AN ACR E120 FLC HIT THE WAKE OF A B767 WHILE ON DOWNWIND. THE APCH CTLR DID NOT GIVE THE FLC PRIOR NOTICE OF WHAT ACFT THEY WERE FOLLOWING AND; THE RPTR ALLEGES; WOULD NOT TELL HIM THE TYPE AFTER THE ENCOUNTER.

Narrative

WHILE ON L DOWNWIND FOR RWY 27L AT ATL AND DSNDING THROUGH 7000 FT; EXPERIENCED SEVERE WAKE TURB. WE WERE 5 MI IN TRAIL OF A B767-300 BEING VECTORED FOR AN APCH. NO WARNINGS WERE GIVEN ABOUT THE ACFT AHEAD. EXPERIENCED 2 UNCOMMANDED ROLLS; ONE IN EACH DIRECTION; OF BTWN 20 DEGS AND 30 DEGS. TOTAL DURATION OF INCIDENT WAS APPROX 15 SECONDS. THIS SORT OF OCCURRENCE IS COMMON IN AND OUT OF ATL. CTLRS THERE ARE CONSTANTLY PUTTING US INTO THE PATH OF HEAVIER EQUIP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR WAS THE FLYING FO ON AN EMB120 THAT WAS DSNDING THROUGH CLOUDS AT 7000 FT WHEN THE ACFT HAD A VIOLENT WAKE ENCOUNTER. THE FO SAID THAT THE CREW SAW AN ACFT ON THEIR TCASII DISPLAY THAT SHOWED 3 MI AHEAD AND DSNDING BELOW THEM. THE APCH CTLR HAD NOT MENTIONED THE TFC TO THEM AND THEY ASSUMED THAT THE DISPLAY WAS SHOWING ANOTHER COMMUTER ACFT. AS THEY FELT THE INITIAL NIBBLES OF THE WAKE; THE FO SAID THAT HE GRIPPED THE CTL TIGHTLY AND PREPARED TO DISCONNECT THE AUTOPLT. THE ACFT SUDDENLY ROLLED TO THE R REACHING 30 DEGS OF BANK EVEN THOUGH THE FO PUT IN FULL L RUDDER AND AILERON. THE ACFT STOPPED THE ROLL AT THAT POINT; HESITATED THEN SLOWLY ROLLED TO A WINGS LEVEL ATTITUDE. HE RELAXED THE CTL INPUTS; HE SAID; BUT A FEW SECONDS LATER THE ACFT ROLLED JUST AS VIOLENTLY TO THE L AGAIN WITH FULL RUDDER AND AILERON TO COUNTER. THIS TIME THE ROLL SEEMED TO STOP AT 20 DEGS THEN VERY SLOWLY INCREASE TOWARD 30 DEGS; BUT DID NOT QUITE MAKE IT THAT FAR. THE ACFT AGAIN HESITATED AT THE MAX BANK ANGLE AND THEN SLOWLY RECOVERED. AFTER THIS IT WAS AGAIN SMOOTH. THE FLC RPTED THE ENCOUNTER TO THE APCH CTLR AND ASKED WHAT KIND OF ACFT IT WAS. THE CTLR; ALLEGEDLY; WOULD ONLY RESPOND THAT THE ACFT WAS 5 MI AHEAD OF THEM AND THEY HAD LEGAL SEPARATION. THE CTLR LATER ASSIGNED THEM A PARALLEL RWY INSTEAD OF REQUIRING THEM TO FOLLOW THE; AS YET UNKNOWN; TFC. AS THE CREW BROKE OUT OF THE CLOUDS ON FINAL APCH THEY COULD SEE THAT THE OTHER ACFT WAS A B767-300. IT WAS NEW AND HAD A LARGE IDENT LOGO ON THE ACFT. THE RPTR SAID THAT HE HAS HAD UNUSUAL ATTITUDE RECOVERY TRAINING AT HIS AIRLINE AND HE FEELS THAT IT WAS VERY HELPFUL DURING THIS ENCOUNTER.