As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STRONG BURNING SMELL IN CABIN WHEN APU STARTED ON THE GROUND. SMELL WENT AWAY WHEN TURNED OFF.<[01] ACCOMPLISHED CONDITIONAL INSPECTION FOR SMOKE OR FUMES IN CABIN SOURCE UNKNOWN IAW FIM TASK 21-00-00-810-830.<BR>NO FUMES OR SMELL NOTED