Narrative:

The approach was normal up to full flap extension. Flaps 1 and then 2 extensions were made while well outside the FAF and gear extension was made just before the FAF. Flaps full was selected just inside the FAF; I would guess at about 1400 ft AGL. Starting at about 1000 ft to 500 ft we felt a vibration very similar to that experienced with full spdbrake extension in-flight with a corresponding and fairly loud aerodynamic roaring sound that was immeidately noticed by me and my first officer. My first thought was that the spdbrakes had somehow become deployed. We both checked to make sure that they were indeed down and armed for landing. At that point; it seemed to be taking more power than normal to hold our approach speed which made me think that we could have had some in-flight icing. I verbalized this to the first officer and he scanned the right wing from his window. While there were no visual indications of icing on the ice probe; I asked the first officer to turn the wing heat on. After turning the wing heat on; the first officer again checked the wing and saw that the wing still appeared to be completely clean. The buffeting noise and vibration continued and I verbalized that I was going to add some speed to the approach and continue to land. The first officer agreed and we continued to a normal landing. The vibration ended as we touched down on the runway. I did notice that on approach I was using a little more power than normal. Generally I would have had about 2600 pounds per hour fuel flow on each engine during the last 1000 ft. On this approach I seem to recall needing close to 3400 pounds per hour to hold my speed. Upon clearing the runway; the first officer and I both agreed that the vibration we felt was way out of the ordinary and needed to be written up. I let the first officer go ahead and leave after we reached the gate. I called maintenance to give them a heads up on the forthcoming write up and then called maintenance operations control on my phone. I think it was while I was talking to maintenance control that the 2 flight attendants that were sitting in the rear of the aircraft came forward to brief me on their experience during the approach. They both told me that the vibration and noise they felt was far greater than anything they had experienced before and that they had started praying as they were both sure that the airplane was about to crash. The feeling I got was that several passenger in the back of the airplane were also very concerned about the noise and vibration. When I asked the flight attendants where they thought the noise and vibration were coming from they both said it seemed to be coming up from the floor. They were both visibly shaken by the experience and I do not doubt that they had been pretty scared. I continued to explain the best I could what I sensed and felt during the final stages of the approach to maintenance. Maintenance told me that he believed it to be a known flap problem with the airbus fleet but did not elaborate. At this point; our mechanics arrived and I once again explained the problem to them. I also filled out one of the vibration forms on the aircraft and gave it to one of the mechanics. At this point the outbound crew showed up and I briefed them on what had transpired. I then went out and completed the post flight inspection for myself to see if there was anything obvious that I could see that could explain the vibration and noise. There was no trace of ice and there were no obvious clues as to what had caused our experience.callback conversation with reporter revealed the following information: the reporter stated that in his followup about this event; he was told about an inboard flap attach bearing worn out of limits and the flap movement around the bearing. Additionally; the reporter said the flap actuator was at or beyond wear limits. Also of great concern to this reporter was that during troubleshooting; failed rudder attach bolts were found. Reporter stated it was assumed the bolt failures were the result of the vibrations.

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Original NASA ASRS Text

Title: AN A320 CREW RPTS AIRFRAME VIBRATION ON FINAL AFTER FLAP EXTENSION CAUSED BY A WORN FLAP BEARING AND FLAP ACTUATOR.

Narrative: THE APCH WAS NORMAL UP TO FULL FLAP EXTENSION. FLAPS 1 AND THEN 2 EXTENSIONS WERE MADE WHILE WELL OUTSIDE THE FAF AND GEAR EXTENSION WAS MADE JUST BEFORE THE FAF. FLAPS FULL WAS SELECTED JUST INSIDE THE FAF; I WOULD GUESS AT ABOUT 1400 FT AGL. STARTING AT ABOUT 1000 FT TO 500 FT WE FELT A VIBRATION VERY SIMILAR TO THAT EXPERIENCED WITH FULL SPDBRAKE EXTENSION INFLT WITH A CORRESPONDING AND FAIRLY LOUD AERODYNAMIC ROARING SOUND THAT WAS IMMEIDATELY NOTICED BY ME AND MY FO. MY FIRST THOUGHT WAS THAT THE SPDBRAKES HAD SOMEHOW BECOME DEPLOYED. WE BOTH CHKED TO MAKE SURE THAT THEY WERE INDEED DOWN AND ARMED FOR LNDG. AT THAT POINT; IT SEEMED TO BE TAKING MORE POWER THAN NORMAL TO HOLD OUR APCH SPD WHICH MADE ME THINK THAT WE COULD HAVE HAD SOME INFLT ICING. I VERBALIZED THIS TO THE FO AND HE SCANNED THE R WING FROM HIS WINDOW. WHILE THERE WERE NO VISUAL INDICATIONS OF ICING ON THE ICE PROBE; I ASKED THE FO TO TURN THE WING HEAT ON. AFTER TURNING THE WING HEAT ON; THE FO AGAIN CHKED THE WING AND SAW THAT THE WING STILL APPEARED TO BE COMPLETELY CLEAN. THE BUFFETING NOISE AND VIBRATION CONTINUED AND I VERBALIZED THAT I WAS GOING TO ADD SOME SPD TO THE APCH AND CONTINUE TO LAND. THE FO AGREED AND WE CONTINUED TO A NORMAL LNDG. THE VIBRATION ENDED AS WE TOUCHED DOWN ON THE RWY. I DID NOTICE THAT ON APCH I WAS USING A LITTLE MORE POWER THAN NORMAL. GENERALLY I WOULD HAVE HAD ABOUT 2600 LBS PER HOUR FUEL FLOW ON EACH ENG DURING THE LAST 1000 FT. ON THIS APCH I SEEM TO RECALL NEEDING CLOSE TO 3400 LBS PER HOUR TO HOLD MY SPD. UPON CLEARING THE RWY; THE FO AND I BOTH AGREED THAT THE VIBRATION WE FELT WAS WAY OUT OF THE ORDINARY AND NEEDED TO BE WRITTEN UP. I LET THE FO GO AHEAD AND LEAVE AFTER WE REACHED THE GATE. I CALLED MAINT TO GIVE THEM A HEADS UP ON THE FORTHCOMING WRITE UP AND THEN CALLED MAINT OPS CTL ON MY PHONE. I THINK IT WAS WHILE I WAS TALKING TO MAINT CTL THAT THE 2 FLT ATTENDANTS THAT WERE SITTING IN THE REAR OF THE ACFT CAME FORWARD TO BRIEF ME ON THEIR EXPERIENCE DURING THE APCH. THEY BOTH TOLD ME THAT THE VIBRATION AND NOISE THEY FELT WAS FAR GREATER THAN ANYTHING THEY HAD EXPERIENCED BEFORE AND THAT THEY HAD STARTED PRAYING AS THEY WERE BOTH SURE THAT THE AIRPLANE WAS ABOUT TO CRASH. THE FEELING I GOT WAS THAT SEVERAL PAX IN THE BACK OF THE AIRPLANE WERE ALSO VERY CONCERNED ABOUT THE NOISE AND VIBRATION. WHEN I ASKED THE FLT ATTENDANTS WHERE THEY THOUGHT THE NOISE AND VIBRATION WERE COMING FROM THEY BOTH SAID IT SEEMED TO BE COMING UP FROM THE FLOOR. THEY WERE BOTH VISIBLY SHAKEN BY THE EXPERIENCE AND I DO NOT DOUBT THAT THEY HAD BEEN PRETTY SCARED. I CONTINUED TO EXPLAIN THE BEST I COULD WHAT I SENSED AND FELT DURING THE FINAL STAGES OF THE APCH TO MAINT. MAINT TOLD ME THAT HE BELIEVED IT TO BE A KNOWN FLAP PROBLEM WITH THE AIRBUS FLEET BUT DID NOT ELABORATE. AT THIS POINT; OUR MECHANICS ARRIVED AND I ONCE AGAIN EXPLAINED THE PROBLEM TO THEM. I ALSO FILLED OUT ONE OF THE VIBRATION FORMS ON THE ACFT AND GAVE IT TO ONE OF THE MECHANICS. AT THIS POINT THE OUTBOUND CREW SHOWED UP AND I BRIEFED THEM ON WHAT HAD TRANSPIRED. I THEN WENT OUT AND COMPLETED THE POST FLT INSPECTION FOR MYSELF TO SEE IF THERE WAS ANYTHING OBVIOUS THAT I COULD SEE THAT COULD EXPLAIN THE VIBRATION AND NOISE. THERE WAS NO TRACE OF ICE AND THERE WERE NO OBVIOUS CLUES AS TO WHAT HAD CAUSED OUR EXPERIENCE.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT IN HIS FOLLOWUP ABOUT THIS EVENT; HE WAS TOLD ABOUT AN INBOARD FLAP ATTACH BEARING WORN OUT OF LIMITS AND THE FLAP MOVEMENT AROUND THE BEARING. ADDITIONALLY; THE RPTR SAID THE FLAP ACTUATOR WAS AT OR BEYOND WEAR LIMITS. ALSO OF GREAT CONCERN TO THIS RPTR WAS THAT DURING TROUBLESHOOTING; FAILED RUDDER ATTACH BOLTS WERE FOUND. RPTR STATED IT WAS ASSUMED THE BOLT FAILURES WERE THE RESULT OF THE VIBRATIONS.

Data retrieved from NASA's ASRS site as of January 2009 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.