AN SMA PLT SUFFERS VERTIGO DURING APCH TO BED; MA.

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FLT FROM DCA TO BED. FIRST PART CONDUCTED VFR (ORIGINALLY FILED IFR BUT ELECTED TO DEPART VFR). 2 CTLRS ASKED WHY I WAS FLYING THROUGH 5000 FT AND THEN 7000 FT. I EXPLAINED I HAD BEEN CLRED TO 5500 FT AND THEN 7500 FT BY PREVIOUS CTLRS. IFR PLAN IN THE SYS CONFUSED CTLRS. PICKED UP IFR CLRNC OVER CMK; FLEW ON TOP AT 8000 FT TILL 5000 FT AT DREEM. BED ATIS WAS 2500 FT SCATTERED SO SET THE PLANE UP FOR VISUAL APCH LNDG LIGHT ON; STROBES; ETC. WX CHANGED ABRUPTLY WITH SPECIAL ATIS PICKED UP 10 MI OUT. REQUIRED ILS AT BED APCH DIDN'T TURN OFF LNDG LIGHT AND STROBES. THEY CAUSED EXTREME VERTIGO; SPATIAL DISORIENTATION ON ENTERING CLOUDS. I HAD TO FIGHT TO KEEP AIRPLANE STRAIGHT AND LEVEL. IN THE COURSE OF RECOVERING FROM DISORIENTATION; I EXPERIENCED 30-40 DEGS TURN OFF COURSE AND DSCNT TO 1500 FT (FROM 2000 FT ASSIGNED). I ADVANCED THROTTLE FOR MISSED APCH WHEN CTLR CALLED TO GIVE VECTORS FOR ANOTHER APCH. DURING VERTIGO; I BECAME CONVINCED I HAD A GYRO FAILURE OF EITHER ATTITUDE INDICATOR OR TURN COORDINATOR. FOCUSED ON ALTIMETER; DIRECTIONAL GYRO TO RECOVER. CTLR GAVE ME A 360 DEG VECTOR FOLLOWED BY A 180 DEG VECTOR FOLLOWED BY A 140 DEG VECTOR TO INTERCEPT. HOWEVER; I NEVER INTERCEPTED THE ILS ON THAT HDG. I ENDED UP BREAKING OUT N OF THE ARPT AT 2000 FT ABOUT MIDFIELD AND THEN CIRCLED TO LAND. I THINK THAT I MAY HAVE BEEN IN A TURN GREATER THAN 45 DEGS -- PERHAPS 60 DEGS DURING VERTIGO AND EITHER TURN COORDINATOR OR ATTITUDE MAY HAVE LAGGED IN RECOVERY. PERHAPS ALSO THE DIRECTIONAL GYRO MAY HAVE PRECESSED. ISSUES: ASSUMING VISUAL APCH FOR AN HR THEN ILS WITHIN LAST 5 MINS. DIDN'T GET STROBES/LNDG LIGHT OFF. I SHOULD HAVE ASKED FOR MORE THAN A QUICK VECTOR BACK TO ILS TO SET UP STABILIZED APCH.