19961124042649I

NARRATIVE: ON NOVEMBER 24, 1996, WHILE ON APPROACH INTO DETROIT WAYNE COUNTY AIRPORT, NORTHWEST AIRLINES FLIGHT 211'S CAPTAIN REPORTED "AFTER APPROACH IN LIGHT ICING CONDITIONS (WITH WING AND ENGINE ANTI-ICE ON), RUDDER PEDALS STUCK IN NEUTRAL POSITION. AUTOPILOT WAS OFF. RETURNED TO NORMAL DURING TAXI." PILOT STATEMENTS DESCRIBE THE OCCURRENCE AS SUCH, "RUDDER PEDALS WOULD NOT MOVE DURING FLARE AND ROLL OUT." "THE RUDDER PEDALS SEEMED STIFF OR POSSIBLY LOCKED UP." ^PRIVACY DATA OMITTED^ STATED HE WAS AT THE CONTROLS CONDUCTING A MANUAL ILS APPROACH. THE AUTOPILOT WAS DISENGAGED APPROXIMATELY 15 MILES FROM THE AIRPORT AND PRIOR TO MAKING THE TURN TO INTERCEPT FINAL. ^PRIVACY DATA OMITTED^ STATED THE AIRCRAFT FLEW NORMALLY WITH NO ADVERSE YAW NOTICED DURING THE TURN. THE RUDDER/YAW DAMPER APPEARED TO BE WORKING NORMALLY. SPEED ON FINAL WAS REPORTED TO BE 141 KNOTS. THERE WAS A RIGHT QUARTERING TAIL WIND WHICH SUBSIDED TO A VERY LIGHT RIGHT CROSS WIND OVER THE RUNWAY THRESHOLD. DUE TO THIS LIGHT CROSS WIND, A SLIGHT APPLICATION OF RUDDER/WING LOW COMPENSATION WAS REQUIRED FOR THE FLAIR AND LANDING. ^PRIVACY DATA OMITTED^ STATED THAT WHEN HE ATTEMPTED TO APPLY RUDDER, IT WAS FOUND THAT THE PEDALS WERE LOCKED IN THE NEUTRAL POSITION. SLIGHT BANKING TOWARD RUNWAY CENTERLINE ALLOWED A NORMAL TOUCH DOWN. DIFFERENTIAL BRAKING AND NOSE WHEEL STEERING WERE USED TO EXIT THE RUNWAY. ^PRIVACY DATA OMITTED^ STATED, WHILE STOPPED, HE PERFORMED SEVERAL AUTOPILOT DISCONNECTS TO VERIFY THE AUTOPILOT WAS DISCONNECTED. HE STATED HE MADE SEVERAL ATTEMPTS TO MOVE THE RUDDER PEDALS. AFTER ABUT 15 SECONDS OF THIS, THE RUDDER BECAME FREE AND MOVED NORMALLY. ^PRIVACY DATA OMITTED^ STATED NO GREAT PRESSURE WAS EVER EXERTED IN ATTEMPTING TO REGAIN RUDDER. HE STATED HE DID NOT TRY TO "BREAK CONTROLS FREE." THERE WERE NO AIRCRAFT WARNING AND NO SYSTEM MONITORING MESSAGES TO SUGGEST WHAT MAY HAVE OCCURRED. ^PRIVACY DATA OMITTED^ ALSO NOTED THE RUDDER PEDALS WERE STIFF. HE STATED THAT ON THE NEXT FLIGHT HE AND ^PRIVACY DATA OMITTED^ FLEW TOGETHER, HE PUT HIS FEET ON THE RUDDER PEDALS WHILE THE AUTOPILOT WAS ON. HE NOTED THAT THE STIFF FEEL OF THE RUDDER PEDALS, WITH THE AUTOPILOT ON, WAS SIMILAR TO THE FEEL HE HAD EXPERIENCED WITH THE STIFF RUDDER PEDALS OF ^PRIVACY DATA OMITTED^. NORTHWEST AIRLINES' DETROIT MAINTENANCE WAS NOT ABLE TO DUPLICATE THE STIFF RUDDER PEDAL DISCREPANCY. COLD SOAKING WITH DRY ICE WAS DONE TO RUDDER ATTACH POINTS. AS A PRECAUTION, THE RUDDER ARTIFICIAL FEEL AND TRIM UNIT SOLENOID, MFG. P/N450EP01Y, S/N 224, WAS REPLACED. A FLIGHT TEST WAS DONE AND THE AIRCRAFT WAS RETURNED TO SERVICE. FAA REVIEW OF AIRBUS SERVICE HISTORY DISCLOSED THE AIRCRAFT MANUFACTURE HAS HAD EXPERIENCE WITH STIFF RUDDER PEDALS. AIRBUS TECHNICAL FOLLOW UP (TFU)27.23.48.01, OCTOBER 15, 1990 AND TFU 27.23.00.01, APRIL 11, 1991 (ATTACHMENT 1), INFORM OF SEVERAL CASES OF STIFF RUDDER PEDALS. THE RUDDER PEDALS WERE DIFFICULT TO MOVE DURING FINAL FLIGHT PHASE AFTER AUTOPILOT DISENGAGEMENT. AIRBUS EXAMINATION HAS DETERMINED THAT THE AUTOPILOT WAS DISENGAGED. AIRBUS EVALUATION OF TWO ARTIFICIAL FEEL AND TRIM UNITS REMOVED FROM TROUBLED AIRCRAFT WERE TESTED IN ICING CONDITIONS. THE TESTS CONFIRMED THE FAILURE OF THE ARTIFICIAL FEEL AND TRIM UNIT TO DISENGAGE WHEN AUTOPILOT WAS DISCONNECTED. THE SOLENOID WAS NOT ABLE TO MOVE THE CONNECT/DISCONNECT LEVER DUE TO JAMMING OF THE LEVER. AIRBUS RELEASED SERVICE BULLETIN, A320-27-1042, MARCH 21, 1992(ATTACHMENT 2), TO CORRECT THIS OCCURRENCE. NORTHWEST AIRLINES HAD NOT INCORPORATED SERVICE BULLETIN, A320-27-1042. AT T HEREQUEST OF THE FAA-NWA-CMO, NORTHWEST REMOVED THE UNMODIFIED RUDDER ARTIFICIAL FEEL AND TRIM UNIT, MFG. P/N D27270400-00600, S/N-123,MFG. DATE OCTOBER 1989, TO AIRBUS FOR EVALUATION.