Production of early models of the F-35 Lightning II should slow down to help reduced costs after potential cracks and "hot spots" were found following testing, the U.S. military's program head says.
"The analyzed hot spots that have arisen in the last 12 months or so in the program have surprised us at the amount of change and at the cost," U.S. Vice-Admiral David Venlet said in an article posted online Thursday by AOL Defense.
"Most of them are little ones. But when you bundle them all up and package them, and look at where they are in the airplane and how hard they are to get at after you buy the jet, the cost burden of that is what sucks the wind out of your lungs," he said.
Venlet said the discovery of weaknesses in the fighter is not surprising.
"It's a fighter made out of metal and composites. You always find some hot spots and cracks and you have to go make fixes. That's normal," he said.
The aircraft, also known as the Joint Strike Fighter, is currently still in early production and testing. AOL Defence says only 18 per cent of flight-testing has been completed and fatigue testing is in initial phases.
The U.S. government has been buying small quantities of the fighter, and paying for design changes and required retrofits. A fifth batch of fighters — dubbed the Low Rate Initial Production Lot 5 contract — is under negotiation. The U.S. government is pushing Lockheed Martin, the prime contractor, to pick up part of the cost for changes in design and parts.
Slowing production now would help reduce costs of replacing parts on jets completed before testing is finalized, Venlet said.
He also indicated the future of the jet is not question, stating that the changes are not required for safety but to make the jets working lift last longer.
"The question for me is not: 'F-35 or not?'" Venlet said. "The question is, how many and how fast? I'm not questioning the ultimate inventory numbers, I'm questioning the pace that we ramp up production for us and the partners, and can we afford it?"
The United States plan to buy more than 2,400 F-35 fighters at a cost of more than $380 billion US it is expected to be the largest arms purchase in history.
Canada plans to buy 65 of the aircraft.
Earlier this month, Canadian Defence Minister Peter MacKay and U.S. Secretary of Defence Leon Panetta dismissed speculation that budget pressures will cause their countries to pull back from their F-35 jet purchases.
The Canadian Press also reported this month that delivery of the jets will spread out between 2016 and 2023, with most arriving after 2019, according to internal Defence Department figures. Canada's current fleet of 77 CF-18s is due to be retired by 2020.
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F-35 Joint Strike Fighter
FIIn this file photo taken on July 14, 2011 and released by U.S. Air Force, a USAF F-35 Lightning II joint strike fighter (JSF) aircraft soars over Destin, Fla., before landing at its new home at Eglin Air Force Base. Japan selected the Lockheed Martin F-35 stealth fighter Tuesday, Dec. 20, 2011, to replace aging jets in its air force and bolster its defense capability amid regional uncertainty. (AP Photo/U.S. Air Force, Staff Sgt. Joely Santiago)
F-35 Joint Strike Fighter
A F-35 Lightning II sits on stage during the United Kingdom F-35 Lightning II delivery ceremony on July 19, 2012 at Lockheed Martin Corporation in Fort Worth, Texas. The ceremony marked the first international delivery of an F-35 Joint Strike Fighter to a partner nation. (Photo by Tom Pennington/Getty Images)
F-35 Joint Strike Fighter
(Photo by Brendan Smialowski/Getty Images)
F-35 Joint Strike Fighter
Plane models stand outside the Lockheed Martin Corporation during the United Kingdom F-35 Lightning II Delivery Ceremony on July 19, 2012 in Fort Worth, Texas. The ceremony marked the first international delivery of an F-35 Joint Strike Fighter to a partner nation. (Photo by Tom Pennington/Getty Images)
F-35 Joint Strike Fighter
The F-35 Joint Strike Fighter jet sits in front the entrance of the Asian Aerospace 2004 show in Singapore 24 February 2004. The Asia Pacific offers one of the world's strongest prospects for defence-related spending, US aerospace giant Lockheed Martin said Tuesday as it expressed confidence in remaining a major supplier to the region's governments (AFP PHOTO/ROSLAN RAHMAN)
F-35 Joint Strike Fighter
(AFP PHOTO/CARL DE SOUZA)
F-35 Joint Strike Fighter
A Lockheed Martin's F-35 Lighning II fighter jet sits on the tarmac for static display at the Singapore Airshow in Singapore on February 12, 2012. Boeing's much-delayed 787 Dreamliner is set to star at the Singapore Airshow this week where companies touting private jets and defence hardware to the Asian market will also be out in force. (ROSLAN RAHMAN/AFP/Getty Images)
F-35 Joint Strike Fighter
(ROSLAN RAHMAN/AFP/Getty Images)
F35 JSF Take Off
F-35A Flight with External Stores
On Feb. 16, 2012, the first external weapons test mission was flown by an F-35A conventional takeoff and landing (CTOL) aircraft at Edwards Air Force Base, Calif. The F-35A is designed to carry up to 18000 pounds on 10 weapon stations featuring four weapon stations inside two weapon bays, for maximum stealth capability, and an additional three weapon stations on each wing.
F-35 Joint Strike Fighter
IN AIR, NAVAL AIR STATION PATUXENT RIVER, MD - FEBRUARY 11: (EDITORS NOTE: Image has been received by U.S. Military prior to transmission) In this image released by the U.S. Navy courtesy of Lockheed Martin, the U.S. Navy variant of the F-35 Joint Strike Fighter, the F-35C, conducts a test flight February 11, 2011 over the Chesapeake Bay. Lt. Cmdr. Eric 'Magic' Buus flew the F-35C for two hours, checking instruments that will measure structural loads on the airframe during flight maneuvers. The F-35C is distinct from the F-35A and F-35B variants with larger wing surfaces and reinforced landing gear for greater control when operating in the demanding carrier take-off and landing environment. (Photo by U.S. Navy photo courtesy Lockheed Martin via Getty Images)
F-35 First Ship Landing
Courtesy: NAVAIR/JSF Program/Lockheed Martin
F35 Hovering
F-35 Flight Test Highlights
Highlights of F-35 flight testing at NAS Patuxent River, Md., NAS Fort Worth Joint Reserve Base, and Edwards AFB, Calif.
F-35 Performs First Night Flight
The first night flight in the history of the Lockheed Martin F-35 program was completed on Jan. 19, 2012 in the skies above Edwards Air Force Base, Calif. Piloted by Lockheed Martin Test Pilot Mark Ward, AF-6, an F-35A conventional takeoff and landing (CTOL) variant, launched at 5:05 pm PST and landed after sunset at 6:22 pm
F-35 Airstart Testing
An F-35 test pilot talks about airstart testing at Edwards AFB, Calif., in early 2012.
F35 Air Show
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First Posted: 12/02/11 12:05 PM ET Updated: 12/02/11 02:56 PM ET