As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW AND PASSENGERS NOTICED THE SMELL OF EXHAUST AFTER THE APU WAS STARTED ON THE DECENT FOR LANDING. MAINTENANCE WAS CALLED TO TROUBLESHOOT THE CAUSE AFTER LANDING. ON INSPECTION, THEY FOUND THE APU TURBINE HOUSING HAD A CRACK IN IT AT ABOUT THE 5 O'CLOCK POSITION, ADJACENT TO THE FUEL NOZZLE. THE APU WAS PLACED ON MEL AND IS BEING REMOVED AND A LOANER INSTALLED.