As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN CRUISE, PILOT ATTEMPTED TO REDUCE POWER FOR MANEUVERS PRACTICE. LT ENGINE WAS UNRESPONSIVE. INSTRUCTOR IDENTIFIED LT ENGINE THROTTLE PROBLEM, ENGINE RPM WAS STABLE AT NEAR FULL POWER. RETURNED TO HOME BASE. PILOT FEATHERED AND SHUTDOWN LT ENGINE ON APPROACH. MAINTENANCE DISCOVERED LT ENGINE THROTTLE CONTROL ROD END AT FUEL CONTROL HAD SEPARATED.