UPDATE 1-Lockheed Martin's F-35 fighter jet grounded
October 01, 2010 at 19:09 PM EDT
WASHINGTON, Oct 1 (Reuters) - Flight testing of all three models of the F-35 fighter jet, the Pentagon's costliest arms purchase, has been suspended pending tweaks to the fuel system software, Lockheed Martin Corp , the plane's manufacturer, said on Friday.