What was found
WE BOTH HEARD A LOUD POP/BURST FOLLOWED BY THE CONTINUAL SOUND OF FAST LEAKING AIR. IT SOUNDED LIKE A DOOR SEAL OR AIR DUCT PIPE BURST. WE THEN GOT MULTIPLE RED AND YELLOW CASS MESSAGES ON THE SCREEN. I TURNED AROUND AND IMMEDIATELY NOTICED THAT SMOKE WAS FILLING THE BACK OF THE CABIN BY THE MAIN ENTRY DOOR. IT APPEARED TO BE HOT BLEED AIR SMOKE. REMOVED AND DISASSEMBLED ACM AND REASSEMBLED WITH A NEW TURBINE. DETERMINED TE BE NORMAL OPERATION WHEN BLEED AIR OVERHEAT TURNS ON EMER PRESS.