As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RT RECIRC FAN TOO LOUD. PLZ WORK WITH CH1637. ACP COCKPIT GROUND NOISE LEVEL CHECK IAW AMM. VERIFIED BOTH PACKS IN LOW FLOW WITH MCDU. RT RECIRC FAN ON: 108DB. RT RECIRC FAN OFF: 107DB. NOTE - THIS IS ONE OF THE QUIETER 757(S) IN UA FLEET ON GROUND. CLEANED DUCTS REF MM. DECIBELS ARE 73 WITH RIGHT RECIRC ON AND 72 OFF VELOCITY IS 3150 AND FLOW RATE IS 345.