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Air Force: F-15 flaws date back 30 years

Support structure defects ground older jets.

By Times Wires
Published January 11, 2008

WASHINGTON - The Air Force will keep more than 40 percent of its older model F-15 fighter jets grounded indefinitely after discovering that critical support beams have manufacturing flaws dating back nearly 30 years that could lead to catastrophic damage to the aircraft.

Air Force officials announced Thursday that the metal beams on 162 of the fighter jets have flaws - such as being too thin, too rough or improperly cut - adding that high-stress flight over the past three decades has exposed the problem in recent months.

The discovery came only after an F-15C ripped into two large chunks on a training mission over Missouri in November, leading investigators to pore over the wreckage and order inspections of the 450 other F-15 A-D models.

The Air Force's 224 newer F-15E fighter jets do not have the same flaws and have been returned to service. This week, the Air Force returned 261 F-15 A-Ds to service after they were cleared for flight.

The Air Force is reviewing decades-old contracts to determine whether the jets' manufacturers bear responsibility for the defects, officials said Thursday.

The downed Missouri plane was built in 1980 by McDonnell Douglas Corp., which merged with Boeing Co. in 1997. Boeing officials participated in the crash investigation and helped identify the structural failure, Air Force officials said.

Patricia Frost, a spokeswoman for Boeing's F-15 business, declined to comment on the Air Force investigation of the crash.

Air Force officials said Boeing's potential liability is difficult to determine because of a complex contracting history and the age of the aircraft.

"Our question will be what was the contractual arrangement at the time and is there still residual liability," Lt. Gen. Donald Hoffman, the Air Force's top acquisition officer, said Thursday. "We have to prove that the flaw had significance."

F-15s originally were designed to last 4,000 flight hours, then were upgraded to last 8,000 flight hours. The F-15 that crashed had been flown for 6,000 flight hours.

The Air Force said the planes that remain out of service have flaws in a crucial support component called a longeron, a structural beam that serves as part of the spine of the aircraft. F-15s have four longerons around the cockpit.

Some of the longerons are too thin, or have ridges or rough surfaces that put too much stress on the structure, officials said. Some longerons diverge a small amount from design specifications, while others have larger flaws.

The Air Force expects to complete the structural analysis of the planes in about four weeks.

Gen. John Corley, the head of Air Combat Command, said it would cost about $250,000 to replace each faulty longeron. But the repairs could prove more expensive than that, and many officials question whether all of the planes should be repaired.

[Last modified January 11, 2008, 01:26:58]