All the oldest F-15s, which make up more than 60 percent of the fleet, were regrounded this week, a statement from the Air Force said.

The Air Force investigation, which is still under way, found "possible fleet-wide airworthiness problems," as a result of defects in metal rails that hold the F-15's fuselage together.

On Nov. 3, all 672 U.S. F-15 fighters were grounded after an F-15C assigned to the Missouri Air National Guard apparently broke apart while engaged in a mock dog fight the day before. The Air Force subsequently returned the F-15s to flight status on Nov. 21.

The Air Force seeks to replace aging F-15s, some more than 30 years old, with Lockheed Martin Corp.'s F-22 Raptor. Some of the F-15 A through D models have been flying for 23 years, according to Air Force records.

Agencies

Güncelleme Tarihi: 30 Kasım 2007, 11:53