Narrative:

On or about XA30 on nov/thu/04, I received a phone call from quality control to inform me of a flight control discrepancy which had occurred on air carrier X. The flight crew reported a rudder travel problem and after a gate return, it was determined that a rudder nose fairing was causing interference with the rudder PCU mechanism. Further investigation revealed that the rudder nose fairing which was installed was not the correct part due to the fact that engineering authority/authorized, which was recently performed at ZZZ, requires that a new modifier rudder nose fairing be installed. As I was the inspector which bought off the installation of the incorrect fairing panels, I was asked for an explanation of what had occurred. After reviewing the engineering authority/authorized paperwork, I have determined that I did inadvertently buy off on the installation of the improper rudder nose fairing. Further review of the paperwork and conversation with the technicians involved have shed some light on how this error occurred. Step 39 near the beginning of the procedure comprising open-up states 'remove and discard the 3 cover panels' (1 on the left side, 2 on the right side). These are the original nose fairings in question and are not inspection buy-off. Steps 40-47 then entail the drilling up of the new nose fairings. Apparently, the sheet metal technician which was assigned this part of the job (but was not the one which removed the originals) used the originals as a template to pick up the holes and were not discarded, but were then placed in the rack with the rest of the rudder access panels. The new fairing panels are not called out for installation until steps 87, 88, and 89, but due to recent experience, the panels are often not installed at that time because of numerous instances of leaking PCU's which then require subsequent removal as well as being part of normal rudder close up after all maintenance is complete. The final contributing factor is that although the installation step for the fairings does specify part numbers for the new panels, there is no other mention or reminder that these are in fact new design panels. As a result, in this instance several days had elapsed and a different technician, which picked up on the job, as well as myself missed the part number designation and installed the original fairing panels as part of normal rudder close up. Contributing factors: technical data -- engineering authority/authorized inspection buy-off should be added to destroy old parts installation steps should coincide better with actual work flow. Communication -- different technicians, different inspectors resulted in communication breakdown. Callback conversation with reporter revealed the following information: the reporter stated the engineering authority/authorized job card for the modification of the rudder fairing contributed to the wrong parts being installed on the rudder fairing. The original fairings were to be removed and discarded but they were not discarded, but held to copy the fastener pattern on the new fairing panels. Technician working the panels drilled the new panels using the removed panels for a template, but did not discard the removed panels, but placed them in a rack with the new panels. This job went on for several days and another technician installed the original removed fairings. Callback conversation with reporter acn 636361 revealed the following information: reporter stated he used the old panels removed from another job card and drilled the new fairings. Painted the new fairings and put them to dry on the sheet metal rack.

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Original NASA ASRS Text

Title: A B737-300 RPTED A RUDDER TRAVEL PROB. FOUND MODIFIED RUDDER PWR UNIT INSTALLED, BUT UNMODIFIED RUDDER NOSE FAIRING INADVERTENTLY INSTALLED.

Narrative: ON OR ABOUT XA30 ON NOV/THU/04, I RECEIVED A PHONE CALL FROM QUALITY CTL TO INFORM ME OF A FLT CTL DISCREPANCY WHICH HAD OCCURRED ON ACR X. THE FLT CREW RPTED A RUDDER TRAVEL PROB AND AFTER A GATE RETURN, IT WAS DETERMINED THAT A RUDDER NOSE FAIRING WAS CAUSING INTERFERENCE WITH THE RUDDER PCU MECHANISM. FURTHER INVESTIGATION REVEALED THAT THE RUDDER NOSE FAIRING WHICH WAS INSTALLED WAS NOT THE CORRECT PART DUE TO THE FACT THAT ENGINEERING AUTH, WHICH WAS RECENTLY PERFORMED AT ZZZ, REQUIRES THAT A NEW MODIFIER RUDDER NOSE FAIRING BE INSTALLED. AS I WAS THE INSPECTOR WHICH BOUGHT OFF THE INSTALLATION OF THE INCORRECT FAIRING PANELS, I WAS ASKED FOR AN EXPLANATION OF WHAT HAD OCCURRED. AFTER REVIEWING THE ENGINEERING AUTH PAPERWORK, I HAVE DETERMINED THAT I DID INADVERTENTLY BUY OFF ON THE INSTALLATION OF THE IMPROPER RUDDER NOSE FAIRING. FURTHER REVIEW OF THE PAPERWORK AND CONVERSATION WITH THE TECHNICIANS INVOLVED HAVE SHED SOME LIGHT ON HOW THIS ERROR OCCURRED. STEP 39 NEAR THE BEGINNING OF THE PROC COMPRISING OPEN-UP STATES 'REMOVE AND DISCARD THE 3 COVER PANELS' (1 ON THE L SIDE, 2 ON THE R SIDE). THESE ARE THE ORIGINAL NOSE FAIRINGS IN QUESTION AND ARE NOT INSPECTION BUY-OFF. STEPS 40-47 THEN ENTAIL THE DRILLING UP OF THE NEW NOSE FAIRINGS. APPARENTLY, THE SHEET METAL TECHNICIAN WHICH WAS ASSIGNED THIS PART OF THE JOB (BUT WAS NOT THE ONE WHICH REMOVED THE ORIGINALS) USED THE ORIGINALS AS A TEMPLATE TO PICK UP THE HOLES AND WERE NOT DISCARDED, BUT WERE THEN PLACED IN THE RACK WITH THE REST OF THE RUDDER ACCESS PANELS. THE NEW FAIRING PANELS ARE NOT CALLED OUT FOR INSTALLATION UNTIL STEPS 87, 88, AND 89, BUT DUE TO RECENT EXPERIENCE, THE PANELS ARE OFTEN NOT INSTALLED AT THAT TIME BECAUSE OF NUMEROUS INSTANCES OF LEAKING PCU'S WHICH THEN REQUIRE SUBSEQUENT REMOVAL AS WELL AS BEING PART OF NORMAL RUDDER CLOSE UP AFTER ALL MAINT IS COMPLETE. THE FINAL CONTRIBUTING FACTOR IS THAT ALTHOUGH THE INSTALLATION STEP FOR THE FAIRINGS DOES SPECIFY PART NUMBERS FOR THE NEW PANELS, THERE IS NO OTHER MENTION OR REMINDER THAT THESE ARE IN FACT NEW DESIGN PANELS. AS A RESULT, IN THIS INSTANCE SEVERAL DAYS HAD ELAPSED AND A DIFFERENT TECHNICIAN, WHICH PICKED UP ON THE JOB, AS WELL AS MYSELF MISSED THE PART NUMBER DESIGNATION AND INSTALLED THE ORIGINAL FAIRING PANELS AS PART OF NORMAL RUDDER CLOSE UP. CONTRIBUTING FACTORS: TECHNICAL DATA -- ENGINEERING AUTH INSPECTION BUY-OFF SHOULD BE ADDED TO DESTROY OLD PARTS INSTALLATION STEPS SHOULD COINCIDE BETTER WITH ACTUAL WORK FLOW. COM -- DIFFERENT TECHNICIANS, DIFFERENT INSPECTORS RESULTED IN COM BREAKDOWN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ENGINEERING AUTH JOB CARD FOR THE MODIFICATION OF THE RUDDER FAIRING CONTRIBUTED TO THE WRONG PARTS BEING INSTALLED ON THE RUDDER FAIRING. THE ORIGINAL FAIRINGS WERE TO BE REMOVED AND DISCARDED BUT THEY WERE NOT DISCARDED, BUT HELD TO COPY THE FASTENER PATTERN ON THE NEW FAIRING PANELS. TECHNICIAN WORKING THE PANELS DRILLED THE NEW PANELS USING THE REMOVED PANELS FOR A TEMPLATE, BUT DID NOT DISCARD THE REMOVED PANELS, BUT PLACED THEM IN A RACK WITH THE NEW PANELS. THIS JOB WENT ON FOR SEVERAL DAYS AND ANOTHER TECHNICIAN INSTALLED THE ORIGINAL REMOVED FAIRINGS. CALLBACK CONVERSATION WITH RPTR ACN 636361 REVEALED THE FOLLOWING INFO: RPTR STATED HE USED THE OLD PANELS REMOVED FROM ANOTHER JOB CARD AND DRILLED THE NEW FAIRINGS. PAINTED THE NEW FAIRINGS AND PUT THEM TO DRY ON THE SHEET METAL RACK.

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.