A B737-300 IN DSCNT FROM FL310 EXPERIENCED A RATCHETING SOUND DUE TO STAB TRIM WHEEL MALFUNCTION AND EVENTUAL FAILURE. AUTOPLT WAS IN USE AT THE TIME.

Narrative

WHILE INBND TO ZZZ ON FLT AND DSNDING THROUGH FL310 THE STAB TRIM WHEEL BEGAN TO MAKE A RATCHETING TYPE SOUND AND WOULD NOT TRIM. I WAS FLYING AND THE CAPT ASKED ME TO TRY DISCONNECTING THE AUTOPLT AND TRIMMING USING THE ELECTRIC TRIM ON THE CONTROL YOKE. THE SAME RATCHETING NOISE WAS EXPERIENCED; BUT THE TRIM DID MOVE SOME; HOWEVER IT MADE A SQUEALING AND BINDING SOUND. WE THEN TRIED MANUALLY TRIMMING USING THE TRIM WHEEL HANDLE. INITIALLY WE HAD SOME SUCCESS; BUT THEN IT FINALLY FROZE UP COMPLETELY. AT THIS POINT WE WERE IN THE MID TEENS AND CENTER SWITCHED US TO APCH. WE RELAYED THE PROB TO THEM AND THEY ASKED US IF WE WERE DECLARING AN EMER AND IF WE NEEDED GND SUPPORT. ABOUT THAT TIME THE CAPT WHO WAS NOW WORKING WITH THE TRIM WHEEL GOT IT FREED UP AND INDICATED THAT NO; WE WERE NOT DECLARING AN EMER. HE THEN FLEW THE ACFT AND I GOT THE CHKLIST OUT AND WE RAN THE JAMMED STABILIZER CHKLIST. A NORMAL AND UNEVENTFUL FLAPS 30 LNDG WAS MADE AND THE ACFT WAS TAKEN OUT OF SVC. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED IT WAS ONLY ON APCH WHEN THE CAPT WAS WORKING ON THE LEFT MANUAL CTL WHEEL DID THE WHEELS FREE UP. THE RPTR SAID WHEN ON THE GND MAINT WAS ABLE TO DUPLICATE THE PROB AND DISCOVERED THE R MANUAL CTL WHEEL SHAFT BEARING POPPED OPEN AND THE BALLS OR ROLLER BEARINGS WERE MISSING.