What was found
THE CREW REPORTED THAT DURING CRUISE FLIGHT AT FL 380 THE AUTO-TRIM ANNUNCIATOR ILLUMINATED. AFTER DISCONNECTING THE AUTO-PILOT THE TRIM WHEEL WAS FOUND TO BE STUCK. THE TRIM WHEEL BECAME EASIER TO MOVE DURING DESCENT AT A LOWER ALTITUDE. OPERATION ON THE GROUND AFTER THE FLIGHT WAS NORMAL. MAINTENANCE ACCOMPLISHED A SATISFACTORY ELEVATOR TRIM STATIC FRICTION CHECK. A SATISFACTORY FUNCTIONAL TEST WAS PERFORMED ON THE ELEVATOR TRIM CONTROL SYSTEM. THE LEFT AND RIGHT ELEVATOR TRIM JACKS WERE CHECKED AND LUBRICATED. THE AIRCRAFT WAS RETURNED TO SERVICE.