A B737-300 in descent from FL310 experienced a ratcheting sound due to stabilizer trim wheel malfunc...

Attributes
ACN	598117
Time
Date	200311
Day	Mon
Place
Locale Reference	airport : zzz.airport
Altitude	msl bound lower : 15000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zzz.artcc tracon : zzz.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 250 flight time total : 8100 flight time type : 3000
ASRS Report	598117
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : overcame equipment problem flight crew : regained aircraft control
Consequence	other other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

While inbound to ZZZ on flight and descending through FL310 the stabilizer trim wheel began to make a ratcheting type sound and would not trim. I was flying and the captain 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 approach. We relayed the problem to them and they asked us if we were declaring an emergency and if we needed ground support. About that time the captain who was now working with the trim wheel got it freed up and indicated that no, we were not declaring an emergency. He then flew the aircraft and I got the checklist out and we ran the jammed stabilizer checklist. A normal and uneventful flaps 30 landing was made and the aircraft was taken out of service. Callback conversation with reporter revealed the following information: the reporter stated it was only on approach when the captain was working on the left manual control wheel did the wheels free up. The reporter said when on the ground maintenance was able to duplicate the problem and discovered the right manual control wheel shaft bearing popped open and the balls or roller bearings were missing.

Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

A B737-300 in descent from FL310 experienced a ratcheting sound due to stabilizer trim wheel malfunction and eventual failure. Autoplt was in use at the time.