What was found
DURING FLIGHT PREPARATION, WITH APU ONLY RUNNING, GOT A "BLEED 2 LEAK" CAS MESSAGE. RESET SYSTEM, MESSAGE WENT AWAY MOMENTARILY, THEN CAME BACK IN ABOUT 5 MINUTES. LARGE AMOUNT OF AIR NOISE HEARD IN REAR BAGGAGE COMPARTMENT, WHICH STOPPED AT THE SAME TIME THE "BLEED 2 LEAK" MESSAGE RETURNED. DISCOVERED ENGINE / APU TUBE ASSY DUCT (P/N 550-18516-407) CRACKED. POSSIBLE HIDDEN FAILURE.