Top Pentagon acquisition officials plan to discuss options this weekend at a meeting with executives from Lockheed Martin, the prime contractor on the $300 billion program, the military’s largest.
The meeting was prompted by an internal Pentagon report suggesting that work on the new stealth fighter, known as the F-35, had fallen so far behind schedule that it could cost up to $16.6 billion more than expected over the next five years.
Lockheed Martin has disputed that assessment, and Pentagon officials have described it as a worst case that they are determined to prevent.
The biggest cost increases would come if Lockheed Martin failed to complete the flight test program by 2013. So besides adding the money in the fiscal 2011 budget, which is now being prepared, the officials said they might buy another test plane and let Lockheed use some of the earliest operational models to help finish the testing.
The Pentagon plans to buy more than 2,400 F-35s over the next 25 years, and the Air Force, the Navy and the Marine Corps will have their own versions of the single-engine fighter. Eight allied nations are also investing in the project and could buy hundreds of planes.
President Obama and the defense secretary, Robert M. Gates, praised the F-35 as the new mainstay fighter when they persuaded Congress to halt production of the more sophisticated F-22 last summer. And Mr. Gates recently said he thought “most of the high-risk elements associated with this development program are largely behind us.”
But Pentagon and Congressional auditors have criticized the program in recent years for problems with suppliers, delays in producing the first planes and a flight test program that remains only 2 percent complete.
The latest concerns came from a special Pentagon assessment team, which includes experts on airplane production who work for an office that estimates the cost of all major Pentagon programs.
The team projected that the jet program would have a $230 million shortfall in fiscal 2011. It also warned that continuing delays in the testing could escalate into much bigger overruns by forcing Lockheed Martin to retain a larger engineering staff and fix problems on planes it had already built.
Company officials said that if the Pentagon bought another test plane, it would be the Navy version meant to fly from aircraft carriers, and it would be ready for the latter stages of the flight testing.
Daniel J. Crowley, one of Lockheed Martin’s co-managers for the project, said in an interview on Friday that the company had been building planes faster and with fewer errors in recent months. He said he believed that the company’s extensive use of computerized simulations to test various systems could also save time and help it get back on schedule by 2011.
Thomas P. Christie, a former top Pentagon testing official, said contractors had made similar assertions about the benefits of computer simulations in building earlier planes, only to find that unexpected problems cropped up in the flight tests.
He said he thought the assessment team would turn out to be correct in its estimates of the potential cost overruns.
But Geoff Morrell, Mr. Gates’s press secretary, said the Pentagon was also concerned about adding too much to the program’s budget, because that could take the pressure off Lockheed Martin to manage the program better.