What was found
LOUD AIR NOISE COMING FROM MAIN DOOR DURING FLT. PRESSURIZED ACFT & DUPLICATED LOUD AIR NOISE. FOUND PASSENGER DOORS TOP STEPS BONDING WIRE CAUGHT BETWEEN DOOR & AIRFRAME. DISCOVERED CAUSE OF BONDING WIRE BEING LOOSE TO BE THAT PAX DOORS TOP STEPS MOUNTING BASE CRACKED & NOT HOLDING BONDING WIRE IN PLACE. PRESSURIZED ACFT AGAIN, ENSURING BONDING WIRE WAS NOT CAUGHT BETWEEN AIRFRAME & DOOR. NO LEAK, NOISE, OR DAMAGE TO BONDING WIRE. REMOVED PASSENGER DOORS TOP STEP CRACKED MOUNTING BASE & INSTALLED NEW BASE. TIED BONDING WIRE IN CORRECT POSITION & VERIFIED WIRE NO LONGER GETS CAUGHT. ALL WORK PERFORMED IAW AMM 21-31-BO & SPM 51-21-45.