As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NOTED EXTERIOR BLEED AIR NOISE COMING FROM LEFT MAIN GEAR DOOR AREA. FOUND CRACK AT FLANGE IN APU BLEED AIR DUCT. REMOVED AND REPLACED APU BLEED AIR DUCT ELBOW FWD OF APU SOV (CTR ISOL VLV), CHECKED FOR AIR LEAKS. NO AIR LEAK NOTED. REF AMM 20-11-00.