As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) MAIN ROTOR WAS HARD TO TURN BACKWARDS INDICATING CARBON PROBLEMS. AIRCRAFT WAS GROUND RUN AS PER MANUFACTURES RECOMENDATIONS AND RELEASED FOR SERVICE AS TURBINE HAD FREED UP. COMPANY HAD REMOVED AIRCRAFT FROM SERVICE AND RETURNED IT TO BASE. ON REMOVAL OF TURBINE (TO SEND IT IN FOR CLEANING). IT APPEARED TO HAVE PARTS OF TURBINE BLADES IN BURNER CAN SECTION.