Partial failure cuts short 19th test sortie of lone F-35
Lockheed Martin has launched a planned software modification to its lone F-35 test asset, after suffering an unexpected power failure during the aircraft's 19th and most recent test flight on 3 May.
"We had some very unusual electrical transient through the airplane," says Joint Strike Fighter programme executive officer US Air Force Brig Gen Charles Davis. "All the electrics dropped offline and came back after a few milliseconds."
Lockheed confirms: "The test pilot observed a partial failure of the electrical power system. The issue required that the pilot return to base and the 45min flight was slightly shorter than planned. Although the aircraft's redundant systems worked, we wanted to recover the aircraft to investigate the fault as soon as possible."
The conventional take-off and landing aircraft - AA-1 - has been returned to its run station for an engineering review and to receive flight software update FTU-2, which Lockheed says will adjust its flight parameters following the 20h flown to date and introduce on-board prognostic health management systems. "The F-35 team does not expect any overall delays in the flight-testing programme as a result of the incident," it says.
Expected to fly around six sorties a month and to remain in use until early 2009, AA-1 has so far reached a maximum altitude of 38,000ft (11,600m) and achieved a 20° angle of attack, says Davis. "The systems that we thought were really going to give us problems have performed almost flawlessly," he told a Royal Aeronautical Society lecture in London last week. The recent fault has "given us a lot of good ideas of things we have to continue to tweak and improve for the next version of the airplane", he says.
Davis says the JSF programme's nine partner nations last month participated in the first joint executive steering board meeting, during which they approved the final software configuration for the aircraft. A critical design review for the short take-off and vertical landing F-35B will be held next month, with the first aircraft - BF-1 - expected to make its first flight in May 2008.
Davis voiced concern over a proposal by the US House Armed Services Committee to reinstate the F-35's alternate General Electric/Rolls-Royce F136 engine (Flight International, 8-14 May). "If one of the committees or Congress bring the second engine in the programme I want to make sure that they fund it adequately," he says. "I want to be able to keep the development programme intact."
Ongoing challenges facing the project include addressing weight growth in the STOVL and F-35C carrier variants and Pratt & Whitney F135 engine, and negotiating the first low-rate initial production contract, says Davis.
Source: Flight International
