F-15 models A through D -- a total of 442 planes -- were ordered grounded by Air Combat Command,Langley Air Force Base, Va., late on Nov. 27, ACC spokesman Maj. Thomas Crosson said in an interview.

The latest problem is with cracks in the planes' metal support beams, called longerons, that run the length of the aircraft, and make up the sill on which the canopy sits, Crosson told Military.com.

The entire F-15 fleet was ordered grounded in early November after the break up and crash of a Missouri Air National Guard Eagle. The Air Force began lifting the restrictions on the fleet Nov. 19 - starting with F-15E Strike Eagles -  following aggressive inspections of the planes.

ACC called for the new groundings after metallurgical analysis of the planes suggested there could be possible cracking problems with the longerons.

Officials now are working at Warner Robins Air Force Base, Ga., to develop an inspection list that will be sent out to F-15 maintainers across the Air Force.

 

Crosson said the list should be completed in a day or two, and will include a timeframe for how long the actual inspections should take.

He could not say how long it would before the latest restrictions would be lifted from the entire fleet.