As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) "STRANGE" VIBRATION WAS NOTICED BY THE PILOT IN FLIGHT ALONG WITH A LOT OF GRAY COLORED OIL LEAKING FROM THE PUSH ROD HSG TUBES. REF RPM CHECK WAS FOUND TO BE LOW AND A COMPRESSON TEST WAS DONE AND FOUND TO BE 8/80 PSI UPON CLOSER INSP. IT WAS FOUND THAT THE HEAD OF THE CYL WAS ACTUALLY SPLITTING FROM THE BARREL.