As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) #1 ENGINE SUFFERED COMPLETE POWER LOSS WITHOUT WARNING. PROPELLER WAS FEATHERED AND AIRCRAFT RETURNED TO BASE. INVESTIGATION REVEALED THE ENGINE ACCESSORY CASE HAD DECOUPLED FROM THE POWER SECTION DRIVE. MAGNETOS AND GENERATOR REMAIN STATIONARY WHEN THE ENGINE IS MANUALLY ROTATED.