What was found
(CAN) DURING CRUISE FLIGHT, THE CREW GOT A HYDRAULICS ISOLATION VALVE CAUTION LIGHT. THE NR 2 HYDRAULIC SYSTEM SHOWED A QUANTITY OF ONLY 1 QUART OF FLUID REMAINING. THE AIRCRAFT RETURNED TO THE POINT OF DEPARTURE AND MADE A SAFE LANDING AFTER MAKING AN ALTERNATE LANDING GEAR EXTENSION. MAINTENANCE DETERMINED THAT 2 BOLTS HAD SHEARED AT THE STEERING MANIFOLD PRESSURE INLET, CAUSING THE COVER TO BECOME DISPLACED, WHICH ALLOWED THE LOSS OF ALL THE NR 2 HYDRAULIC SYSTEM FLUID.