As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THIS ENGINE WAS INSTALLED NEW ON A HOMEBUILT KIT VAN RV-6 AIRCRAFT. DUIRNG CRUISE FLIGHT, THE PROPELLER BECAME LOOSE CAUSING A VIBRATION. THE FRONT CRANKSHAFT COMPRESSION PLUG OPENED AND OIL WAS ALLOWED TO FLOW OUT AROUND THE BACK OF THE PROPELLER. SUBMITTER STATED TEXTRON LYCOMING SI 1435 WAS NOT C/W WHICH WOULD HAVE ALLOWED OIL TO RETURN TO THE SUMP.