What was found
EXCESSIVE NOISE IN FLT DECK AND AT ROWS 10-12. AIRFLOW AND NOISE VERYLOUD IN CABIN ROWS 10-12. MT 21-22-00 FOUND 4-5 DECIBLE DROP WITH RT RECIRC FAN BEING TURNED OFF. FOUND ROW 12 SEATS 12A&F TO BE LOUDER THAN NORMAL FROM SIDEWALL RISERS AND OVERHEAD AREA LOUDER THAN REMAINING AC. CLEANED OVERHEAD DUCT. ACCOMPLISHED COMPLETE DUCT CLEAN OF AIRCRAFT REF MT21-22-00. ALSO FOUND DIFFUSER IN COCKPIT ON OVERHEAD PANEL INSTALLED BACKWARDS. REINSTALLED DIFFUSER, COCKPIT CHECKS WITHIN LIMITS.