(Updated with comments from Dunlop spokesman beginning in the 10th paragraph.)
Lockheed Martin Corp. bills the F-35 as the pinnacle of more than five decades of fighter-jet development, with the latest in stealth technology, supersonic speed, extreme agility and the most powerful sensor package available.
But someone apparently forgot to kick the tires.
Air Force Lt. Gen. Christopher Bogdan, who oversees the Defense Department's Joint Strike Fighter program, this week said some parts of the plane break down too frequently. When a reporter asked for examples, Bogdan cited a seemingly mundane component: the tires.
"Those tires today are coming off the airplane way, way, way too frequently," Bogdan said Sept. 17 at the Air Force Association's annual Air & Space Conference and Technology Exposition at National Harbor, Md.
The problem only affects the tires on the Marine Corps' version of the plane, known as the F-35B, according to Joe DellaVedova, a spokesman for the Pentagon's F-35 program office. Unlike the Air Force's F-35A or the Navy's F-35C variants, the F-35B takes off from both conventional and short runways, which puts greater stress on the tires, he said. (It can also hover and land like a helicopter onto a ship.)
“Tire wear must be improved for the F-35B variant and we have taken concrete actions to fix this problem," DellaVedova said in an e-mailed statement.
The tires on the Marine Corps' jets had a so-called initial wear rate of 10 to 11 landings per tire during testing, DellaVedova said. That rate worsened during more recent testing, which includes a higher mix of conventional take-offs and landings, he said. However, the results have improved slightly since last month's fielding of a temporary replacement tire with a thicker tread, he said.
The tires, which cost about $1,500 apiece, are made by Dunlop Aircraft Tyres Ltd., based in the United Kingdom, DellaVedova said. The company also made tires for the AV-8B Harrier jump jet, whose performance requirements are similar to those of the F-35B, he said.
Lockheed and Dunlop plan to begin delivering a redesigned product to the military by the end of the year, DellaVedova said. Bogdan, the general, said the companies will have to cover the cost of the redesign. "I'm not paying a penny," he said at the conference.
A Dunlop spokesman said the company has no record of tires "falling off" the aircraft but acknowledged there have been "some performance issues" with the initial tires.
"The F-35B faces a unique and challenging operational environment that is quite different to other variants of the aircraft," the spokesman, John Butters, said in an e-mailed statement.
"Dunlop has a long and successful history of supporting STOVL aircraft, having provided tyres for every British Harrier jet and to the US for the AV-8B and, currently, the Harriers operated by the Indian Navy," he added, referring to the acronym for short take-off and vertical landing. "We look forward to building on this with the F-35B."
The Air Force and Navy versions of the plane use a different type of tire made by Goodyear Tire & Rubber Co., DellaVedova said. That firm's products "meet specification requirements and have adequate wear characteristics," he said.
Despite the landing-gear criticism, Bogdan struck a far more conciliatory tone toward Lockheed over the development of the F-35 -- the Pentagon's most expensive weapons acquisition program. He said the relationship between the Air Force and Lockheed, along with engine-maker Pratt & Whitney, part of United Technologies Corp., is “orders of magnitude” better than it was a year ago.
“I’m encouraged by where we are today,” he said. “I’d like to be a little further along.”
The comments were a stark contrast to those Bogdan made at the same forum last year, when he called the relationship the “worst I’ve ever seen.” This year, Bogdan indicated his previous remarks were deliberate. “I threw a hand grenade into the crowd … that was intended,” he said.