As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING OUT OF DEPARTURE, CREW HEARD POPPING NOISE AND SMELLED A CHEMICAL ODOR. ACFT DIVERTED BACK TO DEPARTURE. ACFT LANDING WAS UNEVENTFUL. MAINTENANCE FOUND THE COCKPIT PORTABLE FIRE EXTINGUISHER DISCHARGED. THE CABIN PORTABLE FIRE EXTINGUISHER WAS PLACED IN COCKPIT, THE DISCHARGED FIRE EXTINGUISHER WAS REMOVED FROM THE ACFT AND SENT TO MFG FOR EVALUATION/INVESTIGATION. THE CABIN PORTABLE FIRE EXTINGUISHER WAS DEFERRED IAW MEL.