A300
Flight Crew Air Transport Pilot (ATP)
Confusion
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Flight Crew Overcame Equipment Problem; Flight Crew Regained Aircraft Control
Aircraft
We were on arrival into ZZZ.  Autopilot was on and Profile was engaged.  Cost index was set to standard prior to descent.  After passing [an airspace fix] at 210 knots and approximately 9;100 feet; the aircraft abruptly pitched nose down and speed increased to approximately 225-230 knots.  I quickly selected 8;000 feet in the altitude preset window (required at or above altitude at [the intersection]) and Level Change on the FCP and the aircraft quickly slowed to 210 knots.  Total time of speed exceedance was about 7-10 seconds.  The remainder of the arrival was flown uneventfully in Level Change. While light turbulence could have played a small role; I am not sure why the aircraft pitched down so abruptly causing the speed increase.  All altitude restrictions were 'comfortably' made.   I have not seen this scenario before; but after discussions with other Airbus crewmembers; I learned that they have seen similar behavior at nearly the same point on this arrival.
A300 First Officer reports a sudden pitch over passing an airspace fix on a STAR; causing the speed to increase to 230 knots from 210 knots.  Other A300 crews have reported similar anomalies at the same location.