As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CRUISE SMOKE BEGAN FILLING THE CABIN. FLIGHT CONTINUED AND LANDED WITHOUT INCIDENT. MAINTENANCE INVESTIGATION FOUND #3 PROPELLER VALVE HOUSING COVER WAS CRACKED AND LEAKING OIL. FRICTION ON SLIP RINGS GENERATED SMOKE WHICH WAS INGESTED BY THE PRESSURIZATION SYSTEM. VALVE HOUSING COVER, SLIP RING AND BRUSH BLOCK REPLACED. AIRCRAFT RETURNED TO SERVICE.