As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT ENGINE PILOT NOTICED PARTIAL POWER LOSS. AFTER LANDING THERE WAS A LARGE OIL LEAK FROM THE NR 6 EXHAUST PUSHROD TUBE WHICH HAD BEEN JARRED LOOSE AND UNCLIPPED. THE CAM FOLLOWER WAS BROKEN. THE TANG ON THE ROCKER COVER THAT HOLDS THE EXHAUST ROCKER SHAFT IN WAS BROKEN POSSIBLY LODGING IN THE VALVE SPRING CAUSE EXCESSIVE VALVE LASH.