As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ANNUAL PRE-INSPECTION RUN-UP RAN GOOD. POST INSPECTION RUN-UP RAN ROUGH. SUSPECTED A STICKING VALVE. FURTHER INVESTIGATION REVEALED A BROKEN EXHAUST ROCKER ARM AND STUCK VALVE FOR NR 3 CYLINDER ON THE LEFT ENGINE. ALSO, NOTED IS AN APPARENT INCLUSION IN THE BROKEN ROCKER ARM.