As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DIVERTED FOR LOUD VIBRATION AND NOISE, APPEARS TO BE FROM NR 1 A/C PACK. A BURNING ODOR WAS EVIDENT. VIBRATION AND NOISE GREW LOUDER WITH INCREASED AIRSPEED. MX FOUND BOLT ON UPPER HEAT EXCHANGER MOUNT MISSING WASHER AND NUT INSTALLED IAW AMM 20-10-01. NO VIBRATION NOTED OR BURNING ODOR NOTED. ACFT APPROVED FOR RETURN TO SERVICE.