The United States Air Force is grounding the new F-35A fighter jet less than two months after it was declared combat ready due to flaws in the coolant system, Bloomberg news reports.
According the report, the insulation in the lines that carry coolant to the combat systems and computers began crumbling.
The flaw was traced to the “use of nonconforming material for the tubing insulation and improper manufacturing processes during fabrication of the cooling lines,” F-35 spokesman Joe DellaVedova said.
The defective materials are believed to originate with one of two suppliers that provide the lines and not as a result of design issues with the aircraft.
A statement sent Friday to House and Senate defense committees said that as the insulation breaks down, chunks could become dislodged and block the lines connecting the aircraft’s wing and fuselage fuel tanks.
Such a blockage could lead to changes in pressure that “may cause structural damage to the fuel tanks,” the statement said.
So far 15 craft have been grounded, 13 in the US and two more provided to Norway. Another 42 on Lockheed Martin's production line are believed to contain the faulty lines, said Bloomberg.
Eight of the faulty planes on the production line belong to Israel. Twelve more also belong to Japan (six), Italy and Norway (three each).
Israel has so far ordered a total of 33 F-35s and will be the only country in the Middle East to have the jet, which the US military is just beginning to use after years of delays and technical problems.
The Israeli version of the F-35 "Adir" had its first test flight at the Lockheed Martin facility in Fort Worth, Texas on July 26.
The craft was declared combat ready a week later on August 2.
The Israeli Air Force said earlier this year that delivery of the first jets is scheduled for December 12 of this year. It is unclear whether this delivery date will be met.
“The extent and nature of the repairs needed are not known at this point,” Pentagon spokesman Army Major Roger Cabiness told Bloomberg. “However, it is not unreasonable to assume the repairs will require
opening the fuselage and/or wings to access the fuel tanks to replace components or make repairs, which would be very intrusive and could require extensive downtime.”
In a statement Lockheed Martin spokesman Michael Rein said that “safety is always our first consideration and Lockheed Martin is committed to resolving this issue as quickly as possible to return jets to flying status.”
With a price tag of nearly $400 billion for a total of 2,443 F-35 aircraft -- most destined for the Air Force -- the plane, built by Lockheed Martin, is the most expensive in history.
Proponents tout its radar-dodging stealth technology, supersonic speeds, close air-support capabilities, airborne agility and a massive array of sensors giving pilots unparalleled access to information.
But the program has faced numerous setbacks, including a mysterious engine fire in 2014 that led commanders to ground planes until the problem could be resolved.
Other issues have led to delays and cost overruns, including software bugs, technical glitches and even a faulty eject system that risked killing pilots who weighed less than 136 pounds (62 kilos).
The Air Force's F-35A is one of three variants of the aircraft, designed to conduct conventional landings and take offs.
The F-35B, used by the Marine Corps, is capable of short take-offs and vertical landings, and the Navy's F-35C is built for use on aircraft carriers.