What was found
(CAN) SHORTLY AFTER TAKEOFF & DRING CRUISE EXCESSIVE LT RUDDER WAS AREQD TO KEEP A/C STRAIGHT. PILOT CALLED THUNDER BAY TOWER, & REPORTED RUDDER PROBLEMS & DIFFICULTY CNTLLING AIRCRAFT. PILOT REQED TO LAND WITH EMERG VEHICLES READY. A/C LANDED SAFELY & TAXIED BACK TO COLLEGE HANGAR. ON MECHANICAL INVESTIGATION, IT FOUND THAT LT RUDDER SPRING HAD BROKEN AT TORQUE TUBE END, & WAS HANGING OFF FRONT BRACKET END. (UNDER FLOOR AT PILOTS FEET) THE SPRING WAS CHANGED, RIGGING & RUDDER TRAVEL WERE CHECKED, & A/C WAS RELEASED BACK TO SERVIC E.AGE OF SPRING COULD BE A CONTRIBUTING FACTOR IN THIS CASE AS THERE IS NOT A HIGH STRESS LOAD ON THIS PART.