A B767-200 DURING THE OVERWATER PREFLT CHK IT WAS DISCOVERED THE RUDDER TRIM KNOB DID NOT RETURN TO THE SPRING LOADED CTR POS BUT CONTINUED TO DRIVE THE RUDDER TRIM.

Narrative

DURING PREFLT; RAN SMALL AMOUNT OF RUDDER TRIM IN ACCORDANCE WITH CHKLIST. RUDDER CONTINUED TO RUN WHEN KNOB WAS RELEASED INSTEAD OF STOPPING. TRIM KNOB DID NOT RETURN TO CTR POS. TO STOP THE RUDDER; I ROTATED THE KNOB TO CTR. I NOTICED IT WAS BINDING AGAINST THE PEDESTAL. WE WERE ABLE TO PULL UP ON THE KNOB; WHICH THEN WORKED NORMALLY. THIS PROB WAS CAUGHT DURING AN ORIGINATION; BUT MIGHT NOT HAVE BEEN NOTICED DURING A CLEAN-UP INSPECTION WHERE THE TRIM IS CHKED TO BE AT ZERO; WHICH IT WAS. WE SUSPECT A KIT BAG WAS PLACED ON THE PEDESTAL WHEN THE PRECEDING CREW LEFT THE FLT DECK. SUCH A PROB COULD EASILY GO UNDETECTED UNTIL TRIM IS NEEDED AFTER DEP WHILE LOW; SLOW; AND HVY. IT COULD ALSO BE MISDIAGNOSED AS AN ENG ROLLBACK OR FLT CTL ASYMMETRY PROB. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT WAS A B767-200 OVERWATER ACFT AND WAS ACCOMPLISHING THE ORIGINATION PREFLT CHK WHEN THE OP OF THE RUDDER TRIM KNOB WAS NOTED. THE RPTR SAID THE TRIM KNOB WOULD NOT RETURN TO THE CTR SPRING LOADED POS AFTER DISPLACING THE KNOB FROM CTR BUT CONTINUED TO DRIVE THE TRIM ACTUATOR. THE RPTR SAID THE KNOB JAMMED ON THE PEDESTAL SURFACE. THE RPTR STATED THIS COULD BE A PROB ON THROUGH FLTS WHERE THE CHKLIST DOES NOT REQUIRE CHKING TRIM KNOB OP. THE RPTR SAID THE KNOB ADJUSTMENT OR LOCK SCREW APPEARED LOOSE. THE RPTR STATED THE KNOB WAS RPTED AT THE NEXT STATION BUT IS NOT AWARE OF THE FIX.