FLC DISTR SMOKE IN COCKPIT.

Narrative

WHILE DSNDING THROUGH FL300 WE STARTED TO SMELL BURNING IN THE CABIN. WE IMMEDIATELY TURNED OFF ALL UNNECESSARY ELECTRICAL EQUIP AND SMELL CONTINUED. DSNDING THROUGH APPROX FL240 SMOKE STARTED FILLING THE CABIN. WE DONNED OXYGEN MASKS AND DROPPED MASKS FOR PAX. I TOLD THE CTLR THAT WE HAD SMOKE IN THE CABIN AND NEEDED LOWER. NOT KNOWING WHAT WAS CAUSING THE PROB; I ASKED THE CTLR WHAT WAS THE NEAREST ARPT TO WHICH HE SAID; 'CLEVELAND.' I SAID THAT INITIALLY I WOULD LIKE TO HEAD FOR CLEVELAND. SOMETIME WHILE THIS WAS TAKING PLACE; WE WERE CLRED TO 12000 FT. AT THIS TIME MY PAX CAME FORWARD AND SAID HE THOUGHT THE SMOKE WAS COMING FROM THE CABIN BLOWER. I LOOKED AT THE FAN SWITCH WHICH IS VERY SMALL IN THE LEAR AND IT WAS ON. I IMMEDIATELY TURNED IT OFF. WITHIN A FEW SECONDS THE SMOKE STOPPED. WE WERE AT FL195. FEELING COMFORTABLE THAT THIS WAS THE PROB; I ASKED THE CTLR FOR FL190 AND RECEIVED IT. THE CABIN RETURNED TO NORMAL AND WE ASKED FOR A CLRNC TO DSND NORMALLY INTO DETROIT AND LAND AT OUR MAINT BASE. NO FURTHER PROBS AROSE. I FEEL LIKE WE PREPARED FOR THE WORSE AND TOOK IMMEDIATE ACTIONS. AFTER SOLVING THE PROB; I BELIEVE WE WERE JUSTIFIED IN DSNDING FROM FL190; 75 NM OUT OF DETROIT TO RETURN THE ACFT TO OUR MAINT BASE. SUPPLEMENTAL INFO FROM ACN 313787: SEEING THAT THE CABIN WAS NOW CLR OF SMOKE WE DECIDED TO CONTINUE TO DETROIT WILLOW RUN WHICH IS OUR MAINT BASE. A SAFE CONTINUATION TO OUR DEST WAS RECEIVED IN THE CLRNC FROM ZOB AND WE LANDED AT WILLOW RUN WITH NO FURTHER INCIDENT.