AN ATX C550 FLC HIT THE WAKE OF AN ACR B737 AND ROLLED 90 DEGS TO THE R TWICE. THE ROLLS WERE ALSO ACCOMPANIED BY UP TO 10 DEGS OF YAW. THE CAPT APPLIED ALL OF THE AVAILABLE AILERON AND RUDDER AUTH TO COUNTER THE WAKE EFFECT. NO PRIOR WARNING WAS GIVEN TO THE FLC ABOUT THE PRECEDING TFC HOWEVER; LATER THEY WERE ASSURED BY THE TWR THAT THE REQUIRED SEPARATION CRITERIA HAD BEEN MET.

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AFTER GOING MISSED APCH FROM W54 (LEBANON; TN) DUE TO WX; WE WERE CLRED VIA RADAR VECTORS FOR THE ILS APCH INTO BNA AT 3000 FT WITH 180 KT SPD RESTR. APPROX 15 MI OUT ON THE LOC; ACFT CONFIGN WAS CLEAN AT 180 KTS WHEN THE ACFT ROLLED R APPROX 90 DEGS. THE CAPT; WHO WAS FLYING; APPLIED FULL L AILERON AND RUDDER. THESE ACTIONS WERE ENOUGH TO STOP THE ROLLING ACTION WHICH LASTED APPROX 15- 20 SECONDS. THE REASON FOR THE WAKE TURB WAS BECAUSE WE WERE 4 MI IN TRAIL OF A B737. THE WINDS AT THE SURFACE AND AT ALT WERE CALM; THEREFORE SETTING UP A BAD SIT DUE TO WAKE TURB. THROUGHOUT THE WHOLE ORDEAL WE WERE NEVER INFORMED BY ATC THAT WE WERE FOLLOWING ANYONE. I FAULT ATC DUE TO THE LACK OF COM. HAD WE KNOWN THAT WE WERE FOLLOWING A LARGE ACFT WE WOULD HAVE COME IN ABOVE HIS FLT PATH THEREFORE AVOIDING THIS WHOLE SIT. ON THE GND WE EXPLAINED WHAT HAD HAPPENED TO THE PAX AND CALLED TWR TO CONFIRM THAT THE SPACING WAS PROPER. THE TWR SAID THAT THEY WOULD BE MORE AWARE IN FUTURE SITS AND BE SURE TO INFORM SMALLER ACFT OF THEIR DISTANCE IN RELATION TO LARGER ACFT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR WAS FO ON A CESSNA CITATION II MAKING AN APCH TO RWY 20R AT BNA WITH 8 PAX ON BOARD WHEN THEY HIT THE WAKE OF A B737-300. HE SAID THAT HE AND THE CAPT HAD TALKED ABOUT THE CALM WINDS CREATING PERFECT WAKE TURB CONDITIONS AND THEY BOTH LOOKED FOR TFC AHEAD; BUT DID NOT SEE ANY ACFT. BOTH PLTS HAD BEEN THROUGH THE FLT SAFETY TRAINING SCHOOL WHICH HAD INCLUDED WAKE TURB AND UNUSUAL ATTITUDE RECOVERY TECHNIQUES ACCORDING TO THE RPTR. LATER; THEY DISCOVERED THAT THE B737; IN FRONT OF THEM; HAD INTERCEPTED THE GS AT 3800 FT WHILE THEY HAD BEEN ASSIGNED A 3000 FT INTERCEPT. THIS ALT DIFFERENTIAL WAS FELT TO BE CRITICAL BY THE RPTR; AND HE SAID THAT THIS AND THE CALM WINDS PRACTICALLY GUARANTEED THAT THEY WOULD HIT THE B737'S WAKE. THE FO SAID THAT HE INITIALLY GRABBED THE CTL WHEEL ALTHOUGH THE CAPT WAS ALREADY HAND-FLYING THE ACFT. HE SAID THAT THE ROLL AND YAW WERE VERY VIOLENT AND RAPID AND HE WAS STARTLED; BUT HE LET GO OF THE CTL WHEEL SO THAT HE WOULD NOT INTERFERE WITH THE CAPT'S EFFORTS TO RECOVER. THE CAPT APPARENTLY KEPT THE FO IN THE LOOP BY TELLING HIM WHAT HE WAS DOING AS HE ADDED AILERON AND RUDDER. HE HAD TO USE FULL TRAVEL ON BOTH TO ROLL THE ACFT LEVEL; BUT AS HE WAS BRINGING THE CTLS BACK TO NEUTRAL THEY HIT THE WAKE AGAIN AND AGAIN THE ACFT ROLLED RAPIDLY TO THE R TO A 90 DEG BANK ANGLE. THE ACFT AGAIN RESPONDED SLOWLY TO FULL RUDDER AND AILERON INPUT AND FINALLY RETURNED TO A WINGS LEVEL POS. ACCORDING TO THE FO; THE CAPT SAID THAT HE WAS PREPARED TO CONTINUE THE ROLL IF THE BANK ANGLE HAD PASSED 90 DEGS AS THEY HAD BEEN TRAINED. AFTER THEY RECOVERED A SECOND TIME; THE FO SAID THAT HE RPTED THE ROLLS TO THE CTLR AND THAT IS WHEN THE CTLR TOLD THEM OF THE B737 AHEAD OF THEM. AFTER THEY LANDED THEY FOUND OUT MORE ABOUT THE SIT DURING A CONVERSATION WITH TWR PERSONNEL. THEY WERE TOLD OF THE DIFFERENT GS INTERCEPT ALTS AND WERE ALSO ASSURED THAT THE IN-TRAIL DISTANCE WAS NEVER LESS THAN 4 MI. THE TRACON CTLR RELAYED HIS APOLOGY ABOUT NOT TELLING THEM ABOUT THE B737 BEFOREHAND; AND ALSO MENTIONED THAT THEY WERE NEVER CLOSER THAN 4 MI. ONE OF THE PAX ON BOARD; A FORMER FIGHTER PLT; SAID THAT HE THOUGHT THAT IT WAS 'ALL OVER' ON THE SECOND ROLL ACCORDING TO THE RPTR.