AN ACR DC10 FLC HAD THE #2 AUTOPLT DISCONNECT AS THEY WERE APCHING LEVELOFF AT FL370. SHORTLY AFTER LEVELOFF; THE ACFT EXPERIENCED SEVERAL EPISODES OF VIBRATION ACCOMPANIED BY THE UPPER YAW DAMPER INOP LIGHTS ILLUMINATING. MAINT PERSONNEL COULD NOT DETERMINE THE CAUSE OF THE VIBRATIONS.

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FLT WAS ENRTE TO AMSTERDAM FROM NEW YORK AND HAD JUST CHKED IN WITH SCOTTISH CTL AT FL350. CLRNC WAS GIVEN TO CLB TO FL370. APPROX 200 FT BELOW LEVELOFF; THE #2 AUTOPLT TRIPPED OFF. COPLT WAS PF AND HE LEVELED OFF MANUALLY AT FL370 AND ATTEMPTED TO RE-ENGAGE THE #2 AUTOPLT. IT TRIPPED OFF AGAIN AND THIS WAS FOLLOWED BY STRONG ACFT VIBRATIONS AND PITCH OSCILLATIONS. THE VIBRATIONS STOPPED AFTER ABOUT 10 SECONDS; BUT WERE FOLLOWED BY TWO MORE EPISODES OF SIMILAR STRONG VIBRATIONS. THERE WAS SOME GAIN AND LOSS OF ALT AND SCOTTISH CTL WAS NOTIFIED OF THIS. AFTER THINGS SETTLED DOWN; THE #1 AUTOPLT WAS ENGAGED AND OPS WERE NORMAL TO AMS. THE ONLY SYS MALFUNCTIONS NOTED WERE UPPER YAW INOP LIGHTS ILLUMINATING. SWITCHES WERE RECYCLED AND LIGHTS REMAINED OUT. CAUSE OF VIBRATIONS IS UNKNOWN. NO INJURIES OF ANY KIND WERE RPTED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR IS A DC10-30 CAPT AND HE SAID THAT MAINT WAS UNABLE TO DETERMINE THE CAUSE OF THE VIBRATIONS. THE MAINT PERSONNEL RAN SOME TESTS; HE SAID; AND CONCLUDED THEIR EXERCISE BY PUTTING THE #2 AUTOPLT ON THE MEL. THE CAPT SAID THAT HE HAS CHKED WITH THE MAINT DEPT SEVERAL TIMES. THEY HAVE NOT HAD FURTHER PROBS WITH THE ACFT. THE #2 AUTOPLT WAS REPLACED. THE ALT ONLY VARIED ABOUT 200 FT UP AND DOWN DURING THE VIBRATION EPISODES. HE SAID THAT THE CREW WAS VERY CONCERNED AS NONE OF THEM HAD EVER EXPERIENCED ANYTHING LIKE THIS BEFORE.