to increase program costs by some $50 million.

According to James Dodd, Boeing’s director of wideband communications and radio frequency systems, a decision on whether to proceed into low-rate production is now scheduled for 2012. A decision in favor would enable operational use of the terminals to begin in late 2014, he said in a June 11 e-mailed response to questions.

This year Boeing will continue qualification testing of the hardware and development of the software.

“The program is 60 percent complete with hardware qualification and well into software qualification,” Dodd said. “We have integrated the Low Data Rate waveform and demonstrated capability at Extended Data Rate with terminal software integration well underway.”

Boeing plans to respond to the Air Force’s request for information, Dodd said.

One possible contender for the work now under contract to Boeing is Raytheon Network Centric Systems of Marlborough, Mass. Raytheon has built Milstar terminals in the past, and in May the company was awarded a $92 million Army contract for Humvee-mounted terminals for the Advanced Extremely High Frequency system. Raytheon unsuccessfully bid for the FAB-T prime contract earlier this decade and was subsequently rebuffed in its protest of the award to Boeing. Raytheon spokesman Kevin Wynn declined to comment on the company’s position with regard to the FAB-T program.