The F-22A Raptor has been designed with a service life of 8,000 flying hours, but a faulty manufacturing process discovered four months ago may cause a key structural component in 90 of the new fighters to age prematurely, officials said Monday.04-05-2006 - Marietta, Ga. -- The "forward boom frames" in the 62-foot-long fighter are constructed of titanium, a lightweight but extremely strong metal, and are used to anchor the aircraft's wings to its fuselage, said Air Force spokesman Doug Karas. During routine testing in December, Karas said, officials discovered that the titanium components may have been "improperly" treated, creating the possibility that the metal would not last as long as it is supposed to.
The flawed components, Karas said, "do not affect safety of flight and, consequently, no restrictions have been put on F-22 flight operations."
The problem affects Raptors No. 4017 through 4107, including most of the 66 Raptors that already have been delivered to the Air Force and several dozen more still being manufactured, Karas said. There are 23 Raptors assigned to Tyndall Air Force Base for F-22 pilot training with another six scheduled to arrive in the next year.
"This is not a result of improper design, but an issue with one supplier's manufacturing process," Karas said in a statement to The News Herald.
A spokesman with the Lockheed Martin Corp., prime contractor for the F-22, said Monday the company is working closely with Air Force experts to determine the extent of the problem. Structural tests including "fatigue" tests of the fuselage booms are continuing, said company spokesman Joe Quimby.
Under a "heat treat" process, the titanium boom frames are raised to a high temperature in order to "achieve the desired grain structure" in the metal, Karas said. "A section of the forward boom frames under investigation may not have been held at this temperature long enough" to reach the targeted strength, he said.
The trade publication Defense News reported Monday that it will cost about $1 billion to fix the flawed boom frames, but both Karas and Quimby flatly denied that allegation.
Raptor program officials also have identified the need to reinforce the aft boom in 41 of 73 Raptors to strengthen the juncture where the tail is attached to the fuselage, according to Air Force officials quoted by Defense News. (Of those 73 aircraft, 66 also are affected by the forward boom heat-treatment flaws, officials said.)
An Air Force spokesman told Defense News that the discovery occurred as part of the normal testing process for each new aircraft design.
"As the aircraft come down the production line, they continue to test the fleet," said Maj. Keith Scheirmann, chief of Raptor heavy maintenance and modifications at Wright-Patterson Air Force Base. "Sometimes, we find areas where we want to go back and enhance the capability or upgrade the aircraft," he told the publication.
Still, fixing the problem in each airplane could require removing the wings to inspect the boom area, a time-intensive and expensive process, officials said.
The Air Force and Lockheed Martin are conducting further tests at a company facility to determine the severity of the problems and hope to have answers by the end of May.
The Defense Department and Congress have agreed to cap the F-22 program at 183 aircraft. Lockheed Martin has contracts to build another 107 of the advanced fighters, Quimby said.