FLC OF AN SF340 ON INITIAL CLB ENCOUNTERS SEVERE WAKE TURB FROM A B737. BRIEF LOSS OF ACFT CTL.

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IT HAS BEEN MY EXPERIENCE THAT TKOFS BEHIND B737'S MAY RESULT IN WAKE TURB. IN ANTICIPATION; I POINTED THIS OUT TO THE FO AND HAD HIM SET MAX TKOF PWR. THE B737 DEPARTED ON A 255 DEG HDG AND WE WERE ASSIGNED A 210 DEG HDG. OBSERVING THE EXHAUST SMOKE AND THE RELATIVE (1000 FT ABOVE) ALT AND THE SEPARATION; WHICH I ESTIMATED TO BE 3 NM; I BEGAN A 10 DEG BANK L TURN TO 210 DEGS. UPON ENCOUNTERING THE WAKE TURB UPSET; THE ACFT ROLLED L. COUNTERING WITH FULL R AILERON TO THE STOPS; THE ACFT ROLLED AN ADDITIONAL 10 DEGS L. AFTER NEUTRALIZING THE CTLS; THE ACFT ROLLED R; COUNTERING WITH FULL L AILERON TO THE STOPS; THE ACFT ROLLED AN ADDITIONAL 10 DEGS R. STOP TO STOP! NEVER BEFORE! B727'S AND DC9'S (INCLUDING DERIVATIVES) AIRBUS 320'S NEVER CAUSE THIS PROB. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT THE ROLL ACTION WAS VERY AGGRESSIVE AND LASTED FOR ABOUT 4 SECONDS IN EACH DIRECTION WITH A 3-6 SECOND PAUSE BTWN DIRECTIONS. HE STATES THAT HE HAS NEVER HAD THIS KIND OF WAKE REACTION BEHIND ANY OTHER SIMILAR SIZE ACFT. HE ALWAYS TRIES TO PREPARE FOR SUCH A SIT BUT THIS STILL WAS EXTREME. THE FACT THAT THERE WAS A VIRTUAL NO WIND CONDITION WAS A MAJOR CONTRIBUTOR. IN TALKING WITH THE TRAINING OFFICER IT WAS RECOMMENDED THAT THE YAW DAMPER SHOULD NOT BE ENGAGED SO SOON. THE YAW DAMPER IS RATHER SLOW RESPONDING AND THE FEET DO A BETTER JOB OF CTLING THE YAW ACTION; WHICH WOULD HAVE HELPED IN THIS INCIDENT. RPTR BELIEVES THAT ATC NEEDS TO RECOGNIZE THE B737 CAN CAUSE SUCH WAKE AND ALLOW GREATER SEPARATION ON DEPS.