As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON RUN UP AT IDLE, THE CREW SMELLED A BURNING ODOR, NEAR RT AFT SEAT & COPILOT SEAT. INVESTIGATED & COULD NOT DUPLICATE ANY ODOR. LOOKED FOR SIGNS OF ELEC COMPONENTS THAT HAVE OVERHEATED. NO DISCREPANCIES NOTED. GND RAN ACFT & TEST FLEW WITH NO ADDITIONAL ODOR. RETURNED ACFT TO SERVICE. ATA CODE 2140 USED AS A REFERENCE EVEN THOUGH THE SOURCE OF THIS SMELL COULD NOT BE FOUND.