What was found
PRACTICING AN INSTRUMENT APPROACH INTO AIRPORT. PILOT FLYING WAS SLIGHTLY LOW ON A NON-PRECISION INSTRUMENT APPROACH. POWER SETTING WAS 15" MAP. APPLICATION OF FULL THROTTLE, DID NOT INCREASE MANIFOLD PRESSURE. AFTER SAFE LANDING ON RUNWAY WITH NO DAMAGE TO ACFT, REMOVED LOWER COWL ACCESS AND FOUND THE MS21042-5 NUT HAD COME LOOSE FROM THE THROTTLE SHAFT, ALLOWING THE THROTTLE ARM TO MOVE FREELY WITHOUT ACTUATING THE THROTTLE BUTTERFLY OR FUEL CONTROL. THE OLD STYLE BRASS THROTTLE ARM WAS INSTALLED, THE PN WAS 632081. THE MS21042-5 NUT DID NOT SHOW RESISTANCE FROM SHAFT, SUSPECT NUT WAS EITHER REUSED AT OVERHAUL OR WAS DEFECTIVE. THIS ENGINE DOES NOT INCORPORATE A SUPPLEMENTAL LOCKING DEVICE ON THE NUT SUCH AS A COTTER KEY. WE HAVE ORDERED A 656219 THROTTLE ARM AND NEW MS21042-5 NUT FOR THIS ACFT IAW CSB 08-3C.