Since last October, a joint Defense Department task force has been painstakingly examining scores of military aircraft and weapons to see if certain aluminum parts are defective, according to sources and documents. The parts may have been improperly heat-treated by a California company that supplied them to military contractors during the 1980s and 1990s, according to the Defense Department inspector general. A spokesman for the Air Force Materiel Command, which is in charge of the task force, told InsideDefense.Com on...