Lockheed Martin’s grounded F-35 warplane still stands a chance of wowing crowds at the Farnborough Air Show in Great Britain as engineers work to restore its safety clearance before the end of the year’s biggest aviation expo.Military chiefs and the international consortium that built the jet are “hopeful” that four planes due to appear at the U.K. event will be able to cross the Atlantic this week, U.S. Defense Undersecretary Frank Kendall said at a briefing in Farnborough. The F-35, which is built in Fort Worth, was ordered to cease flying following an engine fire on June 23 thought to have been caused by friction between blades and the cowl around them. The jet has already missed an appearance at the naming of a U.K. aircraft carrier from which it will serve, as well as the weekend’s Royal International Air Tattoo and the first day of the Farnborough show, which runs until Sunday. “We’re all disappointed,” U.S. Air Force Lieutenant General Christopher Bogdan, the F-35 program manager, said at the briefing. “We’d planned for this over the past few months and it would have been a wonderful thing to have this plane here. But we’re not giving up yet. We still have a few days left.” The engine issue comes as a setback as the U.S. pushes to expand export sales of a model built to satisfy a domestic requirement from the Air Force, Navy and Marine Corps. Lockheed Martin and engine maker Pratt & Whitney took a week to strip back the stricken plane and uncover the fire’s cause, and it’s not clear if the damage can be repaired, the partners said. Four F-35 Lightning IIs were due to make the journey to the U.K., three from the U.S. Marine Corps and one from the RAF. The jet fighters are “perched” on a high state of readiness at an air force base in Maryland awaiting any lifting of the grounding order, Bogdan said, adding that any appearance at Farnborough southwest of London would need to involve a full display, with a “B52-style flyby” not under consideration. Given the time taken to reposition the aircraft, which need refueling to cross the ocean, the planes would need to leave the U.S. well before the weekend to make the trip worthwhile, he said. On Sunday, the Pentagon’s acquisition chief said he sees no broad safety issues with the F-35 as a result of the fire.“From the evidence we have so far, we don’t see at this point what I would call systemic difficulties,” U.S. Defense Undersecretary Frank Kendall said.The F-35 has been plagued by a costly redesign, bulkhead cracks, excessive weight and delays in software. Building all 2,443 planes is projected to cost $398.6 billion, a 71 percent increase in inflation-adjusted dollars since the contract with Lockheed was signed in 2001. More than 6,000 people work directly on the F-35 program at Lockheed in Fort Worth, which employs about 13,300 overall. More than 100 F-35s have been delivered to the U.S. military.American announces engine purchaseAlso Sunday, CFM International, a joint venture between General Electric and Safran, said that American Airlines Group will order $2.6 billion of its jet engines.Fort Worth-based American will purchase 200 Leap-1A engines from CFM to power 100 Airbus A320 jets it will begin receiving in 2017, the manufacturer said in a release at the start of Farnbrough. The Leap-1A engine carries a list price of $13 million.The deal with American gives CFM a boost while dealing a blow to Pratt & Whitney, which is already fielding questions over its new geared turbofan engine. A GTF engine failed in May during ground trials for the Bombardier C Series jet, halting flight tests while the planemaker and Pratt investigate.“We are pleased with how the engine has performed during testing, and we look forward to introducing it into our fleet in 2017,” Robert Isom, American’s chief operating officer, said in a statement.American also has orders for Leap-1B engines to power 100 Boeing 737 MAX aircraft, which are also scheduled to be delivered beginning in 2017, CFM said in the release. American has been a CFM customer since 1996, and the airline’s fleet includes 375 Airbus A320 family and Boeing 737 aircraft powered by CFM56 engines, according to the engine manufacturer. This article includes material from Star-Telegram archives.