As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE PROPELLER SHAFT ADAPTER PLUG RETAINING RING MISSING. ADAPTER PLUG P/N 3013146 DISLODGED AND LOOSE IN THE PROPELLER SHAFT INTERNAL BORE. RETAINING RING COULD NOT BE FOUND. SUSPECT RETAINING RING HAD NOT BEEN INSTALLED. PERSONNEL/MAINTENANCE ERROR. AIRCRAFT IS REGISTERED IN PNG.