As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 6009 - PHX-DSM - DURING PRE-FLIGHT, THE APU SHUT DOWN, WHEN THE APU SHUT DOWN SMOKE FROM THE EXHAUST CAME INTO THE AIRCRAFT ALERTING THE CREW TO THE SMELL OF SMOKE. THE CREW FEARED A FIRE SO THE DECLARED A GROUND EMERGENCY. THE FIRE TRUCKS RESPONDED AND NO FIRE WAS FOUND. THE AIRCRAFT WAS RETURNED TO SERVICE. (M)