What was found
THE PILOT HEARD/FELT A POP, HAD AN INCREASE IN VIBRATION, AND A PARTIAL LOSS OF POWER. HE MADE AN EMERGENCY DESCENT TO A POWER ASSISTED LANDING IN THE TUNDRA, UPON LANDING SAW SMOKE COMING FROM THE ENGINE COMPARTMENT. SHUT DOWN AIRCRAFT. FOUND NO EVIDENCE OF FIRE. OIL ON EXHAUST, SAW OIL IN THE ENGINE COMPARTMENT. CALLED MAINTENANCE. UPON MAINTENANCE GETTING THERE, WE FOUND THE INTAKE VALVE ON THE #1 CYLINDER WAS MISSING. FURTHER INVESTIGATION FOUND THE VALVE STEM AT THE KEEPERS HAD BROKEN, AND LET THE VALVE FALL INTO THE CYLINDER. WE FOUND THE PARTS OF THE VALVE IN THE INTAKE SYSTEM OF THE ENGINE. THE PISTON AND THE CYLINDER HEAD WERE HAMMERED.