Some U.S. F15s never to fly again

ST. LOUIS, Jan. 11 (UPI) -- A U.S. Air Force general said as many as 160 of the country's 700 aging F-15 fighter jets would likely never fly again because of safety concerns.

At a suburban St. Louis news conference Thursday, Air Force Gen. John Corley, the head of the U.S. Air Combat Command, said manufacturing defects and time-related airframe stress meant flying some planes in the fleet was too risky, CNN reported.

"I flew these airplanes 30 years ago," Corley told the broadcaster "This is a fleet of airplanes that's 25-plus years old on average. That constant pulling and pushing and twisting has also caused fatigue."

All F-15s were grounded after an Air National Guard F-15 broke up Nov. 2 during exercises in Missouri. The pilot survived but sustained a broken arm. An investigation determined there was a flaw in one of the four main metal spines of the aircraft, which has been found in others as well, the report said.

The twin-engine, supersonic F-15 has been in service since the early 1970s and is being gradually replaced by the F-22 Raptor, the report said.