As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW REPORTED PROPELLER NOT GOING INTO FULL FEATHER AT ENGINE SHUT DOWN. INSPECTION REVEALED THAT ALL PROP BLADES WERE FREE TO TWIST 45 DEG.+ BY HAND. THERE WERE NO EXTERNAL FAULTS VISIBLE AND THE DOME MOVED FREELY WITH THE BLADES. DETAILED INSPECTION REVEALED THAT THE FEATHER SPRING HAD SHATTERED IN MANY LOCATIONS. CAUSE OF FAILURE HAS NOT BEEN DETERMINED.