As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH RIGHT RECIRCULATION FAN ON, F/A COMPLAINED CABIN VERY NOISY, DIFFICULT TO HEAR PA. ALSO VERY NOISY IN COCKPIT WITH PACKS ON AND RIGHT RECIRCULATION FAN OFF. FOUND RT RECIRCULATION FAN FILTER COLLAPSED FROM DIRT & PLEATED MATERIAL DISINTEGRATING. REMOVED AND REPLACED FILTER. SYS OPS CHECKED GOOD.