Narrative:

After a night flight from south america a routine landing and parking at the terminal gate occurred. Observed parking mechanic give stop signal at which time brakes were set and brake handle verified engaged. Mechanic left position at the front of aircraft, I assumed to connect ground power, and I then looked toward jetway to verify passenger service people were aware of our arrival. There was no detectable aircraft movement. At this time I returned my attention to the flight deck and shutdown procedures. While moving seat and head position around panels I detected no aircraft movement. Out of the corner of my eye I detected lights and activity. The parking mechanic was jumping up and down to get my attention. As soon as he saw we had eye contact he indicated aircraft was moving by a rolling motion of his batons. I still sensed no motion but quickly slid seat forward and applied brakes. No sensation of stopping occurred, but aircraft did stop. Either rapid body movements, seat movement, very slow aircraft movement, or aircraft had already stopped on its own could have eliminated some of the sensation of stop. Darkness definitely affected outside reference. While passenger were deplaning a ramp supervisor came on board to advise we had hit a piece of ground equipment with the right engine cowling (had been shut down). Neither cockpit crewmember sensed or felt motion or impact. Suspect a failure in brake system occurred. Preventing such incidents could be accomplished by a definite chocking indication before any cockpit internal activity and no vehicle activity near aircraft until all engines are shut down and beacon turned off. The left engine was still running at occurrence.

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Original NASA ASRS Text

Title: ACFT EQUIP PROB -- ACFT DAMAGED -- ACR FLC SET THE PARKING BRAKE, BUT THE ACFT ROLLED AND STRUCK GND EQUIP.

Narrative: AFTER A NIGHT FLT FROM S AMERICA A ROUTINE LNDG AND PARKING AT THE TERMINAL GATE OCCURRED. OBSERVED PARKING MECH GIVE STOP SIGNAL AT WHICH TIME BRAKES WERE SET AND BRAKE HANDLE VERIFIED ENGAGED. MECH LEFT POS AT THE FRONT OF ACFT, I ASSUMED TO CONNECT GND PWR, AND I THEN LOOKED TOWARD JETWAY TO VERIFY PAX SVC PEOPLE WERE AWARE OF OUR ARR. THERE WAS NO DETECTABLE ACFT MOVEMENT. AT THIS TIME I RETURNED MY ATTN TO THE FLT DECK AND SHUTDOWN PROCS. WHILE MOVING SEAT AND HEAD POS AROUND PANELS I DETECTED NO ACFT MOVEMENT. OUT OF THE CORNER OF MY EYE I DETECTED LIGHTS AND ACTIVITY. THE PARKING MECH WAS JUMPING UP AND DOWN TO GET MY ATTN. AS SOON AS HE SAW WE HAD EYE CONTACT HE INDICATED ACFT WAS MOVING BY A ROLLING MOTION OF HIS BATONS. I STILL SENSED NO MOTION BUT QUICKLY SLID SEAT FORWARD AND APPLIED BRAKES. NO SENSATION OF STOPPING OCCURRED, BUT ACFT DID STOP. EITHER RAPID BODY MOVEMENTS, SEAT MOVEMENT, VERY SLOW ACFT MOVEMENT, OR ACFT HAD ALREADY STOPPED ON ITS OWN COULD HAVE ELIMINATED SOME OF THE SENSATION OF STOP. DARKNESS DEFINITELY AFFECTED OUTSIDE REF. WHILE PAX WERE DEPLANING A RAMP SUPVR CAME ON BOARD TO ADVISE WE HAD HIT A PIECE OF GND EQUIP WITH THE R ENG COWLING (HAD BEEN SHUT DOWN). NEITHER COCKPIT CREWMEMBER SENSED OR FELT MOTION OR IMPACT. SUSPECT A FAILURE IN BRAKE SYS OCCURRED. PREVENTING SUCH INCIDENTS COULD BE ACCOMPLISHED BY A DEFINITE CHOCKING INDICATION BEFORE ANY COCKPIT INTERNAL ACTIVITY AND NO VEHICLE ACTIVITY NEAR ACFT UNTIL ALL ENGS ARE SHUT DOWN AND BEACON TURNED OFF. THE L ENG WAS STILL RUNNING AT OCCURRENCE.

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.