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Flight crew of B734 experienced jammed stabilizer trim at top of descent. Utilized abnormal procedures checklists and diverted to mco due to longer runways and better WX.
| Attributes | |
| ACN | 588136 |
| Time | |
| Date | 200307 |
| Day | Mon |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : tpa.airport |
| State Reference | FL |
| Altitude | msl single value : 28000 |
| Environment | |
| Flight Conditions | Mixed |
| Weather Elements | Thunderstorm |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : ztl.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737-400 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | cruise : level descent : vacating altitude |
| Route In Use | enroute airway : j39.airway |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : multi engine pilot : instrument pilot : flight engineer pilot : commercial pilot : atp |
| Experience | flight time last 90 days : 16 flight time total : 19000 flight time type : 15000 |
| ASRS Report | 588136 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | aircraft equipment problem : critical inflight encounter : weather |
| Independent Detector | aircraft equipment other aircraft equipment : jammed stabilizer other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : overcame equipment problem flight crew : declared emergency flight crew : diverted to another airport flight crew : landed as precaution flight crew : landed in emergency condition |
| Consequence | other other |
| Supplementary | |
| Problem Areas | Aircraft Maintenance Human Performance Flight Crew Human Performance |
| Primary Problem | Aircraft |
Narrative:
Stabilizer trim wheel was making a clunking noise at cruise when the autoplt trimmed. At top of descent, the wheel froze with the motor still running. Ran the checklist, turning of the automatic/main electrical trim. Diverted from pns to mco for WX and added runway length. Declared emergency. Began long slow descent to visual landing runway 18R mco. Controls were heavy and trim wheel required 2 pilot input to turn. Landing uneventful. Not knowing control forces required, we had flight attendants prepare cabin. Because of thunderstorms, we changed destination from pns to mco (long and dry). Callback conversation with reporter revealed the following information: reporter advised that discussions with maintenance the following day indicated they had lubricated the chain in the stabilizer trim drive mechanism and released the aircraft to service.
Original NASA ASRS Text
Title: FLT CREW OF B734 EXPERIENCED JAMMED STABILIZER TRIM AT TOP OF DSCNT. UTILIZED ABNORMAL PROCS CHKLISTS AND DIVERTED TO MCO DUE TO LONGER RWYS AND BETTER WX.
Narrative: STABILIZER TRIM WHEEL WAS MAKING A CLUNKING NOISE AT CRUISE WHEN THE AUTOPLT TRIMMED. AT TOP OF DSCNT, THE WHEEL FROZE WITH THE MOTOR STILL RUNNING. RAN THE CHKLIST, TURNING OF THE AUTO/MAIN ELECTRICAL TRIM. DIVERTED FROM PNS TO MCO FOR WX AND ADDED RWY LENGTH. DECLARED EMER. BEGAN LONG SLOW DSCNT TO VISUAL LNDG RWY 18R MCO. CTLS WERE HVY AND TRIM WHEEL REQUIRED 2 PLT INPUT TO TURN. LNDG UNEVENTFUL. NOT KNOWING CTL FORCES REQUIRED, WE HAD FLT ATTENDANTS PREPARE CABIN. BECAUSE OF TSTMS, WE CHANGED DEST FROM PNS TO MCO (LONG AND DRY). CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ADVISED THAT DISCUSSIONS WITH MAINT THE FOLLOWING DAY INDICATED THEY HAD LUBRICATED THE CHAIN IN THE STABILIZER TRIM DRIVE MECHANISM AND RELEASED THE ACFT TO SVC.
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.