As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
COCKPIT ODOR: HAD A MUSTY FAINT SMELL IN THE COCKPIT WITH THE VENT OPEN ON THE LEFT PILOT SIDE. ALSO AFTER ENGINES STOPPED BACK IN THE CABIN SIMILAR SMELL LIKE A MUSTY/ HUMIDITY SMELL. CORRECTIVE ACTION; REPLACED HEPA FILTER REF. CE 700 AMM 21-70-10. NO FURTHER SMELL NOTED.