Joint Strike Fighter officials are refocusing the program on delivering test-ready aircraft following further delays to completing F-35s for development flight-testing.

The shift will delay the first flight of aircraft still in production by up to three months, but is expected to enable faster flight-testing to recover some of the slippage.

Aircraft were previously being flown once, then grounded for modifications to incorporate design changes resulting from analysis and testing.

“There was a lot of emphasis on first flight under past program leadership. The event became important, not the readiness [for testing],” says Doug Pearson, vice president of the F-35 integrated task force.

“When there was more work to do on the aircraft, it was added after first flight. And over time, the additions became more than we wished for,” he says. For example, aircraft BF-2 flew once in February and has been in modification since.

New JSF program executive officer Brig. Gen. David Heinz has asked Lockheed Martin to study the effect of rephasing the work to accomplish the modifications on assembly before first flight.

The ferry flight to the test center at Edwards Air Force Base in California or Naval Air Station Patuxent River in Maryland would become the new programmatic milestone. “We need to get them built, and ready to test, before they fly,” Pearson says.

Instead of flying all the development F-35s by year’s end, four of the aircraft would slip into 2010, Heinz says, but Lockheed hopes to recover some of the delay by delivering fully modified aircraft into productive flight-testing.

Aircraft BF-1, the first short takeoff and vertical landing (STOVL) F-35B, is in modification following hover-pit testing and is expected to return to flight by the end of July.

After around 12 flights from the Fort Worth, Texas, plant to verify design changes and qualify the aircraft for probe-and-drogue refueling, BF-1 is expected to ferry to Patuxent River at the end of August to begin STOVL “build down” flight-testing.