As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HALF WAY DURING DESCENT NOTICED MUSTY SMELL IN COCKPIT. DESCRIPTION OF ODOR/FUMES: PERSISTENT, DIRTY SOCKS AND MUSTY DRY SMELL. APPARENT CABIN SOURCE: PACK #1. FLIGHT DECK. NO VISIBLE SMOKE/HAZE. NO MEDICAL ATTNETION REQUIRED.-PER TSM 05-50-00-810-831-A. PERFORMED ENG RUN WITH CREW ASSISTANCE, FOUND PACK #1 AT SOURCE. SEE LP 3455273-2 FOR CORRECTIVE ACTION. MOC # 110495.