As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: SMELLED AN ODOR ON GROUND IN MKE. DID NOT THINK IT WAS A TOXIC FUME. SMELL PERSISTED THROUGH OUT FLIGHT. ON ARRIVAL SMELL BECAME EXTREMELY PUNGENT. CREW MEMBERS WITH METALLIC TASTE IN MOUTH AND BURNING THROATS/EYES. SOURCE OF ODOR DETERMINED TO BE THE APU. REPLACED APU AND ACCOMPLISHED A SATISFACTORY LEAK / OPERATIONAL CHECK PER TASK CARD 26L00021004. (CLOSED)