Article Photos: F-35 fleet grounded after engine crack found 1/2

FILE -This undated photo provided by Northrop Grumman Corp., shows a pre-production model of the F-35 Joint Strike Fighter.  The Pentagon on Friday grounded its fleet of F-35 fighter jets after discovering a cracked engine blade in one plane. The problem was discovered during what the Pentagon called a routine inspection at Edwards Air Force Base, California, of an F-35A, the Air Force version of the sleek new plane. The Navy and the Marine Corps are buying other versions of the F-35, which is intended to replace older fighters like the Air Force F-16 and the Navy F/A-18. All versions , a total of 51 planes , were grounded Friday, Feb. 22, 2013 pending a more in-depth evaluation of the problem discovered at Edwards. None of the planes have been fielded for combat operations; all are undergoing testing.AP Photo/Northrop Grumman, File)  no sales