AN MD SUPER 80 ON TAXI OUT RETURNED TO THE GATE DUE TO THE RUDDER CTL FAILURE DISCOVERED DURING THE RUDDER CTL CHKLIST PROC.

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DURING THE TAXI CHKLIST/FLT CTL CHK; WE NOTICED THAT WHEN THE CAPT APPLIED R RUDDER; THE RUDDER TRAVEL UNRESTR ANNUNCIATOR LIGHT WENT OUT AS R RUDDER WAS APPLIED AND WOULD REILLUMINATE AS L RUDDER WAS APPLIED AND THE R RUDDER APCHED THE NEUTRAL POS. NEITHER OF US HAD EVER SEEN THIS BEFORE SO WE STOPPED; CHKED THE ABNORMAL CHKLISTS IN THE OPS MANUAL PART 1. THERE IS NO MENTION OF THIS CONDITION IN THE MANUAL; SO WE ARRANGED A PHONE PATCH TO TULSA TECHNICIAN AND DISCUSSED THE PROB WITH THE DUTY ENGINEER. WE ALL AGREED THAT THERE WAS A PROB AND WE TAXIED BACK TO THE GATE AND CALLED A MECH. THE MECH ARRIVED AND VIA CELL PHONE TO TULSA WE DISCOVERED A PORTION OF THE RUDDER SYS WAS OUT OF ADJUSTMENT. THE MECH WAS ABLE TO ADJUST THE EQUIP AND WE FINISHED THE LOG AND DEPARTED. AFTER RETURNING TO DFW; I CALLED THE DC9 FLEET SUPVR/CAPT TO DISCUSS THE OCCURRENCE. HE HAD NEVER HEARD OF THIS HAPPENING EITHER AND PROMISED TO FOLLOW UP. SUPVR/CAPT CONFERRED WITH PERSON AT MAINT AND THEY INFORMED ME THAT THE PROB AS ENCOUNTERED BY US COULD BE A SERIOUS SIT SHOULD THE RUDDER BE RESTR AND WE EXPERIENCE AN ENG FAILURE REQUIRING USE OF FULL RUDDER TRAVEL. I FEEL A CHANGE TO THE TAXI CHKLIST IS NEEDED IN THE FORM OF A NOTE TO ENSURE THAT THE RUDDER TRAVEL UNRESTR LIGHT STAYS ILLUMINATED WHILE COMPLETING THE RUDDER CTL CHK. I REALIZE THAT IN THE INTEREST OF BREVITY AND TIMELINESS; I HAVE LEFT OUT DETAILS OF THIS OCCURRENCE. I WILL BE AVAILABLE TO DEBRIEF CONCERNED INDIVIDUALS AS NEEDED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE RUDDER UNRESTR LIGHT SHOULD ALWAYS BE ON WITH NO INPUT FROM THE AIRSPD BELLOWS. THE RPTR STATED ON THE GND DURING TAXI OUT THE LIGHT WENT OUT INDICATING THE RUDDER HAD A RESTR WITH R RUDDER INPUT. THE RPTR SAID NEITHER THE CAPT NOR THE RPTR HAD EVER EXPERIENCED THIS TYPE OF FAILURE. THE RPTR SAID MAINT FOUND THE RUDDER TRAVEL UNRESTR SWITCH MOUNTING PLATE ON THE RUDDER HYD PWR PACKAGE OUT OF ADJUSTMENT. THE RPTR STATED THE MAJOR CONCERN WAS THE RUDDER RESTR DURING TKOF IN AN ENG OUT SIT WHEN A LOT OF RUDDER IS REQUIRED. THE RPTR SAID HE WAS UNAWARE IF THE ACFT HAD ANY PREVIOUS HISTORY ON RUDDER INDICATION PROBS.