(Reuters) – U.S. military officials have approved limited flights of Lockheed Martin‘s F-35 fighter jets after a nearly month-long grounding, but scrapped plans for the new U.S. warplane’s much-anticipated international debut in Britain.

The F-35, the world’s most expensive weapons project with a price tag of about $400 billion, has been largely grounded since the massive failure of a Pratt & Whitney engine on a U.S. Air Force F-35 plane at a Florida air base on June 23.

Pentagon spokesman Rear Admiral John Kirby said on Tuesday U.S. Air Force and Navy officials had granted the radar-evading jet a limited flight clearance that required engine inspections every three hours and various flight restrictions.

Later in the day, Kirby told reporters the jet would not be heading to the Farnborough air show.

“I can confirm that the Department of Defense in concert with our partners in the UK has decided not to send Marine Corps and UK F-35B aircraft across the Atlantic to participate in the Farnborough air show,” Kirby said.

“While we’re disappointed that we’re not going to be able to participate in the air show, we remain fully committed to the program itself and look forward to future opportunities to showcase its capabilities to allies and to partners.”

The jet’s failure to appear at a big military air show in Britain last week and its absence from the Farnborough event in southern England have been a blow for U.S. officials and their international partners, who were hoping to highlight the jet’s advanced capabilities before potential buyers.

Global orders for the F-35 are expected to exceed 3,000, with Italy, Turkey, Australia and Norway among the U.S. allies planning to purchase the plane.

“It’s a black eye and a PR nightmare, but it’s not going to change the outcome,” said aerospace analyst Richard Aboulafia with the Virginia-based Teal Group.

He said the jet’s absence from the British show, which began on Monday, was unlikely to affect buying decisions by foreign military forces but could prompt Canada and Denmark to opt for a competition instead of an outright F-35 purchase.

The reactions of Lockheed and Pratt & Whitney were muted.

“While we were looking forward to the F-35 demonstration at Farnborough, we understand and support the DoD and UK Ministry of Defense’s decision,” spokeswoman Laura Siebert said.

Pratt said it respected the decision, and had worked closely with the military to resume F-35 flights.

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