As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE STARTED RUNNING ROUGH AND PILOT NOTICED OIL LEAKING ON COWLING. ENGINE WAS SECURED AND A UNEVENTFUL LANDING MADE. MAINT FOUND CYL NR 4 HAVING BROKEN STUDS AND CYLINDER STARTING TO SEPARATE FROM ENGINE. ALSO FOUND ROCKER BOX COVER SCREWS LOOSE/MISSING. ENGINE REMOVED FOR REPAIR. (K)