Narrative:

On arrival at gate in chicago, mechanic came up to cockpit and stated there was hydraulic fluid leaking from tail area/rudder. Upon closer inspection (mechanic took captain and I up on top of tail in a lift), mechanic found a significant amount of hydraulic fluid leaking from the rudder PCU area inside of vertical stabilizer. Also discovered inside of vertical 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. Aircraft was grounded at this point and mechanics notified FAA and NTSB. (Rudder had been written up 3 previous times recently for uncommanded movement. Maintenance had placed the yaw damper on MEL.) callback conversation with reporter revealed the following information: the reporter stated the airplane was carrying a deferred item on the yaw damper and had a long maintenance history. The reporter said a few days later he talked to the technician who discovered the leak and opened up the vertical stabilizer to find out what component was involved. The reporter stated the 4 inch bolt was in the feel and ctring unit but is unaware of the exact location on the mechanism.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.