What was found
TURNING DOWNWIND FROM CROSSWIND THERE WAS A SINKING FEELING TO THE PLANE IN WHICH I TOOK OVER CONTROLS IMMEDIATELY CHECKED TO SEE IF POWER WAS FULL. THE POWER HANDLE WAS FULL BUT IT FELT AS IF WE HAD A LOSS OF THRUST, THEN THE RPM’S BEGAN TO RAPIDLY DROP AND SPIKE. THEN A NOISE STARTED COMING FROM THE ENGINE. IT SOUNDED LIKE SOMETHING SHEARED AND WAS DESTROYING THE ENGINE FROM THE INSIDE. LANDED AIRCRAFT AS SOON AS POSSIBLE. TOWER WAS ADVISED. MX INSPECTED THE ENGINE AND FOUND THE #4 CYLINDER EXHAUST VALVE HAD STUCK OPEN AND BROKE OFF. LARGE METAL FLAKES WERE FOUND IN THE #4 CYLINDER AND IN THE OIL SUMP SCREEN. ENGINE IS TO BE REMOVED AND SENT OUT FOR OVERHAUL.