FARNBOROUGH, England -- The U.S. Defense Department on Tuesday announced it has lifted the fleet-wide grounding of the F-35 fighter jet, dramatically raising hopes that the fifth-generation stealth fighter will make its international debut here this week after all.
Flight restrictions on the Lockheed Martin Corp.-made aircraft remain in place as officials investigate the cause of an engine fire last month that significantly damaged one of the aircraft and led to the grounding, according to statement from Pentagon Press Secretary Navy Rear Adm. John Kirby. The news was first reported by Andrea Shalal of Reuters.
"Yesterday the air worthiness authorities for the U.S. Navy and U.S. Air Force approved the F-35 fleet to return to flight," he said in an e-mailed statement. "This is a limited flight clearance that includes an engine inspection regimen and a restricted flight envelope which will remain in effect until the root cause of the June 23 engine mishap is identified and corrected."
"We remain hopeful that the F-35 can make an appearance at the Farnborough airshow," Kirby added. "This information is an encouraging step, but no final decision has been made at this time."
The move comes a day after Frank Kendall, the Pentagon's top weapons buyer, and Air Force Lieutenant General Christopher Bogdan, denied reports that F-35B jump-jet variants standing by at Naval Air Station Patuxent River in Maryland would leave Tuesday for the Farnborough International Air Show, one of the world's biggest air shows taking place this week outside London.
Bogdan, however, did say the four planes on the flight line at Pax River, including three Marine Corps and one Royal Air Force aircraft, were in effect on a 24-hour alert, ready to make the transatlantic flight on moment's notice.
“The minute they are cleared, they will launch,” he said during a press conference on Monday.
The entire F-35 fleet has been grounded since July 3 following a June 23 engine fire aboard an F-35A conventional Air Force model at Eglin Air Force Base in Florida. The fire was traced to excessive rubbing of fan blades in a section of the Pratt & Whitney-made F135 engine known as the integrally bladed rotor. While subsequent inspections revealed similar rubbing in several other engines, the phenomenon was far milder than in the engine that caught fire, leading Kendall and others to conclude the problem is not systemic.
Pax River's official Facebook page on Sunday posted a comment beneath a photo of the four aircraft parked on the flight line stating, “Slated to leave Tuesday morning.” That set off media speculation that the F-35Bs would arrive at Farnborough late Tuesday in time for an appearance at the event on Wednesday.
The F-35Bs were scheduled to attend multiple events this month in the United Kingdom as part of their first public appearances abroad. Even the roughly 7-hour transatlantic trip itself would be a milestone, as the longest flight recorded by any F-35 stands at 5.8 hours.
The scheduled events included a fly-over on July 4 at Rosyth Dockyard, Scotland, as part of a naming ceremony for the new British aircraft carrier, the HMS Queen Elizabeth; a static display last week at the Royal International Air Tattoo at Royal Air Force Fairford; and an aerial demonstration this week at Farnborough. The grounding caused the aircraft to miss the first two of those events and, so far, the first two days of the Farnborough show.
The appearances were designed in part to send a message to international partners and potential buyers that the single-engine fighter has rounded the corner in terms of development. The program, which began development in the 1990s, has been plagued by design challenges, cost overruns and schedule delays.
The Joint Strike Fighter is the Pentagon's most expensive acquisition program, estimated to cost nearly $400 billion for 2,443 aircraft. Keeping the planes flying over the next half-century may cost another $1 trillion in sustainment.
Eight countries have committed to help develop the F-35, including the U.K., Italy, the Netherlands, Turkey, Canada, Australia, Denmark and Norway. Also, Israel, Japan and South Korea plan to buy production models of the aircraft. The U.K. was reportedly set to sign a contract Friday at RIAT for 14 F-35Bs for the country's first squadron, but delayed the deal presumably because of the grounding and the plane's failure to show up at the event as planned.