The Marine Corps announced today it is stepping up inspections of its Vietnam-era CH-46 helicopters after the Navy discovered a crack in a rotor component on one of its aircraft. The Marine Corps is developing the V-22 to replace its fleet of CH-46s. On Monday, the Naval Air Systems Command issued a directive calling for an inspection of the aircraft every 10 flight hours instead of the existing inspection guide of 25 flight hours, according to a Marine Corps statement...