AN EMB135 IN DSCNT FROM FL250 TO FL210 DECLARED AN EMER AND DIVERTED DUE TO SMOKE AND ASHY SUBSTANCE COMING INTO THE COCKPIT AND CABIN.

Narrative

I WAS FLYING FROM XYZ TO ZZZ WHEN APPROX 150 MI FROM ZZZ WHILE DSNDING FROM FL250 TO FL210 WE BOTH NOTICED SMOKE ENTERING THE COCKPIT FROM THE FLOOR VENTS; THE SMELL OF SMOKE AND AN ASHY SUBSTANCE COMING INTO THE COCKPIT. AT THE SAME TIME THE FLT ATTENDANT CALLED FROM THE CABIN TO NOTIFY US THAT SMOKE WAS ENTERING THE CABIN. I DECLARED AN EMER AND REQUESTED VECTORS TO THE CLOSEST ARPT FOR LNDG. WE BOTH PERFORMED OUR SMOKE IN THE CABIN AND COCKPIT PROCS AND EMER PROCS. WE WERE VECTORED TO ZZZ WHILE THE FA PREPARED THE CABIN FOR AN EMER LNDG. WE WERE VECTORED TO THE ARPT AND LANDED. AFTER LNDG WE STOPPED ON THE RWY AND ASKED THE CFR TO INSPECT THE ACFT FOR ANY FIRE OR DAMAGE. THEY CLRED THE ACFT AND WE TAXIED TO THE TERMINAL UNDER OUR OWN PWR WHERE THE PAX WERE DEPLANED USING A STAIR/RAMP. THERE WERE NO INJURIES OR DAMAGE TO THE ACFT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED WHILE DSNDING THE SMOKE AND ASH ENTERED THE COCKPIT AND THE CABIN ATTENDANT RPTED THE FORWARD CABIN HAD SMOKE. THE RPTR SAID AN EMER WAS DECLARED AND A DIVERSION STARTED. THE RPTR STATED THE CREW NOTED THE L PACK OVERHEAT WARNING LIGHT WAS ON AND THE PACK WAS INOPERATIVE. THE RPTR SAID THAT ON THE GND MAINT FOUND THE L PACK AIR CYCLE MACHINE HAD COMPLETELY COME APART ALLOWING HIGH PRESSURE ENGINE BLEED AIR TO BLOW OIL AND INSULATION INTO THE AIR CONDITIONING DUCTING. THE RPTR STATED THE SOURCE OF THE 14TH STAGE AIR WAS THE AUTO ICING SYSTEM DETECTING ICE AND SWITCHING FROM 9TH STAGE AIR TO 14TH STAGE HIGH PRESSURE ENGINE BLEED.