As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DEPARTURE, LEVELED OFF AT 7500. LEFT ENGINE RPM STARTED TO DECREASE. TORQUE, NG AND ITT REMAINED STEADY. PERFORMED A PRECAUTIONARY SHUTDOWN AND SECURED THE ENGINE. DECIDED TO RELIGHT THE ENGINE. AFTER RELIGHT, THE ENGINE WAS NORMAL FOR 5 SECONDS AT WHICH TIME RPM BEGAN TO DECREASE AGAIN. ENGINE SHUTDOWN AND SECURED ONCE AGAIN. FLEW BACK TO DEPARTURE AND DECLARED AN EMERGENCY. LANDED WITHOUT FURTHER INCIDENT.