As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CYLINDER NR 6 HAD BROKEN BOTH EXHAUST ROCKER SHAFT STUDS. HAPPENED ON SAME CYLINDER APPROXIMATELY 200 HOURS AGO ON A FACTORY CYLINDER WITH 1000 HOURS. PUSH ROD IS NOT BENT, LIFTER DOES NOT SHOW ANY SCORING. OUR ASSUMPTION IS THE LIFTER HYDRAULICALLY LOCKED AND PUT EXCESSIVE PRESSURE ON THE ROCKER CAUSING THE STUDS TO BREAK.