A B747-400 IS ADVISED BY A GATE TECHNICIAN OF A RUDDER HYD LEAK. DURING LEAK CHK A 4 INCH BOLT IN THE RUDDER FEEL AND CTRING MECHANISM IS FOUND BACKED OUT AND RETAINING NUTS NOT ATTACHED.

Narrative

ON ARR AT GATE IN CHICAGO; MECH CAME UP TO COCKPIT AND STATED THERE WAS HYD FLUID LEAKING FROM TAIL AREA/RUDDER. UPON CLOSER INSPECTION (MECH TOOK CAPT AND I UP ON TOP OF TAIL IN A LIFT); MECH FOUND A SIGNIFICANT AMOUNT OF HYD FLUID LEAKING FROM THE RUDDER PCU AREA INSIDE OF VERT STABILIZER. ALSO DISCOVERED INSIDE OF VERT STABILIZER WAS A HINGE MECHANISM THAT APPEARED TO POSSIBLY DRIVE THE RUDDER. THIS MECHANISM HAD A BOLT (ABOUT 4 INCHES LONG) THAT WAS WORKING ITS WAY UP AND OUT OF HINGE MECHANISM. BELOW BOLT WERE 2 NUTS THAT APPEARED TO HAVE FALLEN OFF THE BOTTOM OF THE BOLT. ACFT WAS GROUNDED AT THIS POINT AND MECHS NOTIFIED FAA AND NTSB. (RUDDER HAD BEEN WRITTEN UP 3 PREVIOUS TIMES RECENTLY FOR UNCOMMANDED MOVEMENT. MAINT HAD PLACED THE YAW DAMPER ON MEL.) CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE AIRPLANE WAS CARRYING A DEFERRED ITEM ON THE YAW DAMPER AND HAD A LONG MAINT HISTORY. THE RPTR SAID A FEW DAYS LATER HE TALKED TO THE TECHNICIAN WHO DISCOVERED THE LEAK AND OPENED UP THE VERT STABILIZER TO FIND OUT WHAT COMPONENT WAS INVOLVED. THE RPTR STATED THE 4 INCH BOLT WAS IN THE FEEL AND CTRING UNIT BUT IS UNAWARE OF THE EXACT LOCATION ON THE MECHANISM.