As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINEERING INVESTIGATION REPORT: (EIR PT6A 2010-056) IT IS BELIEVED THAT FAILURE OF A CARRIER BOLT HEAD RESULTED IN SEIZURE OF THE POWER SECTION WHICH THEN JAMMED BETWEEN THE TEETH OF A PLANET GEAR AND THE SUN GEAR, LOCKING UP THE GEAR TRAIN. APPEARS TO BE A TORQUING ERROR OF THE BOLTS AT PREVIOUS ASSY.